Category: Health

From the 1970’s until very recently, we were told that all fats were bad, and we should eat as little fat as possible. We now know that polyunsaturated omega-3 fatty acids are not only good for us, they are essential. What is the difference between saturated and unsaturated fats? Are some fats “good” and other fats “bad”?

What is fat?

Fats and oils are large molecules made of carbon, hydrogen, and a little bit of oxygen. Each fat molecule contains 3 fatty acid tails attached to a glycerol backbone. The result is called a “triglyceride.” Every fat molecule (or triglyceride) has the same glycerol backbone; it’s the different types of fatty acids attached to that backbone that give different kinds of fats their unique properties. Each fatty acid is essentially a long chain of carbon atoms with lots of hydrogen atoms attached to it along both sides, and an “acid” group on one end.

Fat is good.

We think of fat as bad; as something we want to get rid of. We think that the less we have of it the healthier we are. When we have too much of it, we feel ugly and unhappy. But the truth is that fat is incredibly important. Fat is vital to human life and health.

Fat is our portable battery pack.

Fat is an efficient, lightweight, flexible, and portable source of energy. All animals store energy as fat for these reasons. If we were meant to burn carbohydrates for energy, we would have the ability to sprout big lumps of starch all over our bodies, the way plants do. But Mother Nature is smart. She knows that animals need to move around in the world and can’t afford to be weighed down by heavy potato-like structures. Our bodies can only store hours’ worth of energy as starch (glycogen), but we can store months’ worth of energy as fat.

Fat contains more than twice the amount of energy per pound than carbohydrates do. You probably already know this but may not have thought about it this way: carbohydrate contains 4 calories per gram and fat contains 9 calories per gram. Calories are units of energy. Fat can pack a lot more energy than starch can.

Saturated fat is the preferred fuel of the heart, which is why the heart has some saturated fat wrapped around it.

Our brains are mostly made of fat.

Approximately 60% of the brain is made out of fat. In addition to being an important component of every brain cell membrane, fat also is a major component of myelin, the special insulating material that is wrapped around the electrical wiring pathways of our brain (damage to myelin is the hallmark of Multiple Sclerosis). Myelin is approximately 50% fat and 50% cholesterol.

Fat protects us.

Fat cushions our delicate vital organs so they won’t be bruised or damaged when we run, jump, or fall. Fat is a critical component of our skin—the barrier between us and the outside world—preventing us from randomly absorbing everything we come into contact with. Fats are integral parts of the outer lining (membrane) of every cell in our bodies, forming a water-tight seal that keeps stuff that should be inside the cell inside and stuff that should stay outside of the cell outside. What’s more, inside each cell are mini-compartments, like the nucleus and the mitochondria, that need to keep their contents separate from the inside of the rest of the cell, so they each have fatty membranes, as well.

Fats lubricate our moving parts.

Fats are important ingredients in tears, joint fluids, and other slippery substances that we need to function properly.

Dietary fat is required for vitamin absorption.

Certain essential vitamins, such as A, D, E and K, all require fat in order to be absorbed by our intestines. Fat itself is so important to our health and survival, that we are designed to absorb about 99% of all the fat we eat. This is not true of many plant substances that we think of as so important to our health, such as vegetable iron and beta-carotene.

How much fat do we need to eat?

This is a difficult question. Fat is so important to every cell in our bodies that we can make fat out of anything—we can make it out of dietary proteins from animals and plants, and we can make it out of carbohydrates, like sugar and starch. That doesn’t mean that these are the ideal ways to obtain fats—for all we know, the body would prefer to get its fat directly from the diet so that it doesn’t have to go through the hassle of turning other dietary ingredients into fat—it just means that it’s possible. There are only a few fats (essential fatty acids) that we absolutely must eat because we can’t make them ourselves (see below).

What is the difference between saturated and unsaturated fat?

A saturated fatty acid has the most hydrogen atoms it can possibly carry—it is therefore “saturated” with hydrogen. Every carbon atom is attached to as many hydrogen atoms as it can hold. Each carbon-hydrogen bond carries energy, so the more hydrogen atoms that are bound to a fat, the more energy you can get out of that fat when you burn it. Saturated fat has more energy, and therefore more calories, per pound.

Unsaturated fats have less hydrogen—at least one of the carbons will have a hydrogen missing. Since there is no hydrogen for that carbon to bind to, the carbon atom forms a double bond to a neighboring carbon atom instead. If a fat has one double bond, it is called “monounsaturated” (missing one hydrogen). Oleic acid, the primary fatty acid in olive oil, is a well-known example of a monounsaturated fatty acid, or MUFA. If it has more than one double bond, it is called “polyunsaturated” (missing more than one hydrogen). Omega-3 and omega-6 fatty acids (see below) are well-known examples of polyunsaturated fatty acids, or PUFAs.

Most fats occurring in nature contain mixtures of saturated, monounsaturated, and polyunsaturated fatty acids. Olive oil contains approximately 17% saturated fatty acids, 71% MUFA (oleic acid), and 11% PUFAs. Coconut oil contains more than 90% saturated fat. Beef fat contains nearly equal parts saturated fat and monounsaturated fat (most of which is oleic acid, the primary fatty acid in olive oil) and approximately 5% polyunsaturated fat, depending on what the animal is fed.

Saturated fats, with their full load of energy-packed hydrogen bonds, are straight molecules that stack together efficiently, and are therefore solid at room temperature (like lard, cocoa butter and coconut oil). Unsaturated fats, with their weaker double bonds, are crooked, because double bonds create kinks in the backbone. They do not pack together efficiently and are therefore liquid at room temperature (like olive oil). Imagine a box full of straight straws—they pack easily and you can fit a lot of straws into the box. However you can’t fit as many bendy straws into that same box because they take up more space. They also move around more inside the box.

When molecules have room to move around easily, they are more likely to form liquids than solids. Saturated fats are very stable, whereas unsaturated fats (oils) are fragile. The carbon double bonds in unsaturated fats are weak and vulnerable to chemical attack compared to the strong carbon-hydrogen bonds in saturated fats. This is why unsaturated fats (oils) go rancid (become oxidized) when exposed to air, whereas you can leave lard or butter on the countertop for a long time without worrying about it. Ghee, which is butter with all of its proteins removed (pure butterfat), can be stored at room temperature indefinitely.

Are saturated fats unhealthy?

Our bodies need both types of fats—saturated and unsaturated. Saturated fats are good for things like insulation (myelin), cushioning (abdominal fat around our organs), and storage (body fat under the skin) purposes. Unsaturated fats are good for flexibility and fluidity purposes, such as in membranes and body fluids. It doesn’t make sense to think of one kind as inherently healthy and the other kind as inherently unhealthy.

Saturated fats are chemically rather boring—they are quite stable (especially as compared to the reactive PUFAs) and it is hard from a common sense point of view to imagine them causing the kinds of trouble they are accused of causing—such as burrowing into heart vessel walls and causing inflammatory plaques that rupture into heart attacks. These are by nature long, smooth, non-irritating substances.

You would not want all of your body fat to be unsaturated. All of your fat would be liquid instead of firm and compact. Not only would you sag everywhere, and begin to resemble a Shar Pei, but your body would have to be bigger, because liquid fats take up more space (like the bent straws in the box).

The misguided belief that saturated fats cause heart disease is rooted in a famous study published in 1970 called “The Seven Countries Study,” in which renowned scientist Ancel Keys claimed that people in countries where more animal fat was eaten had more heart disease then people in countries where less animal fat was eaten. Not only was this study an epidemiological study, and therefore incapable of proving a causal link between any dietary factor and any disease, but there have been numerous studies showing no connection at all between saturated fat and heart disease, including a study of 22 countries published by Yerushalmy and Hilleboe in 1957 (see references below).

The hypothesis that saturated fat causes heart disease now stands on very shaky ground; it is now controversial at best, if not obsolete. Researchers are finding much stronger evidence linking cholesterol dysregulation and heart disease to refined carbohydrates than to saturated fats [Halton 2006, Howard 2006, Mente 2009, Astrup 2010, and Jakobsen 2010].

What are omega-3 fatty acids?

Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs). This means they each have more than one carbon double bond in place of a hydrogen atom. Omega-3 just means that the first double bond in the fat chain is at carbon #3 in the backbone. They are liquid fats (oils).

Even if you eat a 100% fat-free diet, your body will find a way to make almost all of the important fats it needs out of the protein and carbohydrate you eat, but it cannot make omega-3 fatty acids. There are three omega-3 fatty acids that are often called “essential” to our health: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). Because we can’t make them from scratch, we have to eat them.

What is ALA?

ALA is the mother of all omega-3 fatty acids. It is an 18-carbon fatty acid that we can build upon to make EPA (20 carbons), which can in turn be converted to DHA (22 carbons). This process happens in the liver. The problem is that our bodies are not very good at adding carbons to ALA, so we convert only a very small percentage (less than 5%) of the ALA we eat into EPA, and far less of that EPA into DHA. So, the vast majority of the ALA we eat does not turn into precious EPA and DHA; it simply gets burned for energy or stored as fat.

It appears as if ALA itself isn’t required by the body as an important component of any particular cell or molecule; it may only be important as a building block for EPA and DHA. Therefore, if you get enough EPA and DHA in your diet, you may not need any ALA.

What are EPA and DHA?

EPA and DHA, on the other hand, serve important roles in the body. I mention them together because they are almost always found together in nature, and because researchers almost always study them in combination, not individually. Therefore, it can be confusing to try to figure out which one of these compounds is responsible for which benefits. Both EPA and DHA serve as building blocks for anti-inflammatory, pro-healing compounds called “resolvins” and “protectins”, which help to prevent chronic inflammation. They also stabilize the electrical activity of cardiac cell membranes, reducing risk of arrhythmias.

It seems as if DHA may be the most essential of the essential omega-3 fatty acids. The brain and retina require large amounts of DHA for their cells to function properly. It is found in the cell membranes of the brain and retina, helping to keep those membranes fluid and flexible. This is important, because membranes don’t simply act as water-tight walls. They have to be able to wrap around and envelop important nutrients to take them in, or fold outward to let them out. Membranes are very dynamic structures. [I wrote an entire post about the critical role of DHA in the brain and how to include it in your diet in my Psychology Today post: “The Brain Needs Animal Fat.”]

What are good dietary sources of ALA?

ALA is easy to obtain because it is found in such a wide variety of plant and animal foods. Interestingly, Americans obtain more of their daily ALA from animal foods than from plant foods. Oils of seeds, grains, nuts, and legumes contain ALA, with the highest concentrations being found in flaxseed oil, walnuts, canola oil and chia seeds. These foods are therefore marketed as being “rich in omega-3s.” There is also a significant amount of ALA in purslane, an edible succulent green vegetable, and small amounts of ALA in spinach leaves.

The problem is that these sources only contain one of the three essential omega-3 fatty acids; they do not contain any DHA or EPA. And the body can only convert a very small percentage of ALA into EPA (3-8%) and has an even harder time converting ALA into DHA (0-4%), although there are some studies that suggest that, in the complete absence of dietary DHA (such as may occur for vegans), the body may be able to ramp up its ability to convert ALA into DHA to some extent.

What are good dietary sources of EPA and DHA?

EPA and DHA are synthesized primarily by algae and grasses—things that people don’t eat and don’t digest well:

• Marine microalgae
• Seaweed
• Grasses

However, many land animals eat grasses (or should) and many fish (especially small fish) eat algae. Animals eating these green foods accumulate EPA and DHA in their tissues, especially in their fats, livers, and brains. Therefore, good sources of EPA and DHA include:

• Meat from grass-fed animals
• Liver from grass-fed animals (much higher amounts than muscle meats)
• Pasture-raised poultry meat
• Liver from pasture-raised poultry (much higher amounts than bird meat)
• Animal brain
• Small oily fish (anchovy, herring, sardines and mackerel)
• Large oily fish that eat small oily fish (bluefish, tuna, salmon, halibut, bass, and trout)—even farmed fish often contain omega-3’s because of what they are fed.
• Fish liver oils, such as cod liver oil.
• Oysters

Eggs from pastured poultry contain some DHA but are a poor source of EPA.

Full-fat dairy products, especially from grass-fed animals, contain some EPA but are a poor source of DHA.

What are omega-6 fatty acids?

Omega-6 fatty acids are liquid polyunsaturated fatty acids (PUFAs) just like omega-3s are, but they have their first double bond at carbon #6 instead of carbon #3. Whereas there are three important omega-3 fatty acids for human health, there is only one essential omega-6 fatty acid: linoleic acid (LA).

What is linoleic acid (LA)?

It is so unfortunate that linoleic acid, the mother of all omega-6 fatty acids, and alpha-linolenic acid, the mother of all omega-3 fatty acids, have such similar names, because many people confuse the two, but so be it. LA is an 18-carbon polyunsaturated omega-6 fatty acid that we can build upon to make other important molecules, most notably, a 20-carbon omega-6 fatty acid called arachidonic acid.

Linoleic acid is present in all of our cell membranes so that it will be available to form arachidonic acid whenever called upon to do so. Arachidonic acid is required for the process of inflammation to begin. You might be thinking that inflammation is a bad thing, but without it, we cannot mount an immune response to things like bacterial infections and physical injuries. Inflammation is our first line of defense and requires specialized molecules that are made from arachidonic acid: prostaglandins, leukotrienes, and thromboxanes.

While you may not have heard of any of those inflammatory chemicals, you have probably heard of the medicines that are marketed to reduce their activity. NSAIDs such as ibuprofen reduce prostaglandin synthesis. Aspirin reduces prostaglandin synthesis and thromboxane activity. Singulair® is an asthma medication that reduces leukotriene activity.

What are good dietary sources of Linoleic Acid?

Our Western diet is loaded with LA, so not to worry. In fact, we get far more LA than we need. Linoleic acid is present in all kinds of plant and animal foods, but it is present in especially high amounts in vegetable oils (nut and seed oils). Animal fats contain approximately 10-20 % LA, whereas seed oils contain between 50-80% LA. We have been told for decades to avoid animal fats and to choose plant oils instead, and the result is that most of us now get far too much LA in our diet.

The omega ratio problem: are you off-balance?

So, the omega-3 fatty acids are used to create chemicals that have anti-inflammatory properties (resolvins, protectins) and the omega-6 fatty acid LA is used primarily to create chemicals that have pro-inflammatory properties (prostaglandins, leukotrienes, and thromboxanes).

All creatures need a proper balance of these two forces in order to defend themselves (pro-inflammatory elements) and heal (anti-inflammatory elements). Mother Nature understood this, which is why we are gifted with both pathways. In fact, these pathways are intricately connected to each other to keep one another in check. It’s a brilliant system. The pathway that leads from the omega-3 ALA to EPA and DHA uses the very same enzymes as the pathway leading from the omega-6 LA to arachidonic acid. The omega-3 and omega-6 pathways have to share these enzymes, so the pathways actually compete with one another.

This is why some scientists believe that it is important to eat a balance of omega-3 and omega-6 fatty acids. There is good evidence to suggest that our ancestors ate diets that contained roughly equal amounts of omega-3 and omega-6, depending on where they lived; at most their diets may have had 2 to 4 times more omega-6 than omega-3. However, these days our diets contain 20 to 30 times more omega-6 than omega-3, tipping the scale mightily toward inflammation and away from healing. This may be one of the most important reasons why so many people experience chronic pain and inflammation and find themselves turning so often to medications like ibuprofen to turn down the activity of the omega-6 pathway.

The same problem occurs in animals. Grass is high in ALA, the omega-3 parent molecule, whereas grains are high in LA, the omega-6 parent molecule. Therefore, grain-fed cows, for example, have an excess of omega-6 fatty acids and a deficit of omega-3 fatty acids. Grass-fed beef has an average omega-6 to omega-3 ratio of 1.53 to 1, whereas grain-fed beef has a ratio of 7.65 to 1.

If you don’t regularly eat foods naturally rich in omega-3, you should consider taking a supplement. There are three forms of omega-3 fatty acids: ALA, EPA and DHA, and supplements vary greatly in quantities of each form. Aim for about 1000 mg of EPA + DHA (combined—not 1000 mg of each) per day. An example of a good choice for fish oil is Nordic Naturals Ultimate Omega. An example of a good choice for an algae-derived vegetarian/vegan-friendly omega-3 supplement is NuTru Vegan Omega 3 EPA+DHA. [I do not have financial relationships with either of these manufacturers]

Is it possible to eat too much omega-3?

Theoretically, yes. If you ate a diet consisting only of a high-omega-3 fish, such as mackerel or salmon, your omega-6 intake would be very low in comparison to your omega-3, and it is possible that your ratio could turn upside-down. Would that be bad for your health? The theoretical possibilities include increased risk of bleeding and reduced ability to mount an appropriate inflammatory response to injuries and infections. I found two studies that can help us to address this question.

In the first study [Siess et al 1980], researchers fed men a diet consisting of unlimited carbohydrate + mackerel for one week, so that mackerel was the only source of fat or protein. This diet provided 7 to 11 grams of omega-3 fatty acids per day. The number of platelets (blood clotting bodies) in the blood of these men was reduced and platelets were less sticky in laboratory tests compared to platelets of those eating a standard diet. The authors of the study concluded that these were healthy developments, because they could potentially decrease the risk of blood clots in people who are at risk for strokes and heart attacks.

In the second study, researchers compared one diet containing essentially no omega-3 fatty acids, to another diet containing 10 grams per day of omega-3 fatty acids in the form of salmon and salmon oil. After 3 weeks, in the high omega-3 group, platelet counts dropped (in a couple of cases to below normal–the lowest count was 90,000, whereas the normal lower limit is considered to be 150,000), platelets became less sticky, and bleeding time was lengthened to about 10 minutes on average (normal upper limit considered to be about 9 minutes). The authors did not conclude whether these findings meant that the high omega-3 diet was healthier or riskier than the omega-3 free diet.

The typical recommended dose of omega-3 fatty acids is between 1 and 2 grams per day. Since the scientific jury is still out about the potential risks involved in taking very high doses of omega- 3, it would be best to use common sense here. It is nearly impossible to eat a natural diet that is too high in omega-3 and too low in omega-6. However, eating a diet of 100% oily fish (there are no studies of such a diet) or taking very high doses of omega-3 fatty acids could theoretically throw your ratio off-balance to the point that bleeding and resistance to infection could become problematic.

Bottom line about fats

• Healthy fats are healthy for you.
• Include healthy animal fats in your daily diet if you can, as these are naturally good sources of EPA and DHA.
• Reduce the amount of vegetable oils (nut and seed oils) in your diet to improve your omega-3 to omega-6 ratio.
• If you choose to eat a vegan diet, be sure to include some DHA/EPA from microalgae sources, and gravitate towards plant foods that are high in ALA and low in LA.

To learn why dietary cholesterol is not bad for you, read my cholesterol page.

From the 1970’s until very recently, we were told that all fats were bad, and we should eat as little fat as possible. We now know that polyunsaturated omega-3 fatty acids are not only good for us, they are essential. What is the difference between saturated and unsaturated fats? Are some fats “good” and other fats “bad”?

What is fat?

Fats and oils are large molecules made of carbon, hydrogen, and a little bit of oxygen. Each fat molecule contains 3 fatty acid tails attached to a glycerol backbone. The result is called a “triglyceride.” Every fat molecule (or triglyceride) has the same glycerol backbone; it’s the different types of fatty acids attached to that backbone that give different kinds of fats their unique properties. Each fatty acid is essentially a long chain of carbon atoms with lots of hydrogen atoms attached to it along both sides, and an “acid” group on one end.

Fat is good.

We think of fat as bad; as something we want to get rid of. We think that the less we have of it the healthier we are. When we have too much of it, we feel ugly and unhappy. But the truth is that fat is incredibly important. Fat is vital to human life and health.

Fat is our portable battery pack.

Fat is an efficient, lightweight, flexible, and portable source of energy. All animals store energy as fat for these reasons. If we were meant to burn carbohydrates for energy, we would have the ability to sprout big lumps of starch all over our bodies, the way plants do. But Mother Nature is smart. She knows that animals need to move around in the world and can’t afford to be weighed down by heavy potato-like structures. Our bodies can only store hours’ worth of energy as starch (glycogen), but we can store months’ worth of energy as fat.

Fat contains more than twice the amount of energy per pound than carbohydrates do. You probably already know this but may not have thought about it this way: carbohydrate contains 4 calories per gram and fat contains 9 calories per gram. Calories are units of energy. Fat can pack a lot more energy than starch can.

Saturated fat is the preferred fuel of the heart, which is why the heart has some saturated fat wrapped around it.

Our brains are mostly made of fat.

Approximately 60% of the brain is made out of fat. In addition to being an important component of every brain cell membrane, fat also is a major component of myelin, the special insulating material that is wrapped around the electrical wiring pathways of our brain (damage to myelin is the hallmark of Multiple Sclerosis). Myelin is approximately 50% fat and 50% cholesterol.

Fat protects us.

Fat cushions our delicate vital organs so they won’t be bruised or damaged when we run, jump, or fall. Fat is a critical component of our skin—the barrier between us and the outside world—preventing us from randomly absorbing everything we come into contact with. Fats are integral parts of the outer lining (membrane) of every cell in our bodies, forming a water-tight seal that keeps stuff that should be inside the cell inside and stuff that should stay outside of the cell outside. What’s more, inside each cell are mini-compartments, like the nucleus and the mitochondria, that need to keep their contents separate from the inside of the rest of the cell, so they each have fatty membranes, as well.

Fats lubricate our moving parts.

Fats are important ingredients in tears, joint fluids, and other slippery substances that we need to function properly.

Dietary fat is required for vitamin absorption.

Certain essential vitamins, such as A, D, E and K, all require fat in order to be absorbed by our intestines. Fat itself is so important to our health and survival, that we are designed to absorb about 99% of all the fat we eat. This is not true of many plant substances that we think of as so important to our health, such as vegetable iron and beta-carotene.

How much fat do we need to eat?

This is a difficult question. Fat is so important to every cell in our bodies that we can make fat out of anything—we can make it out of dietary proteins from animals and plants, and we can make it out of carbohydrates, like sugar and starch. That doesn’t mean that these are the ideal ways to obtain fats—for all we know, the body would prefer to get its fat directly from the diet so that it doesn’t have to go through the hassle of turning other dietary ingredients into fat—it just means that it’s possible. There are only a few fats (essential fatty acids) that we absolutely must eat because we can’t make them ourselves (see below).

What is the difference between saturated and unsaturated fat?

A saturated fatty acid has the most hydrogen atoms it can possibly carry—it is therefore “saturated” with hydrogen. Every carbon atom is attached to as many hydrogen atoms as it can hold. Each carbon-hydrogen bond carries energy, so the more hydrogen atoms that are bound to a fat, the more energy you can get out of that fat when you burn it. Saturated fat has more energy, and therefore more calories, per pound.

Unsaturated fats have less hydrogen—at least one of the carbons will have a hydrogen missing. Since there is no hydrogen for that carbon to bind to, the carbon atom forms a double bond to a neighboring carbon atom instead. If a fat has one double bond, it is called “monounsaturated” (missing one hydrogen). Oleic acid, the primary fatty acid in olive oil, is a well-known example of a monounsaturated fatty acid, or MUFA. If it has more than one double bond, it is called “polyunsaturated” (missing more than one hydrogen). Omega-3 and omega-6 fatty acids (see below) are well-known examples of polyunsaturated fatty acids, or PUFAs.

Most fats occurring in nature contain mixtures of saturated, monounsaturated, and polyunsaturated fatty acids. Olive oil contains approximately 17% saturated fatty acids, 71% MUFA (oleic acid), and 11% PUFAs. Coconut oil contains more than 90% saturated fat. Beef fat contains nearly equal parts saturated fat and monounsaturated fat (most of which is oleic acid, the primary fatty acid in olive oil) and approximately 5% polyunsaturated fat, depending on what the animal is fed.

Saturated fats, with their full load of energy-packed hydrogen bonds, are straight molecules that stack together efficiently, and are therefore solid at room temperature (like lard, cocoa butter and coconut oil). Unsaturated fats, with their weaker double bonds, are crooked, because double bonds create kinks in the backbone. They do not pack together efficiently and are therefore liquid at room temperature (like olive oil). Imagine a box full of straight straws—they pack easily and you can fit a lot of straws into the box. However you can’t fit as many bendy straws into that same box because they take up more space. They also move around more inside the box.

When molecules have room to move around easily, they are more likely to form liquids than solids. Saturated fats are very stable, whereas unsaturated fats (oils) are fragile. The carbon double bonds in unsaturated fats are weak and vulnerable to chemical attack compared to the strong carbon-hydrogen bonds in saturated fats. This is why unsaturated fats (oils) go rancid (become oxidized) when exposed to air, whereas you can leave lard or butter on the countertop for a long time without worrying about it. Ghee, which is butter with all of its proteins removed (pure butterfat), can be stored at room temperature indefinitely.

Are saturated fats unhealthy?

Our bodies need both types of fats—saturated and unsaturated. Saturated fats are good for things like insulation (myelin), cushioning (abdominal fat around our organs), and storage (body fat under the skin) purposes. Unsaturated fats are good for flexibility and fluidity purposes, such as in membranes and body fluids. It doesn’t make sense to think of one kind as inherently healthy and the other kind as inherently unhealthy.

Saturated fats are chemically rather boring—they are quite stable (especially as compared to the reactive PUFAs) and it is hard from a common sense point of view to imagine them causing the kinds of trouble they are accused of causing—such as burrowing into heart vessel walls and causing inflammatory plaques that rupture into heart attacks. These are by nature long, smooth, non-irritating substances.

You would not want all of your body fat to be unsaturated. All of your fat would be liquid instead of firm and compact. Not only would you sag everywhere, and begin to resemble a Shar Pei, but your body would have to be bigger, because liquid fats take up more space (like the bent straws in the box).

The misguided belief that saturated fats cause heart disease is rooted in a famous study published in 1970 called “The Seven Countries Study,” in which renowned scientist Ancel Keys claimed that people in countries where more animal fat was eaten had more heart disease then people in countries where less animal fat was eaten. Not only was this study an epidemiological study, and therefore incapable of proving a causal link between any dietary factor and any disease, but there have been numerous studies showing no connection at all between saturated fat and heart disease, including a study of 22 countries published by Yerushalmy and Hilleboe in 1957 (see references below).

The hypothesis that saturated fat causes heart disease now stands on very shaky ground; it is now controversial at best, if not obsolete. Researchers are finding much stronger evidence linking cholesterol dysregulation and heart disease to refined carbohydrates than to saturated fats [Halton 2006, Howard 2006, Mente 2009, Astrup 2010, and Jakobsen 2010].

What are omega-3 fatty acids?

Omega-3 fatty acids are polyunsaturated fatty acids (PUFAs). This means they each have more than one carbon double bond in place of a hydrogen atom. Omega-3 just means that the first double bond in the fat chain is at carbon #3 in the backbone. They are liquid fats (oils).

Even if you eat a 100% fat-free diet, your body will find a way to make almost all of the important fats it needs out of the protein and carbohydrate you eat, but it cannot make omega-3 fatty acids. There are three omega-3 fatty acids that are often called “essential” to our health: ALA (alpha-linolenic acid), EPA (eicosapentaenoic acid), and DHA (docosahexaenoic acid). Because we can’t make them from scratch, we have to eat them.

What is ALA?

ALA is the mother of all omega-3 fatty acids. It is an 18-carbon fatty acid that we can build upon to make EPA (20 carbons), which can in turn be converted to DHA (22 carbons). This process happens in the liver. The problem is that our bodies are not very good at adding carbons to ALA, so we convert only a very small percentage (less than 5%) of the ALA we eat into EPA, and far less of that EPA into DHA. So, the vast majority of the ALA we eat does not turn into precious EPA and DHA; it simply gets burned for energy or stored as fat.

It appears as if ALA itself isn’t required by the body as an important component of any particular cell or molecule; it may only be important as a building block for EPA and DHA. Therefore, if you get enough EPA and DHA in your diet, you may not need any ALA.

What are EPA and DHA?

EPA and DHA, on the other hand, serve important roles in the body. I mention them together because they are almost always found together in nature, and because researchers almost always study them in combination, not individually. Therefore, it can be confusing to try to figure out which one of these compounds is responsible for which benefits. Both EPA and DHA serve as building blocks for anti-inflammatory, pro-healing compounds called “resolvins” and “protectins”, which help to prevent chronic inflammation. They also stabilize the electrical activity of cardiac cell membranes, reducing risk of arrhythmias.

It seems as if DHA may be the most essential of the essential omega-3 fatty acids. The brain and retina require large amounts of DHA for their cells to function properly. It is found in the cell membranes of the brain and retina, helping to keep those membranes fluid and flexible. This is important, because membranes don’t simply act as water-tight walls. They have to be able to wrap around and envelop important nutrients to take them in, or fold outward to let them out. Membranes are very dynamic structures. [I wrote an entire post about the critical role of DHA in the brain and how to include it in your diet in my Psychology Today post: “The Brain Needs Animal Fat.”]

What are good dietary sources of ALA?

ALA is easy to obtain because it is found in such a wide variety of plant and animal foods. Interestingly, Americans obtain more of their daily ALA from animal foods than from plant foods. Oils of seeds, grains, nuts, and legumes contain ALA, with the highest concentrations being found in flaxseed oil, walnuts, canola oil and chia seeds. These foods are therefore marketed as being “rich in omega-3s.” There is also a significant amount of ALA in purslane, an edible succulent green vegetable, and small amounts of ALA in spinach leaves.

The problem is that these sources only contain one of the three essential omega-3 fatty acids; they do not contain any DHA or EPA. And the body can only convert a very small percentage of ALA into EPA (3-8%) and has an even harder time converting ALA into DHA (0-4%), although there are some studies that suggest that, in the complete absence of dietary DHA (such as may occur for vegans), the body may be able to ramp up its ability to convert ALA into DHA to some extent.

What are good dietary sources of EPA and DHA?

EPA and DHA are synthesized primarily by algae and grasses—things that people don’t eat and don’t digest well:

• Marine microalgae
• Seaweed
• Grasses

However, many land animals eat grasses (or should) and many fish (especially small fish) eat algae. Animals eating these green foods accumulate EPA and DHA in their tissues, especially in their fats, livers, and brains. Therefore, good sources of EPA and DHA include:

• Meat from grass-fed animals
• Liver from grass-fed animals (much higher amounts than muscle meats)
• Pasture-raised poultry meat
• Liver from pasture-raised poultry (much higher amounts than bird meat)
• Animal brain
• Small oily fish (anchovy, herring, sardines and mackerel)
• Large oily fish that eat small oily fish (bluefish, tuna, salmon, halibut, bass, and trout)—even farmed fish often contain omega-3’s because of what they are fed.
• Fish liver oils, such as cod liver oil.
• Oysters

Eggs from pastured poultry contain some DHA but are a poor source of EPA.

Full-fat dairy products, especially from grass-fed animals, contain some EPA but are a poor source of DHA.

What are omega-6 fatty acids?

Omega-6 fatty acids are liquid polyunsaturated fatty acids (PUFAs) just like omega-3s are, but they have their first double bond at carbon #6 instead of carbon #3. Whereas there are three important omega-3 fatty acids for human health, there is only one essential omega-6 fatty acid: linoleic acid (LA).

What is linoleic acid (LA)?

It is so unfortunate that linoleic acid, the mother of all omega-6 fatty acids, and alpha-linolenic acid, the mother of all omega-3 fatty acids, have such similar names, because many people confuse the two, but so be it. LA is an 18-carbon polyunsaturated omega-6 fatty acid that we can build upon to make other important molecules, most notably, a 20-carbon omega-6 fatty acid called arachidonic acid.

Linoleic acid is present in all of our cell membranes so that it will be available to form arachidonic acid whenever called upon to do so. Arachidonic acid is required for the process of inflammation to begin. You might be thinking that inflammation is a bad thing, but without it, we cannot mount an immune response to things like bacterial infections and physical injuries. Inflammation is our first line of defense and requires specialized molecules that are made from arachidonic acid: prostaglandins, leukotrienes, and thromboxanes.

While you may not have heard of any of those inflammatory chemicals, you have probably heard of the medicines that are marketed to reduce their activity. NSAIDs such as ibuprofen reduce prostaglandin synthesis. Aspirin reduces prostaglandin synthesis and thromboxane activity. Singulair® is an asthma medication that reduces leukotriene activity.

What are good dietary sources of Linoleic Acid?

Our Western diet is loaded with LA, so not to worry. In fact, we get far more LA than we need. Linoleic acid is present in all kinds of plant and animal foods, but it is present in especially high amounts in vegetable oils (nut and seed oils). Animal fats contain approximately 10-20 % LA, whereas seed oils contain between 50-80% LA. We have been told for decades to avoid animal fats and to choose plant oils instead, and the result is that most of us now get far too much LA in our diet.

The omega ratio problem: are you off-balance?

So, the omega-3 fatty acids are used to create chemicals that have anti-inflammatory properties (resolvins, protectins) and the omega-6 fatty acid LA is used primarily to create chemicals that have pro-inflammatory properties (prostaglandins, leukotrienes, and thromboxanes).

All creatures need a proper balance of these two forces in order to defend themselves (pro-inflammatory elements) and heal (anti-inflammatory elements). Mother Nature understood this, which is why we are gifted with both pathways. In fact, these pathways are intricately connected to each other to keep one another in check. It’s a brilliant system. The pathway that leads from the omega-3 ALA to EPA and DHA uses the very same enzymes as the pathway leading from the omega-6 LA to arachidonic acid. The omega-3 and omega-6 pathways have to share these enzymes, so the pathways actually compete with one another.

This is why some scientists believe that it is important to eat a balance of omega-3 and omega-6 fatty acids. There is good evidence to suggest that our ancestors ate diets that contained roughly equal amounts of omega-3 and omega-6, depending on where they lived; at most their diets may have had 2 to 4 times more omega-6 than omega-3. However, these days our diets contain 20 to 30 times more omega-6 than omega-3, tipping the scale mightily toward inflammation and away from healing. This may be one of the most important reasons why so many people experience chronic pain and inflammation and find themselves turning so often to medications like ibuprofen to turn down the activity of the omega-6 pathway.

The same problem occurs in animals. Grass is high in ALA, the omega-3 parent molecule, whereas grains are high in LA, the omega-6 parent molecule. Therefore, grain-fed cows, for example, have an excess of omega-6 fatty acids and a deficit of omega-3 fatty acids. Grass-fed beef has an average omega-6 to omega-3 ratio of 1.53 to 1, whereas grain-fed beef has a ratio of 7.65 to 1.

If you don’t regularly eat foods naturally rich in omega-3, you should consider taking a supplement. There are three forms of omega-3 fatty acids: ALA, EPA and DHA, and supplements vary greatly in quantities of each form. Aim for about 1000 mg of EPA + DHA (combined—not 1000 mg of each) per day. An example of a good choice for fish oil is Nordic Naturals Ultimate Omega. An example of a good choice for an algae-derived vegetarian/vegan-friendly omega-3 supplement is NuTru Vegan Omega 3 EPA+DHA. [I do not have financial relationships with either of these manufacturers]

Is it possible to eat too much omega-3?

Theoretically, yes. If you ate a diet consisting only of a high-omega-3 fish, such as mackerel or salmon, your omega-6 intake would be very low in comparison to your omega-3, and it is possible that your ratio could turn upside-down. Would that be bad for your health? The theoretical possibilities include increased risk of bleeding and reduced ability to mount an appropriate inflammatory response to injuries and infections. I found two studies that can help us to address this question.

In the first study [Siess et al 1980], researchers fed men a diet consisting of unlimited carbohydrate + mackerel for one week, so that mackerel was the only source of fat or protein. This diet provided 7 to 11 grams of omega-3 fatty acids per day. The number of platelets (blood clotting bodies) in the blood of these men was reduced and platelets were less sticky in laboratory tests compared to platelets of those eating a standard diet. The authors of the study concluded that these were healthy developments, because they could potentially decrease the risk of blood clots in people who are at risk for strokes and heart attacks.

In the second study, researchers compared one diet containing essentially no omega-3 fatty acids, to another diet containing 10 grams per day of omega-3 fatty acids in the form of salmon and salmon oil. After 3 weeks, in the high omega-3 group, platelet counts dropped (in a couple of cases to below normal–the lowest count was 90,000, whereas the normal lower limit is considered to be 150,000), platelets became less sticky, and bleeding time was lengthened to about 10 minutes on average (normal upper limit considered to be about 9 minutes). The authors did not conclude whether these findings meant that the high omega-3 diet was healthier or riskier than the omega-3 free diet.

The typical recommended dose of omega-3 fatty acids is between 1 and 2 grams per day. Since the scientific jury is still out about the potential risks involved in taking very high doses of omega- 3, it would be best to use common sense here. It is nearly impossible to eat a natural diet that is too high in omega-3 and too low in omega-6. However, eating a diet of 100% oily fish (there are no studies of such a diet) or taking very high doses of omega-3 fatty acids could theoretically throw your ratio off-balance to the point that bleeding and resistance to infection could become problematic.

Bottom line about fats

• Healthy fats are healthy for you.
• Include healthy animal fats in your daily diet if you can, as these are naturally good sources of EPA and DHA.
• Reduce the amount of vegetable oils (nut and seed oils) in your diet to improve your omega-3 to omega-6 ratio.
• If you choose to eat a vegan diet, be sure to include some DHA/EPA from microalgae sources, and gravitate towards plant foods that are high in ALA and low in LA.

To learn why dietary cholesterol is not bad for you, read my cholesterol page.

Naturally sweet, colorful, and delicious—fruits are the only parts of plants that are specifically designed to be eaten. For those who can tolerate carbohydrate, fruits are the healthiest sources on the planet, but what if you are carbohydrate-sensitive and need to avoid fruit? Don’t you need all those vitamins and antioxidants? What are antioxidants, anyway?

What is fruit?

INGREDIENTS:
Seeds
Sugar alcohols (sorbitol, mannitol, xylitol, etc)
Sugars (fructose, glucose, sucrose)
Soluble Fiber
Phytochemicals

We believe fruits are good for us because they contain fiber, vitamins, and antioxidants. While there is no evidence that humans require fruit in order to be healthy, of all the plant foods you can eat, fruits are the least likely to cause trouble. That’s because fruits are the only parts of the plant that are specifically designed to be eaten.

Since plants need animals like us to eat their fruits, most chemicals in fruits, including fruit antioxidants, are not designed to harm us (vegetables are not so innocent). Most fruits (with the notable exception of a wide variety of poisonous berries) are quite safe to eat whole

Seeds

What all fruits have in common are seeds. This means that some foods we think of as vegetables—cucumbers, tomatoes, squashes—are actually fruits.

Seeds can be large (peach pit) or small (apple seeds). Each seed contains a precious plant embryo (baby plant), which needs to find a fertile spot and grow into an adult plant. Since plants can’t move, they need you (or other creatures) to eat their fruits in order to disperse their seeds.

When you stop to pick an apple from a tree, you will probably eat the fruit and toss the core, with its seeds inside, onto the ground, hopefully somewhere not too close to the tree. This helps the apple tree spread its seeds a little farther away from its trunk, and increases the chances of finding fertile ground; therefore the tree may reproduce more successfully. If a bear snacks on an apple, he will probably eat the whole apple, core and all, in which case the seeds get to take a free ride through the bear’s intestines. By the time the seeds exit the bear, the bear will probably not only be very far away from the tree, but will also deposit the seeds onto the ground complete with a supply of natural fertilizer, as a parting gift.

So, ultimately, the fruit is there to serve the reproductive needs of the plant, and creatures like us are just unsuspecting taxicabs for their seeds.

Sugar alcohols

Plants have evolved over hundreds of millions of years to use animals for their own purposes, and they know what they are doing. Not only have they made most fruits sweet, delicious, and easy to pick, they have also included in the flesh of the fruit sugar alcohols, like sorbitol, mannitol, and xylitol. If you have ever eaten “sugar-free” chocolates or candies that contain sugar alcohols, you know that they can have a laxative effect. This is no accident. Fruits contain sugar alcohols to speed the seed along its route through your body. This is also why prunes, which are high in the sugar alcohol sorbitol, are famous for relieving constipation. Plants want you to transport their seeds, they do not want you to digest and destroy them. The longer it takes for a seed to travel through an animal’s gastrointestinal tract, the higher the chance that it will be damaged in the process, so the plant would like its seeds to move through you as quickly as possible.

Sugars

Plants know we have a sweet tooth, so they include sugars in their fruits. Fruits contain three types of simple sugar: fructose (fruit sugar), glucose (the same sugar we have in our bloodstream), and sucrose (table sugar—which is made from sugar cane and beets). Humans evolved from a fruit-eating primate ancestor, and most human populations have eaten fruit ever since, so we are probably very well-adapted for handling the amount of sugars found in whole fruits. Unfortunately, many of us have developed difficulty processing sugars, probably because we have been eating far too much refined carbohydrate as part of the Western diet for too many years of our lives.

There is a huge difference between eating whole fruits and eating concentrated and added sugars in processed foods and drinks. Fruits contain lots of fiber and water, so they are very filling and satisfying; it’s difficult to overeat fruit without feeling uncomfortable. However, it’s all too easy to drink a liter of fruit juice, eat a pint of ice cream, or polish off a king-sized candy bar. Most of us have not adapted very well to a high refined carbohydrate diet, since it is a relatively new trend in human history.

It is well established that diets high in sugars are unhealthy (see my carbohydrates page), but if you choose to include some sugar in your diet, the healthiest sources of sugar in my opinion are whole fruits—not fruit smoothies, not fruit sauces, not fruit juices, not even dried fruits—these are all much higher in sugar than whole fruits and too easy to overeat.

If you have trouble processing carbohydrate or if you are trying to lose weight, you would be wise to choose low-sugar fruits (such as berries), significantly limit fruit intake, or even avoid fruit entirely.

If you have IBS-D you may want to limit fruits, especially those highest in sugar alcohols.

Soluble fiber

Soluble fiber is a type of carbohydrate that gives fruit its shape. It is the scaffolding of the fruit. Its only purpose is to hold the fruit together.

Phytochemicals (antioxidants)

Since phyto means plant, phytochemicals are just plant chemicals. You’ve probably heard a lot about “phytochemicals” or “phytonutrients” or “phytoestrogens”. We are told that colorful fruits and vegetables contain lots of phytonutrients, and that they are beneficial for our health because they are antioxidants.

What are antioxidants, anyway?

Antioxidants protect living cells from damaging “oxidation.” Oxidative damage is caused by things like radiation (sun rays), and the chemical reactions that naturally take place inside of living cells as part of everyday metabolism. These types of events have the power to remove electrons from stable molecules, thereby generating “reactive oxygen species” (ROS) or “free radicals.” Free radicals are very reactive and unstable, because they are missing an electron (a negatively-charged particle). Molecules like to have a perfect balance of positive and negative charges at all times. So, these free radicals, in their mad search for an electron, will rip off electrons from vulnerable molecules in their path until they are happily balanced again.

So, the original free radicals are now stable (phew), but now we have two new problems:

First problem: when an electron is torn away from a molecule, the molecule can break apart or stop functioning properly.

Second problem: these neighboring molecules are now missing electrons and are now unstable themselves…and so they go looking for electrons…and a chain reaction can occur. If this chain reaction is not stopped, the cell could be damaged beyond repair.

This is why antioxidants are so important. All living things need antioxidants to protect them from the oxidative dangers of daily living. Luckily, Mother Nature provided us with plenty of our own human antioxidants within our bodies, many of which are quite different from plant antioxidants. These include things like uric acid and cholesterol.

Unfortunately, it’s not that simple. Just because a chemical behaves like an antioxidant in a plant, or in a test tube, does not mean that it will behave the same way in our bodies. Many research studies show that plant antioxidants are poorly absorbed by our bodies, changed by our bodies into completely different compounds, or rapidly eliminated:

“Unlike the traditional vitamins, phytochemicals as dietary components are not essential for short-term well-being, and whereas the body has specific mechanisms for the accumulation and retention of vitamins, in contrast, phytochemicals are treated as non-nutrient xenobiotics [foreign substances that shouldn’t be there] and metabolised so as to eliminate them efficiently.” [Crozier 2009]

However, when scientists extract chemicals from fruits and give them to people in unnaturally high doses, they can be harmful. Nature intended us to eat the whole fruit, not purified concentrates of fruit chemicals.

The majority of fruit phytochemicals that you have heard about fall into two categories: the polyphenols and the carotenoids.

Polyphenols (aka flavonoids)

Polyphenols are colorful plant chemicals that share a similar chemical structure. Most of them are just pigments, not toxins, so the polyphenol family is relatively mild-mannered, at least at concentrations found in nature. While you may have heard that these substances have magical anti-inflammatory properties and that they can “boost” your immune system, the truth is that the vast majority of scientific studies have been done in vitro (test tube conditions) and have used doses far too high to be found in nature. Even if polyphenols do have magical healing powers, we are unlikely to benefit from them, because they are poorly absorbed, and transformed by our small intestine, liver, and colon, into completely different substances. Below is a list of the most commonly-encountered fruit polyphenols:

Anthocyanins

These are blue, red, and purple pigments that give fruits like blueberries, cherries, raspberries, strawberries, blackberries, and concord grapes their beautiful colors. They also serve as natural plant sunscreens.

Based on experiments in test tube conditions (in vitro) and in laboratory animals, scientists think anthocyanins may have anti-cancer, anti-inflammatory, and antioxidant properties, but there are no useful human studies yet that can tell us whether or not this is true.

Even if they were miracle molecules, eating bushels of berries would not help you, because less than 0.1% (one in a thousand!) of the anthocyanins you eat make it into your bloodstream, and those that make it disappear within a few hours.

Quercetin

This is the most common polyphenol pigment in the diet; many fruits and vegetables contain at least some quercetin. Capers, cranberries, black currants, apples, grapes, blueberries, and apricots are the fruits that contain the most quercetin.

Of all the polyphenols, quercetin is the easiest to absorb; about 20% of what you eat will make it into your bloodstream, but it only lasts a few hours.

There have been some human studies that suggest possible anti-inflammatory and anti-oxidant effects for quercetin. However, the doses that are used in these studies are impossible to get from food. There are currently no clinical trials of quercetin as a cancer treatment drug. [Read my post “Foods that Cause Hypothyroidism” to learn how quercetin can interfere with thyroid function.]

Resveratrol

Resveratrol is found in a variety of fruits, including blueberries and cranberries, and also in peanuts, but grape skins contain the most resveratrol, and are the most famous example. For a more in-depth look at the proposed health benefits of the resveratrol in red wine, read my Psychology Today post: “Can Red Wine Reduce Your Risk for Alzheimer’s?“

Resveratrol is not a pigment (pure resveratrol is white). Plants use resveratrol to prevent fungus from infecting their fruits, therefore it is a fungicide.

Tannins

These are more common in vegetables than fruits, but some fruits, like grapes, persimmons and blueberries, do contain tannins, as do apple skins and pear skins. Tannins are bitter and have an astringent quality (they make your mouth feel dry).

Tannins are tannish-white in color but are not pigments; they are defensive chemicals designed to protect plants from harsh weather and all kinds of predators.

Tannins are destroyed in the drying process, so dried fruits (like raisins) do not contain tannins. Cooking reduces the amount of tannins in foods.

Tannins are hard to absorb; most tannins make it all the way to the colon (towards the very end of the digestive tract) without being absorbed, and by that time, most of them have been changed into different molecules by the digestive process.

Tannins have the ability to bind to proteins, which is what makes them good for tanning leather (this is how they got their name). However, this same power to bind proteins means that tannins can bind to proteins in our digestive tract. Since our digestive enzymes are proteins, tannins can interfere with proper digestion of foods, especially proteins.

Tannins also interfere with our ability to absorb “non-heme iron”, which is the form of iron found in plant foods. They do not interfere with our ability to absorb “heme” iron, which comes from animal foods.

Some tannins behave like antioxidants under test tube conditions (in vitro) but this hasn’t been proven in living systems (in vivo). Some tannins have antibiotic (bacteria-killing) and antiviral properties. A few animal studies suggest that tannins may be helpful in cases of diabetes and heart disease, but there have been no clinical studies yet. Some in vitro studies suggest possible anti-cancer activity, but there have been no clinical studies in humans.

In my post “Cranberries for UTI Prevention: Crimson Crusader or Juicy Gossip?” I provide a more detailed analysis of where the science stands in relation to the claim that the tannins in cranberries can prevent urinary tract infections.

In laboratory studies (in vitro), tannins have been shown to interfere with the activity of an important enzyme called Topoisomerase II. This enzyme is required for DNA to function properly. This makes sense because plants use tannins to protect themselves against predators. However there are no studies available to prove or disprove this activity in humans (in vivo).

Carotenoids

Carotenoids are red/orange/yellow pigments that come in various forms, the most famous one being beta-carotene. Most carotenoids come from vegetables such as carrots and sweet potatoes, and in fruits that we think of as vegetables (such as pumpkins and squashes—see my post: “Are Pumpkins Cancer-Squashing Superfoods?“). However, there is one carotenoid that is famous for being found in fruits—lycopene.

Lycopene

Lycopene is a bright red pigment found in watermelon, guava, pink grapefruit, papaya, pomegranate and tomatoes. Unlike many other carotenoids, lycopene possesses no Vitamin A activity.

We are just lousy at absorbing carotenoids, especially lycopene, from raw foods. Only about 1% of the lycopene from a raw carrot makes it into your bloodstream! This is because the tough cellulose (fiber) of the plant’s cell walls is in the way. Cooking helps to free the lycopene from the food, but it also can reduce the amount of lycopene in the food. Eating fat with lycopene helps absorption. When eaten with some fat, people absorb an average of 5 mg of the lycopene from cooked foods, regardless of how much of the food they eat.

So, is lycopene good for you? Scientists would have us believe that it can help protect us from heart disease and cancer. However:

Studies in humans looking at lycopene and its effects on heart disease have produced conflicting results.

Most of the studies looking at the potential for lycopene to reduce cancer risk have been negative. The FDA reviewed the evidence and concluded that:

“there was no credible evidence to support qualified health claims for tomatoes or tomato-based foods and a reduced risk for lung, colorectal, breast, cervical, or endometrial cancer. FDA further concluded that there was no credible evidence to support qualified health claims for lycopene, as a food ingredient, component of food, or as a dietary supplement, and a reduced risk of any of these cancers… there was very limited credible evidence for qualified health claims for tomatoes and/or tomato sauce and a reduced risk for prostate, gastric, ovarian, and pancreatic cancers provided that the qualified health claims were appropriately worded so as to not mislead consumers.” [Kavanaugh 2007]

Cyanogenic glycosides

These innocent chemicals are mainly found lurking deep inside the rugged pits of certain fruits, such as apricots, peaches, cherries, mangoes, and plums. These types of seeds are virtually indestructible without tools, and it’s a good thing we can’t chew them open. When these seeds are damaged, the nontoxic glycosides mix with an activating enzyme and poof—you’ve got cyanide. Other foods that can generate cyanide include: bitter almonds, marzipan, bamboo shoots, cassava root (tapioca), lima beans, sorghum, apple seeds and pear seeds. Luckily, proper processing of these foods by grinding, boiling and soaking can remove the cyanide and make them safe to eat.

The human body can detoxify tiny quantities of cyanide, but at higher doses, cyanide can interfere with iodine within your thyroid gland and cause goiter or hypothyroidism. At higher doses still, cyanide can suffocate your mitochondria (your cells’ energy generators), which can be fatal.

Glycoalkaloids

Glycoalkaloids are produced by nightshades—eggplants, tomatoes, peppers, white potatoes, tobacco, and goji berries. People think of most of these as vegetables, even though most of them are fruits because they have seeds. These compounds will be explored in the vegetables section of the site.

The bottom line about fruit

• Fruits, though delicious, are not required in the human diet.
• The specialized plant chemicals found in most edible fruits are far less likely to bother most people than those found in vegetables.
• There is no clear evidence that the naturally-occurring phytochemical antioxidants in fruits are beneficial to human health. In fact, some of these chemicals, particularly in concentrated forms, are potentially harmful.
• Due to sugar and sugar alcohol content, many people may need to limit how much fruit they eat. However, if you do choose to include some sugar in your diet, whole fruits are the safest sources of simple sugars available in nature.
• If you are at a healthy weight, do not have IBS-D, and do not have diabetes or any other carbohydrate-related health conditions, you are likely to be able to safely enjoy fruit.

Naturally sweet, colorful, and delicious—fruits are the only parts of plants that are specifically designed to be eaten. For those who can tolerate carbohydrate, fruits are the healthiest sources on the planet, but what if you are carbohydrate-sensitive and need to avoid fruit? Don’t you need all those vitamins and antioxidants? What are antioxidants, anyway?

What is fruit?

INGREDIENTS:
Seeds
Sugar alcohols (sorbitol, mannitol, xylitol, etc)
Sugars (fructose, glucose, sucrose)
Soluble Fiber
Phytochemicals

We believe fruits are good for us because they contain fiber, vitamins, and antioxidants. While there is no evidence that humans require fruit in order to be healthy, of all the plant foods you can eat, fruits are the least likely to cause trouble. That’s because fruits are the only parts of the plant that are specifically designed to be eaten.

Since plants need animals like us to eat their fruits, most chemicals in fruits, including fruit antioxidants, are not designed to harm us (vegetables are not so innocent). Most fruits (with the notable exception of a wide variety of poisonous berries) are quite safe to eat whole

Seeds

What all fruits have in common are seeds. This means that some foods we think of as vegetables—cucumbers, tomatoes, squashes—are actually fruits.

Seeds can be large (peach pit) or small (apple seeds). Each seed contains a precious plant embryo (baby plant), which needs to find a fertile spot and grow into an adult plant. Since plants can’t move, they need you (or other creatures) to eat their fruits in order to disperse their seeds.

When you stop to pick an apple from a tree, you will probably eat the fruit and toss the core, with its seeds inside, onto the ground, hopefully somewhere not too close to the tree. This helps the apple tree spread its seeds a little farther away from its trunk, and increases the chances of finding fertile ground; therefore the tree may reproduce more successfully. If a bear snacks on an apple, he will probably eat the whole apple, core and all, in which case the seeds get to take a free ride through the bear’s intestines. By the time the seeds exit the bear, the bear will probably not only be very far away from the tree, but will also deposit the seeds onto the ground complete with a supply of natural fertilizer, as a parting gift.

So, ultimately, the fruit is there to serve the reproductive needs of the plant, and creatures like us are just unsuspecting taxicabs for their seeds.

Sugar alcohols

Plants have evolved over hundreds of millions of years to use animals for their own purposes, and they know what they are doing. Not only have they made most fruits sweet, delicious, and easy to pick, they have also included in the flesh of the fruit sugar alcohols, like sorbitol, mannitol, and xylitol. If you have ever eaten “sugar-free” chocolates or candies that contain sugar alcohols, you know that they can have a laxative effect. This is no accident. Fruits contain sugar alcohols to speed the seed along its route through your body. This is also why prunes, which are high in the sugar alcohol sorbitol, are famous for relieving constipation. Plants want you to transport their seeds, they do not want you to digest and destroy them. The longer it takes for a seed to travel through an animal’s gastrointestinal tract, the higher the chance that it will be damaged in the process, so the plant would like its seeds to move through you as quickly as possible.

Sugars

Plants know we have a sweet tooth, so they include sugars in their fruits. Fruits contain three types of simple sugar: fructose (fruit sugar), glucose (the same sugar we have in our bloodstream), and sucrose (table sugar—which is made from sugar cane and beets). Humans evolved from a fruit-eating primate ancestor, and most human populations have eaten fruit ever since, so we are probably very well-adapted for handling the amount of sugars found in whole fruits. Unfortunately, many of us have developed difficulty processing sugars, probably because we have been eating far too much refined carbohydrate as part of the Western diet for too many years of our lives.

There is a huge difference between eating whole fruits and eating concentrated and added sugars in processed foods and drinks. Fruits contain lots of fiber and water, so they are very filling and satisfying; it’s difficult to overeat fruit without feeling uncomfortable. However, it’s all too easy to drink a liter of fruit juice, eat a pint of ice cream, or polish off a king-sized candy bar. Most of us have not adapted very well to a high refined carbohydrate diet, since it is a relatively new trend in human history.

It is well established that diets high in sugars are unhealthy (see my carbohydrates page), but if you choose to include some sugar in your diet, the healthiest sources of sugar in my opinion are whole fruits—not fruit smoothies, not fruit sauces, not fruit juices, not even dried fruits—these are all much higher in sugar than whole fruits and too easy to overeat.

If you have trouble processing carbohydrate or if you are trying to lose weight, you would be wise to choose low-sugar fruits (such as berries), significantly limit fruit intake, or even avoid fruit entirely.

If you have IBS-D you may want to limit fruits, especially those highest in sugar alcohols.

Soluble fiber

Soluble fiber is a type of carbohydrate that gives fruit its shape. It is the scaffolding of the fruit. Its only purpose is to hold the fruit together.

Phytochemicals (antioxidants)

Since phyto means plant, phytochemicals are just plant chemicals. You’ve probably heard a lot about “phytochemicals” or “phytonutrients” or “phytoestrogens”. We are told that colorful fruits and vegetables contain lots of phytonutrients, and that they are beneficial for our health because they are antioxidants.

What are antioxidants, anyway?

Antioxidants protect living cells from damaging “oxidation.” Oxidative damage is caused by things like radiation (sun rays), and the chemical reactions that naturally take place inside of living cells as part of everyday metabolism. These types of events have the power to remove electrons from stable molecules, thereby generating “reactive oxygen species” (ROS) or “free radicals.” Free radicals are very reactive and unstable, because they are missing an electron (a negatively-charged particle). Molecules like to have a perfect balance of positive and negative charges at all times. So, these free radicals, in their mad search for an electron, will rip off electrons from vulnerable molecules in their path until they are happily balanced again.

So, the original free radicals are now stable (phew), but now we have two new problems:

First problem: when an electron is torn away from a molecule, the molecule can break apart or stop functioning properly.

Second problem: these neighboring molecules are now missing electrons and are now unstable themselves…and so they go looking for electrons…and a chain reaction can occur. If this chain reaction is not stopped, the cell could be damaged beyond repair.

This is why antioxidants are so important. All living things need antioxidants to protect them from the oxidative dangers of daily living. Luckily, Mother Nature provided us with plenty of our own human antioxidants within our bodies, many of which are quite different from plant antioxidants. These include things like uric acid and cholesterol.

Unfortunately, it’s not that simple. Just because a chemical behaves like an antioxidant in a plant, or in a test tube, does not mean that it will behave the same way in our bodies. Many research studies show that plant antioxidants are poorly absorbed by our bodies, changed by our bodies into completely different compounds, or rapidly eliminated:

“Unlike the traditional vitamins, phytochemicals as dietary components are not essential for short-term well-being, and whereas the body has specific mechanisms for the accumulation and retention of vitamins, in contrast, phytochemicals are treated as non-nutrient xenobiotics [foreign substances that shouldn’t be there] and metabolised so as to eliminate them efficiently.” [Crozier 2009]

However, when scientists extract chemicals from fruits and give them to people in unnaturally high doses, they can be harmful. Nature intended us to eat the whole fruit, not purified concentrates of fruit chemicals.

The majority of fruit phytochemicals that you have heard about fall into two categories: the polyphenols and the carotenoids.

Polyphenols (aka flavonoids)

Polyphenols are colorful plant chemicals that share a similar chemical structure. Most of them are just pigments, not toxins, so the polyphenol family is relatively mild-mannered, at least at concentrations found in nature. While you may have heard that these substances have magical anti-inflammatory properties and that they can “boost” your immune system, the truth is that the vast majority of scientific studies have been done in vitro (test tube conditions) and have used doses far too high to be found in nature. Even if polyphenols do have magical healing powers, we are unlikely to benefit from them, because they are poorly absorbed, and transformed by our small intestine, liver, and colon, into completely different substances. Below is a list of the most commonly-encountered fruit polyphenols:

Anthocyanins

These are blue, red, and purple pigments that give fruits like blueberries, cherries, raspberries, strawberries, blackberries, and concord grapes their beautiful colors. They also serve as natural plant sunscreens.

Based on experiments in test tube conditions (in vitro) and in laboratory animals, scientists think anthocyanins may have anti-cancer, anti-inflammatory, and antioxidant properties, but there are no useful human studies yet that can tell us whether or not this is true.

Even if they were miracle molecules, eating bushels of berries would not help you, because less than 0.1% (one in a thousand!) of the anthocyanins you eat make it into your bloodstream, and those that make it disappear within a few hours.

Quercetin

This is the most common polyphenol pigment in the diet; many fruits and vegetables contain at least some quercetin. Capers, cranberries, black currants, apples, grapes, blueberries, and apricots are the fruits that contain the most quercetin.

Of all the polyphenols, quercetin is the easiest to absorb; about 20% of what you eat will make it into your bloodstream, but it only lasts a few hours.

There have been some human studies that suggest possible anti-inflammatory and anti-oxidant effects for quercetin. However, the doses that are used in these studies are impossible to get from food. There are currently no clinical trials of quercetin as a cancer treatment drug. [Read my post “Foods that Cause Hypothyroidism” to learn how quercetin can interfere with thyroid function.]

Resveratrol

Resveratrol is found in a variety of fruits, including blueberries and cranberries, and also in peanuts, but grape skins contain the most resveratrol, and are the most famous example. For a more in-depth look at the proposed health benefits of the resveratrol in red wine, read my Psychology Today post: “Can Red Wine Reduce Your Risk for Alzheimer’s?“

Resveratrol is not a pigment (pure resveratrol is white). Plants use resveratrol to prevent fungus from infecting their fruits, therefore it is a fungicide.

Tannins

These are more common in vegetables than fruits, but some fruits, like grapes, persimmons and blueberries, do contain tannins, as do apple skins and pear skins. Tannins are bitter and have an astringent quality (they make your mouth feel dry).

Tannins are tannish-white in color but are not pigments; they are defensive chemicals designed to protect plants from harsh weather and all kinds of predators.

Tannins are destroyed in the drying process, so dried fruits (like raisins) do not contain tannins. Cooking reduces the amount of tannins in foods.

Tannins are hard to absorb; most tannins make it all the way to the colon (towards the very end of the digestive tract) without being absorbed, and by that time, most of them have been changed into different molecules by the digestive process.

Tannins have the ability to bind to proteins, which is what makes them good for tanning leather (this is how they got their name). However, this same power to bind proteins means that tannins can bind to proteins in our digestive tract. Since our digestive enzymes are proteins, tannins can interfere with proper digestion of foods, especially proteins.

Tannins also interfere with our ability to absorb “non-heme iron”, which is the form of iron found in plant foods. They do not interfere with our ability to absorb “heme” iron, which comes from animal foods.

Some tannins behave like antioxidants under test tube conditions (in vitro) but this hasn’t been proven in living systems (in vivo). Some tannins have antibiotic (bacteria-killing) and antiviral properties. A few animal studies suggest that tannins may be helpful in cases of diabetes and heart disease, but there have been no clinical studies yet. Some in vitro studies suggest possible anti-cancer activity, but there have been no clinical studies in humans.

In my post “Cranberries for UTI Prevention: Crimson Crusader or Juicy Gossip?” I provide a more detailed analysis of where the science stands in relation to the claim that the tannins in cranberries can prevent urinary tract infections.

In laboratory studies (in vitro), tannins have been shown to interfere with the activity of an important enzyme called Topoisomerase II. This enzyme is required for DNA to function properly. This makes sense because plants use tannins to protect themselves against predators. However there are no studies available to prove or disprove this activity in humans (in vivo).

Carotenoids

Carotenoids are red/orange/yellow pigments that come in various forms, the most famous one being beta-carotene. Most carotenoids come from vegetables such as carrots and sweet potatoes, and in fruits that we think of as vegetables (such as pumpkins and squashes—see my post: “Are Pumpkins Cancer-Squashing Superfoods?“). However, there is one carotenoid that is famous for being found in fruits—lycopene.

Lycopene

Lycopene is a bright red pigment found in watermelon, guava, pink grapefruit, papaya, pomegranate and tomatoes. Unlike many other carotenoids, lycopene possesses no Vitamin A activity.

We are just lousy at absorbing carotenoids, especially lycopene, from raw foods. Only about 1% of the lycopene from a raw carrot makes it into your bloodstream! This is because the tough cellulose (fiber) of the plant’s cell walls is in the way. Cooking helps to free the lycopene from the food, but it also can reduce the amount of lycopene in the food. Eating fat with lycopene helps absorption. When eaten with some fat, people absorb an average of 5 mg of the lycopene from cooked foods, regardless of how much of the food they eat.

So, is lycopene good for you? Scientists would have us believe that it can help protect us from heart disease and cancer. However:

Studies in humans looking at lycopene and its effects on heart disease have produced conflicting results.

Most of the studies looking at the potential for lycopene to reduce cancer risk have been negative. The FDA reviewed the evidence and concluded that:

“there was no credible evidence to support qualified health claims for tomatoes or tomato-based foods and a reduced risk for lung, colorectal, breast, cervical, or endometrial cancer. FDA further concluded that there was no credible evidence to support qualified health claims for lycopene, as a food ingredient, component of food, or as a dietary supplement, and a reduced risk of any of these cancers… there was very limited credible evidence for qualified health claims for tomatoes and/or tomato sauce and a reduced risk for prostate, gastric, ovarian, and pancreatic cancers provided that the qualified health claims were appropriately worded so as to not mislead consumers.” [Kavanaugh 2007]

Cyanogenic glycosides

These innocent chemicals are mainly found lurking deep inside the rugged pits of certain fruits, such as apricots, peaches, cherries, mangoes, and plums. These types of seeds are virtually indestructible without tools, and it’s a good thing we can’t chew them open. When these seeds are damaged, the nontoxic glycosides mix with an activating enzyme and poof—you’ve got cyanide. Other foods that can generate cyanide include: bitter almonds, marzipan, bamboo shoots, cassava root (tapioca), lima beans, sorghum, apple seeds and pear seeds. Luckily, proper processing of these foods by grinding, boiling and soaking can remove the cyanide and make them safe to eat.

The human body can detoxify tiny quantities of cyanide, but at higher doses, cyanide can interfere with iodine within your thyroid gland and cause goiter or hypothyroidism. At higher doses still, cyanide can suffocate your mitochondria (your cells’ energy generators), which can be fatal.

Glycoalkaloids

Glycoalkaloids are produced by nightshades—eggplants, tomatoes, peppers, white potatoes, tobacco, and goji berries. People think of most of these as vegetables, even though most of them are fruits because they have seeds. These compounds will be explored in the vegetables section of the site.

The bottom line about fruit

• Fruits, though delicious, are not required in the human diet.
• The specialized plant chemicals found in most edible fruits are far less likely to bother most people than those found in vegetables.
• There is no clear evidence that the naturally-occurring phytochemical antioxidants in fruits are beneficial to human health. In fact, some of these chemicals, particularly in concentrated forms, are potentially harmful.
• Due to sugar and sugar alcohol content, many people may need to limit how much fruit they eat. However, if you do choose to include some sugar in your diet, whole fruits are the safest sources of simple sugars available in nature.
• If you are at a healthy weight, do not have IBS-D, and do not have diabetes or any other carbohydrate-related health conditions, you are likely to be able to safely enjoy fruit.

Meat has a bad reputation. Most people think of meat, especially red meat, as dangerously unhealthy. However, meat has unique properties that make it more nutritious, easier to digest, and less likely to irritate your body than vegetables. Does the science behind meat-phobia hold up under the microscope?

Is red meat less healthy than other kinds of meat?

Meat is made of animal muscle fibers, which come in two major types: fast and slow. Dark muscle fibers (“slow” fibers) are designed for endurance activities, whereas light muscle fibers (“quick” fibers) are designed for rapid bursts of activity and tire easily. Therefore, dark muscle fibers have greater energy needs. For muscles to make energy, they need an energy source (fat), oxygen to burn the fat, and vitamins and minerals to run the reactions that release the energy from the fat. Therefore, dark meats usually contain more more fat, vitamins and minerals than light/white meats.

To hold the oxygen, dark (slow) muscle fibers need larger amounts of an oxygen carrier protein called myoglobin. Myoglobin is red, which is why red meat is red. Myoglobin is rich in iron, the mineral that binds oxygen, so red meats contain more iron than white meats. Because most dark meats contain more fat than light meats, they can be higher in calories. However, because dark meats also contain more minerals and B vitamins, they are actually more nutritious than light meats.

Did you know that all types of meat—red, light, and white—whether from mammals, birds, or fish—contain about the same amount of cholesterol? There is no more cholesterol in a pound of steak than in a pound of chicken.

But doesn’t red meat increase risk of death?

A study conducted at the Harvard School of Public Health [Pan 2012] claimed that eating red meat increases our risk of death from all kinds of diseases, including heart disease and cancer. This was an epidemiological study, which, by its very nature, is incapable of proving cause and effect; therefore, even if it were the best epidemiological study ever done on the planet, it would be impossible for the authors to conclude that red meat causes death.

Below are just two of the problems I noticed in this study:

1. There were two huge groups of people in this study: the Nurses’ Health Study (over 120,000 women) and the Health Professionals Follow-up study (over 50,000 men). Every 2 years, the nurses were asked how often they had eaten red meat over the past 2 years. Every 4 years, the male health professionals were asked how often they had eaten red meat over the previous 12 months. Can you imagine? Even though I keep track of what I eat in a daily food record, if you asked me what I ate LAST WEEK (never mind 1 to 2 years ago), I honestly couldn’t tell you. Naturally, these questionnaires can’t tell us how often people forget, underestimate, or perhaps even lie about what they were actually eating.
2. It just so happened that the people who reported eating the most red meat per day, also happened to be more likely to:

• smoke cigarettes
• be sedentary
• weigh more
• have diabetes
• take aspirin
• eat more calories per day
• drink more alcohol
• eat more dairy products

These are all excellent examples of what researchers call “confounding variables.” Confounding—translation? Confusing. Even if all of the data are accurate, how can we really know whether the people who ate more red meat were more likely to die because of the red meat, or because of one or more of these other issues?

For a more detailed critique of this study, please see Gary Taubes’ excellent blogpost, entitled “Science, Pseudoscience, Nutritional Epidemiology, and Meat.”

Are saturated fat and cholesterol bad for my heart?

Numerous studies by cardiology researchers have finally disproved the myths that dietary fat, meat, and cholesterol cause heart disease. In fact, some of the healthiest diets in human history have been very high in meat and animal fat. To read more about this topic, please see my post “The History of All-Meat Diets.” We have been eating animal meats, animal fat, and cholesterol for about two million years, but heart disease has only been a major problem for us for about 50 years. The major culprit is therefore much more likely to be something that is NEW in our diets; the current evidence points most strongly to refined and high glycemic index carbohydrates, not fat, meat, or cholesterol. To read more about how sugar raises “bad” cholesterol levels and why dietary cholesterol is not bad for you, please see my cholesterol page. To read more about the connection between sugar, insulin resistance, and heart disease, please see my post “Why Sugar is Bad For You: A Summary of the Research.” To see an example of how researchers desperately twist logic in an effort to connect red meat to heart disease, please see my post “Does Carnitine From Red Meat Cause Heart Disease?“

Does red meat cause cancer?

If meat is so carcinogenic, why was cancer so uncommon until the last century or so? We are not eating any more meat now than we did a hundred years ago, yet cancer incidence is skyrocketing. So, why do we believe that meat causes cancer?

There have been numerous research studies claiming to tie red meat to cancer (particularly colon cancer), however, these were weak epidemiological studies, and are not representative of results in the field as a whole. The fact is that studies of meat and cancer yield very mixed results. Many studies show no connection at all between meat and cancer, and some studies even show a protective benefit. There is simply no solid scientific evidence to support the belief that red meat increases cancer risk.

This did not stop the World Health Organization (WHO) from proclaiming to the planet in October 2015 that red and processed meats cause cancer. Unfortunately, the WHO report is all smoke and mirrors. To see what I mean, please read my detailed analysis of the WHO report: “WHO Says Meat Causes Cancer?“

Charred meats and cancer

Charred meats and wood-smoked meats contain “PAHs” (polycyclic aromatic hydrocarbons) and “HCAs” (heterocyclic amines). PAHs and HCAs have been shown to cause cancer in lab animals. Studies in humans are limited to epidemiological studies, and even these have been inconclusive.

PAHs are present not just in charred meats, but also in anything organic (plant/animal matter) that has been burned–from cigarettes to forest fire smoke to automobile exhaust. PAHs are also present in many other foods, such as cereals, vegetable oils, cheese, and coffee. In fact, cereal products, not meats, are the biggest sources of PAHs in the typical diet.

HCAs, on the other hand, can only be formed from protein-rich foods, such as meat, fish, and poultry.

Grilled and fried chicken can contain even higher amounts of PAHs and HCAs than grilled red meats, yet studies have shown no connection between poultry intake and cancer.

Nitrates and nitrites in processed meats

Nitrates and nitrites are used in the production of processed meats like bacon, salami, and ham. However, they are also found naturally in many plant foods, often in very high amounts. For example, pound for pound, spinach contains at least 30 times more of these compounds than hot dogs do (see table to the left1). In fact, some manufacturers of processed meats boast that they use celery powder (very high in nitrate), instead of the more commonly used sodium nitrite to preserve their meats.

What is the difference between nitrates and nitrites? It can be confusing because these terms are often used interchangeably by food manufacturers, physicians, and nutritionists. The reason why people lump them together so often is because nitrates easily turn into nitrites in foods and in the body. Nitrates and nitrites are very similar chemical salts with very similar properties, and mixtures of nitrates and nitrites are often used in food processing. Nitrites are about three times more potent than nitrates as preservatives.

In combination with salt, nitrates and nitrites prevent the growth of the bacteria that causes botulism (a type of food poisoning). They also act as antioxidants, keeping the fat in the meat from turning rancid, and giving the meat an unnatural pink color. Nitrates and nitrites themselves have not been shown to cause cancer; however, they can react with proteins in the meat to form nitrosamines, which are known to cause cancer in laboratory animals. The addition of special antioxidants during processing cuts down on this chemical reaction and reduces the amount of nitrosamine formed, but doesn’t eliminate it completely. Therefore it is best to choose fresh, unprocessed meats when possible.

It may also be wise to limit intake of vegetables that are very high in nitrates, such as spinach and celery. Bacteria in our saliva convert vegetable nitrates into nitrites, which we swallow. These nitrites can then react with proteins in our stomach to form nitrosamines, exactly the same way they do during meat processing. These nitrosamines are potential carcinogens; this is why some researchers believe that diets high in nitrates are associated with increasing rates of stomach cancer.

Will animal protein damage my kidneys?

To the best of my knowledge, there’s no clinical trial evidence for it so far. The human kidney is designed to be able to handle large quantities of animal protein, perhaps because our ancestors would have sometimes needed to eat large amounts of meat at one sitting, instead of eating smaller portions several times per day every day, the way we modern people do.

The vast majority of studies suggesting a connection between high protein intake and kidney damage have been conducted on laboratory animals or have been epidemiological studies. A 2011 review of the research [Odermatt] examining the connection between diet and kidney disease cited only a single human clinical trial designed to explore this question, and the results were very reassuring:

“Serum creatinine levels and estimated glomerular filtration rate did not change in individuals with normal renal function after 1 yr of a low-carbohydrate diet with higher protein (35% kcal from protein compared with 24%) and fat intake (61% compared with 30%).”

A study done in 1930 of two men who ate a 100% meat diet for a full year revealed no signs of kidney problems whatsoever. [McLellan]

Meat is the only nutritionally complete food

Animal foods (particularly when organ meats are included) contain all of the protein, fat, vitamins and minerals that humans need to function. They contain absolutely everything we need in just the right proportions. That makes sense, because for most of human history, these would have been the only foods available just about everywhere on the planet in all seasons.

Below you can see that animal products are superior sources of most essential vitamins and minerals, including 4 that do not exist in plant foods at all:

Meat nutrients are ready-to-use.

In contrast to vegetables, meat does not contain any “anti-nutrients”, like cellulose, phytates and tannins that interfere with digestion or absorption of vital compounds such as vitamins and minerals.

The forms of vitamins and minerals in meat are the easiest forms to absorb:

• “Heme” iron, the form of iron found in meat, is at least 3 times more available to our bodies than “non-heme” (vegetable) iron.
• Vitamin A from animal sources is 12 to 24 times more available to us than vegetarian sources.
• Vitamins B12 and K2 are only found in animal foods.

Meat is naturally low in carbohydrate

This means that it is impossible to eat meat and generate a significant insulin spike. Insulin spikes are to be avoided as much as possible, as they seriously destabilize our brain and body chemistry and can lead to inflammation, cell damage, disruption of cholesterol and fat metabolism, and numerous chronic diseases.

Meat is gentle on your delicate system.

While vegetables protect themselves with chemicals that are potentially harmful to our cells, animals protect their meat with claws and fangs, so meat itself does not contain any irritating substances. Meat is an especially friendly choice if you tend to be chemically sensitive.

Is meat hard to digest?

Quite the opposite. Meat is efficiently broken down by our own natural enzymes, so we do not need to rely on intestinal bacteria to help us digest it. This means that there are virtually no intestinal gases produced in the process. Meat is efficiently absorbed by our intestines, so there is very little wasted. The belief that meat contributes to constipation is a myth. Unless you have a specific sensitivity to a certain type of meat, you will have no trouble digesting it. Meat can, however, become “trapped” in your digestive tract behind sluggish high-fiber plant foods and dairy products, which are very difficult to digest.

What about meat and gout?

Please see my blog article: “Got Gout but Love Meat?“

Can eating meat cause iron overload?

I find no evidence in the scientific or medical literature linking meat consumption to iron overload. It is true that too much iron can be toxic to cells, and it is true that the body has no way to get rid of excess iron other than through the shedding of skin and intestinal cells or through bleeding. However, the body is very smart and knows not to absorb too much iron. The liver releases a hormone called hepcidin which monitors our iron status and tells our intestinal cells exactly how much iron to absorb. On average, we lose 1 to 3 mg of iron per day, so this is approximately how much we absorb.

Every article I found about iron overload in humans, including an excellent 2012 review in the New England Journal of Medicine, had to do with health conditions that disrupt normal iron metabolism, not with simple overindulgence in red meat. These include hemochromatosis and other genetic disorders of iron metabolism, certain enzyme deficiency disorders, liver disease (alcohol-induced liver damage, viral hepatitis), multiple blood transfusions, and iron supplement overdose (as opposed to red meat overdose). There is also a common non-genetic health problem that can disrupt normal iron processing in the liver called “dysmetabolic hyperferritinemia.” DH is seen in some individuals who have severe metabolic syndrome, usually with fatty liver. While iron deficiency is a very common diet-related condition, diet-induced iron overload does not seem to exist in otherwise healthy people.

What types of meat are healthiest to eat?

Healthy, naturally-raised animals fed their natural diets produce meats with healthier fat profiles, including higher levels of essential omega-3 fatty acids than grain-fed animals.

Avoid factory-farmed, grain-fed animals when you can. Whenever possible and affordable, choose meat products from naturally-raised animals. This means animals that have been fed a diet most similar to what they would eat if they were living in the wild:

• Cows/Lambs/Sheep—grasses
• Chickens—grasses, insects, worms
• Turkeys—grasses, insects, seeds, small animals
• Ducks/geese—fish, grass, algae, insects, fruits
• Pigs— grasses, root vegetables, fruits, nuts, insects, worms, small animals
• Fish—wild, not farmed. Food varies depending on species.

Poultry sellers often boast that their birds are fed an all-vegetarian diet, but if you notice above, birds are naturally omnivores and eat small creatures for protein and fat (worms and insects, for example). This is why backyard birds enjoy suet (animal fat) in the wintertime—insects and worms are scarce in winter and they need the fat and protein for energy.

Does Meat Quality Matter?

It is best for human health, environmental health and animal health and welfare reasons to choose meats raised humanely and sustainably from healthy animals being fed a species-appropriate diet: pasture-raised land animals, wild-caught seafood and wild game. However, not everyone can afford or consistently access animal foods that meet all of these criteria.

Purchasing meat, poultry, and eggs from local community supported agriculture organizations or from responsible online seafood, poultry and red meat distributors can be a reasonably cost-effective way to access high quality, nutritious animal foods. Ask your local butcher or grocery store which of their animal foods are raised in the most ethical, healthy ways. It may be helpful to know that some of the most nutritious cuts of meat are often also the least expensive: bone-in/skin-on chicken thighs, chicken wings/legs, pork butt and pork shoulder, whole chickens, liver and organ meats of all kinds, full-fat ground beef or ground pork, and dark ground turkey meat are good examples. If you live on a coast, consider highly nutritious and affordable fresh shellfish such as mussels and clams.

Don’t let the perfect be the enemy of the good. If you can’t afford or consistently access best choices, know that eating conventionally raised animal foods is still far healthier for you than eating processed and sweetened foods. Eggs, canned tuna/sardines/mackerel, rotisserie chicken, and even many simple deli meats are good options when you’re too busy to cook or on the run.

You can learn more about how to choose and support sustainable animal foods by visiting the Ethical Omnivore resources page.

Bottom line about meat and health:

• Healthy animal foods are wholesome and nutritionally complete.
• Meat is easy to digest and absorb, and contains no anti-nutrients or irritating substances.
• There is no evidence that meat, saturated fat, or cholesterol are harmful to human health. In fact, there is plenty of evidence that meat, saturated fat and cholesterol are vital to health.
• Whenever possible, choose healthy meats from naturally-raised animals.
• Limit processed meats.
• When eating grilled meats, you may want to trim away any burned or blackened edges.

Meat has a bad reputation. Most people think of meat, especially red meat, as dangerously unhealthy. However, meat has unique properties that make it more nutritious, easier to digest, and less likely to irritate your body than vegetables. Does the science behind meat-phobia hold up under the microscope?

Is red meat less healthy than other kinds of meat?

Meat is made of animal muscle fibers, which come in two major types: fast and slow. Dark muscle fibers (“slow” fibers) are designed for endurance activities, whereas light muscle fibers (“quick” fibers) are designed for rapid bursts of activity and tire easily. Therefore, dark muscle fibers have greater energy needs. For muscles to make energy, they need an energy source (fat), oxygen to burn the fat, and vitamins and minerals to run the reactions that release the energy from the fat. Therefore, dark meats usually contain more more fat, vitamins and minerals than light/white meats.

To hold the oxygen, dark (slow) muscle fibers need larger amounts of an oxygen carrier protein called myoglobin. Myoglobin is red, which is why red meat is red. Myoglobin is rich in iron, the mineral that binds oxygen, so red meats contain more iron than white meats. Because most dark meats contain more fat than light meats, they can be higher in calories. However, because dark meats also contain more minerals and B vitamins, they are actually more nutritious than light meats.

Did you know that all types of meat—red, light, and white—whether from mammals, birds, or fish—contain about the same amount of cholesterol? There is no more cholesterol in a pound of steak than in a pound of chicken.

But doesn’t red meat increase risk of death?

A study conducted at the Harvard School of Public Health [Pan 2012] claimed that eating red meat increases our risk of death from all kinds of diseases, including heart disease and cancer. This was an epidemiological study, which, by its very nature, is incapable of proving cause and effect; therefore, even if it were the best epidemiological study ever done on the planet, it would be impossible for the authors to conclude that red meat causes death.

Below are just two of the problems I noticed in this study:

1. There were two huge groups of people in this study: the Nurses’ Health Study (over 120,000 women) and the Health Professionals Follow-up study (over 50,000 men). Every 2 years, the nurses were asked how often they had eaten red meat over the past 2 years. Every 4 years, the male health professionals were asked how often they had eaten red meat over the previous 12 months. Can you imagine? Even though I keep track of what I eat in a daily food record, if you asked me what I ate LAST WEEK (never mind 1 to 2 years ago), I honestly couldn’t tell you. Naturally, these questionnaires can’t tell us how often people forget, underestimate, or perhaps even lie about what they were actually eating.
2. It just so happened that the people who reported eating the most red meat per day, also happened to be more likely to:

• smoke cigarettes
• be sedentary
• weigh more
• have diabetes
• take aspirin
• eat more calories per day
• drink more alcohol
• eat more dairy products

These are all excellent examples of what researchers call “confounding variables.” Confounding—translation? Confusing. Even if all of the data are accurate, how can we really know whether the people who ate more red meat were more likely to die because of the red meat, or because of one or more of these other issues?

For a more detailed critique of this study, please see Gary Taubes’ excellent blogpost, entitled “Science, Pseudoscience, Nutritional Epidemiology, and Meat.”

Are saturated fat and cholesterol bad for my heart?

Numerous studies by cardiology researchers have finally disproved the myths that dietary fat, meat, and cholesterol cause heart disease. In fact, some of the healthiest diets in human history have been very high in meat and animal fat. To read more about this topic, please see my post “The History of All-Meat Diets.” We have been eating animal meats, animal fat, and cholesterol for about two million years, but heart disease has only been a major problem for us for about 50 years. The major culprit is therefore much more likely to be something that is NEW in our diets; the current evidence points most strongly to refined and high glycemic index carbohydrates, not fat, meat, or cholesterol. To read more about how sugar raises “bad” cholesterol levels and why dietary cholesterol is not bad for you, please see my cholesterol page. To read more about the connection between sugar, insulin resistance, and heart disease, please see my post “Why Sugar is Bad For You: A Summary of the Research.” To see an example of how researchers desperately twist logic in an effort to connect red meat to heart disease, please see my post “Does Carnitine From Red Meat Cause Heart Disease?“

Does red meat cause cancer?

If meat is so carcinogenic, why was cancer so uncommon until the last century or so? We are not eating any more meat now than we did a hundred years ago, yet cancer incidence is skyrocketing. So, why do we believe that meat causes cancer?

There have been numerous research studies claiming to tie red meat to cancer (particularly colon cancer), however, these were weak epidemiological studies, and are not representative of results in the field as a whole. The fact is that studies of meat and cancer yield very mixed results. Many studies show no connection at all between meat and cancer, and some studies even show a protective benefit. There is simply no solid scientific evidence to support the belief that red meat increases cancer risk.

This did not stop the World Health Organization (WHO) from proclaiming to the planet in October 2015 that red and processed meats cause cancer. Unfortunately, the WHO report is all smoke and mirrors. To see what I mean, please read my detailed analysis of the WHO report: “WHO Says Meat Causes Cancer?“

Charred meats and cancer

Charred meats and wood-smoked meats contain “PAHs” (polycyclic aromatic hydrocarbons) and “HCAs” (heterocyclic amines). PAHs and HCAs have been shown to cause cancer in lab animals. Studies in humans are limited to epidemiological studies, and even these have been inconclusive.

PAHs are present not just in charred meats, but also in anything organic (plant/animal matter) that has been burned–from cigarettes to forest fire smoke to automobile exhaust. PAHs are also present in many other foods, such as cereals, vegetable oils, cheese, and coffee. In fact, cereal products, not meats, are the biggest sources of PAHs in the typical diet.

HCAs, on the other hand, can only be formed from protein-rich foods, such as meat, fish, and poultry.

Grilled and fried chicken can contain even higher amounts of PAHs and HCAs than grilled red meats, yet studies have shown no connection between poultry intake and cancer.

Nitrates and nitrites in processed meats

Nitrates and nitrites are used in the production of processed meats like bacon, salami, and ham. However, they are also found naturally in many plant foods, often in very high amounts. For example, pound for pound, spinach contains at least 30 times more of these compounds than hot dogs do (see table to the left1). In fact, some manufacturers of processed meats boast that they use celery powder (very high in nitrate), instead of the more commonly used sodium nitrite to preserve their meats.

What is the difference between nitrates and nitrites? It can be confusing because these terms are often used interchangeably by food manufacturers, physicians, and nutritionists. The reason why people lump them together so often is because nitrates easily turn into nitrites in foods and in the body. Nitrates and nitrites are very similar chemical salts with very similar properties, and mixtures of nitrates and nitrites are often used in food processing. Nitrites are about three times more potent than nitrates as preservatives.

In combination with salt, nitrates and nitrites prevent the growth of the bacteria that causes botulism (a type of food poisoning). They also act as antioxidants, keeping the fat in the meat from turning rancid, and giving the meat an unnatural pink color. Nitrates and nitrites themselves have not been shown to cause cancer; however, they can react with proteins in the meat to form nitrosamines, which are known to cause cancer in laboratory animals. The addition of special antioxidants during processing cuts down on this chemical reaction and reduces the amount of nitrosamine formed, but doesn’t eliminate it completely. Therefore it is best to choose fresh, unprocessed meats when possible.

It may also be wise to limit intake of vegetables that are very high in nitrates, such as spinach and celery. Bacteria in our saliva convert vegetable nitrates into nitrites, which we swallow. These nitrites can then react with proteins in our stomach to form nitrosamines, exactly the same way they do during meat processing. These nitrosamines are potential carcinogens; this is why some researchers believe that diets high in nitrates are associated with increasing rates of stomach cancer.

Will animal protein damage my kidneys?

To the best of my knowledge, there’s no clinical trial evidence for it so far. The human kidney is designed to be able to handle large quantities of animal protein, perhaps because our ancestors would have sometimes needed to eat large amounts of meat at one sitting, instead of eating smaller portions several times per day every day, the way we modern people do.

The vast majority of studies suggesting a connection between high protein intake and kidney damage have been conducted on laboratory animals or have been epidemiological studies. A 2011 review of the research [Odermatt] examining the connection between diet and kidney disease cited only a single human clinical trial designed to explore this question, and the results were very reassuring:

“Serum creatinine levels and estimated glomerular filtration rate did not change in individuals with normal renal function after 1 yr of a low-carbohydrate diet with higher protein (35% kcal from protein compared with 24%) and fat intake (61% compared with 30%).”

A study done in 1930 of two men who ate a 100% meat diet for a full year revealed no signs of kidney problems whatsoever. [McLellan]

Meat is the only nutritionally complete food

Animal foods (particularly when organ meats are included) contain all of the protein, fat, vitamins and minerals that humans need to function. They contain absolutely everything we need in just the right proportions. That makes sense, because for most of human history, these would have been the only foods available just about everywhere on the planet in all seasons.

Below you can see that animal products are superior sources of most essential vitamins and minerals, including 4 that do not exist in plant foods at all:

Meat nutrients are ready-to-use.

In contrast to vegetables, meat does not contain any “anti-nutrients”, like cellulose, phytates and tannins that interfere with digestion or absorption of vital compounds such as vitamins and minerals.

The forms of vitamins and minerals in meat are the easiest forms to absorb:

• “Heme” iron, the form of iron found in meat, is at least 3 times more available to our bodies than “non-heme” (vegetable) iron.
• Vitamin A from animal sources is 12 to 24 times more available to us than vegetarian sources.
• Vitamins B12 and K2 are only found in animal foods.

Meat is naturally low in carbohydrate

This means that it is impossible to eat meat and generate a significant insulin spike. Insulin spikes are to be avoided as much as possible, as they seriously destabilize our brain and body chemistry and can lead to inflammation, cell damage, disruption of cholesterol and fat metabolism, and numerous chronic diseases.

Meat is gentle on your delicate system.

While vegetables protect themselves with chemicals that are potentially harmful to our cells, animals protect their meat with claws and fangs, so meat itself does not contain any irritating substances. Meat is an especially friendly choice if you tend to be chemically sensitive.

Is meat hard to digest?

Quite the opposite. Meat is efficiently broken down by our own natural enzymes, so we do not need to rely on intestinal bacteria to help us digest it. This means that there are virtually no intestinal gases produced in the process. Meat is efficiently absorbed by our intestines, so there is very little wasted. The belief that meat contributes to constipation is a myth. Unless you have a specific sensitivity to a certain type of meat, you will have no trouble digesting it. Meat can, however, become “trapped” in your digestive tract behind sluggish high-fiber plant foods and dairy products, which are very difficult to digest.

What about meat and gout?

Please see my blog article: “Got Gout but Love Meat?“

Can eating meat cause iron overload?

I find no evidence in the scientific or medical literature linking meat consumption to iron overload. It is true that too much iron can be toxic to cells, and it is true that the body has no way to get rid of excess iron other than through the shedding of skin and intestinal cells or through bleeding. However, the body is very smart and knows not to absorb too much iron. The liver releases a hormone called hepcidin which monitors our iron status and tells our intestinal cells exactly how much iron to absorb. On average, we lose 1 to 3 mg of iron per day, so this is approximately how much we absorb.

Every article I found about iron overload in humans, including an excellent 2012 review in the New England Journal of Medicine, had to do with health conditions that disrupt normal iron metabolism, not with simple overindulgence in red meat. These include hemochromatosis and other genetic disorders of iron metabolism, certain enzyme deficiency disorders, liver disease (alcohol-induced liver damage, viral hepatitis), multiple blood transfusions, and iron supplement overdose (as opposed to red meat overdose). There is also a common non-genetic health problem that can disrupt normal iron processing in the liver called “dysmetabolic hyperferritinemia.” DH is seen in some individuals who have severe metabolic syndrome, usually with fatty liver. While iron deficiency is a very common diet-related condition, diet-induced iron overload does not seem to exist in otherwise healthy people.

What types of meat are healthiest to eat?

Healthy, naturally-raised animals fed their natural diets produce meats with healthier fat profiles, including higher levels of essential omega-3 fatty acids than grain-fed animals.

Avoid factory-farmed, grain-fed animals when you can. Whenever possible and affordable, choose meat products from naturally-raised animals. This means animals that have been fed a diet most similar to what they would eat if they were living in the wild:

• Cows/Lambs/Sheep—grasses
• Chickens—grasses, insects, worms
• Turkeys—grasses, insects, seeds, small animals
• Ducks/geese—fish, grass, algae, insects, fruits
• Pigs— grasses, root vegetables, fruits, nuts, insects, worms, small animals
• Fish—wild, not farmed. Food varies depending on species.

Poultry sellers often boast that their birds are fed an all-vegetarian diet, but if you notice above, birds are naturally omnivores and eat small creatures for protein and fat (worms and insects, for example). This is why backyard birds enjoy suet (animal fat) in the wintertime—insects and worms are scarce in winter and they need the fat and protein for energy.

Does Meat Quality Matter?

It is best for human health, environmental health and animal health and welfare reasons to choose meats raised humanely and sustainably from healthy animals being fed a species-appropriate diet: pasture-raised land animals, wild-caught seafood and wild game. However, not everyone can afford or consistently access animal foods that meet all of these criteria.

Purchasing meat, poultry, and eggs from local community supported agriculture organizations or from responsible online seafood, poultry and red meat distributors can be a reasonably cost-effective way to access high quality, nutritious animal foods. Ask your local butcher or grocery store which of their animal foods are raised in the most ethical, healthy ways. It may be helpful to know that some of the most nutritious cuts of meat are often also the least expensive: bone-in/skin-on chicken thighs, chicken wings/legs, pork butt and pork shoulder, whole chickens, liver and organ meats of all kinds, full-fat ground beef or ground pork, and dark ground turkey meat are good examples. If you live on a coast, consider highly nutritious and affordable fresh shellfish such as mussels and clams.

Don’t let the perfect be the enemy of the good. If you can’t afford or consistently access best choices, know that eating conventionally raised animal foods is still far healthier for you than eating processed and sweetened foods. Eggs, canned tuna/sardines/mackerel, rotisserie chicken, and even many simple deli meats are good options when you’re too busy to cook or on the run.

You can learn more about how to choose and support sustainable animal foods by visiting the Ethical Omnivore resources page.

Bottom line about meat and health:

• Healthy animal foods are wholesome and nutritionally complete.
• Meat is easy to digest and absorb, and contains no anti-nutrients or irritating substances.
• There is no evidence that meat, saturated fat, or cholesterol are harmful to human health. In fact, there is plenty of evidence that meat, saturated fat and cholesterol are vital to health.
• Whenever possible, choose healthy meats from naturally-raised animals.
• Limit processed meats.
• When eating grilled meats, you may want to trim away any burned or blackened edges.

Poor cholesterol—so misunderstood. All animal cells require cholesterol for proper structure and function. The vast majority of cholesterol in the body does not come directly from foods like eggs and meat, but from the liver, which can make cholesterol out of anything we eat. So, if cholesterol-rich foods don’t cause high cholesterol, what does?

What is cholesterol?

Most people have no idea what cholesterol actually is.

Life without cholesterol would be impossible. Cell membranes, which wrap around and protect the inner contents of all cells, must contain cholesterol in order to function properly. Cholesterol contributes firmness to membranes and keeps them from falling apart. But wait, there’s more!

All of the following critical body components are made from cholesterol:

• Estrogen
• Testosterone
• Progesterone
• Cortisol (anti-inflammatory stress hormone)
• Aldosterone (regulates salt balance)
• Vitamin D
• Bile (required for fat and vitamin absorption)
• Brain synapses (neurotransmitter exchange)
• Myelin sheath (insulates nerve cells)

What is the difference between fat and cholesterol?

Cholesterol is made of carbon, hydrogen, and oxygen, just like fat is, but it is not fatty; it is a hard, waxy substance that contains no fat. A molecule of fat looks like this:

whereas a molecule of cholesterol looks like this:

As you may be able to appreciate just by looking at them, they are very different from each other.

Fat is a simple long chain, whereas cholesterol is mainly a complicated combination of rings—3 hexagons plus a pentagon; in medical school we affectionately called it “three rooms and a bath.” Fat is relatively easy to build (11 chemical steps from acetyl-coA to triacylglycerol), whereas cholesterol is hard to construct—more than 30 chemical steps are required to build one molecule of cholesterol (from acetyl-coA to cholesterol). The body would not go to the trouble of making it for no reason. Especially since, as it turns out, once it’s built, it’s impossible for the body to break it down—we do not have any way to take apart its complex ringed structure.

Cholesterol in foods

How much cholesterol do we need to eat?

None. Cholesterol is so important that the body can make cholesterol out of anything—fats, carbohydrates, or proteins. You don’t have to eat cholesterol to make cholesterol. Even if you eat a completely cholesterol-free diet, as vegans do, your body will still make cholesterol. Type “vegans with high cholesterol” into your search engine and you will find plenty of accounts of vegans whose cholesterol is too high—despite the fact that they eat ZERO grams of cholesterol.

Which foods contain cholesterol?

Since every single animal cell contains cholesterol, all animal foods contain cholesterol.

Many people don’t realize that all muscle meats (chicken, fish, beef, pork, etc.) contain about the same amount of cholesterol per serving.

Certain animal foods—liver, egg yolk, dairy fats, glandular organ meats, and brain— are especially high in cholesterol. Why is that? Liver is where the body manufactures cholesterol. Egg yolks contain concentrated cholesterol because the growing baby chick needs it to build new cells. Milk fat contains lots of cholesterol because the growing baby calf needs it to build new cells. Glandular organ meats (pancreas, kidney, etc.) contain more cholesterol because glands make hormones, and hormones are made from cholesterol. Brain contains very high amounts of cholesterol in its myelin sheaths, which insulate its electrical circuits.

All plant foods are considered “cholesterol-free.” Well, it would be more accurate to say that plant foods do not contain any animal cholesterol. Plants contain their own special forms of cholesterol called “phytosterols”, but phytosterols are toxic to human cells, so our intestines wisely refuse to absorb them.

So, in most cases, animal foods contain some cholesterol that the body can absorb and use, and all plant foods contain cholesterol that our body cannot absorb. The only exceptions I know of to these rules are shellfish.

There are two types of shellfish: crustaceans (lobsters, shrimp, crabs, etc.) and mollusks (clams, oysters, mussels, etc.). Crustaceans—giant sea insects who hunt for their food—contain animal cholesterols that can be absorbed by the body, but mollusks—who gather nutrients by filtering seawater—contain a different type of cholesterol that we can’t absorb.

In fact, plant cholesterols and mollusk cholesterols are not only rejected by our intestinal cells, they actually interfere with the absorption of animal cholesterols. This is how margarines such as Benecol® work. The manufacturer has added a chemically altered form of plant cholesterol to the spread, which interferes with the absorption of animal cholesterol.

Will eating cholesterol raise my cholesterol?

Yes, but only if your body needs more cholesterol.

The cells lining the small intestine each contain transporter molecules (NPC1L1) that absorb cholesterol. [The cholesterol-lowering drug Zetia® works by blocking NPC1L1 yet does not reduce risk of heart disease]. However, if the body doesn’t need any more cholesterol, there are other molecules (ABCG5/8 transporters) that pump the cholesterol right back out into the intestines to be eliminated from the body. This is one reason why it is virtually impossible for cholesterol from food to cause “high cholesterol.” The intestinal cells know exactly how much is needed and will not allow extra to be absorbed.

This is brilliant when you think about it (the body is so smart)—it is impossible for the body to break down the complex structure of the cholesterol molecule, so it would make no sense to absorb too much—once it’s inside the body there’s only one way to get rid of it, and that is to excrete it in the bile. Why take in more than necessary, if it’s just going to have to be eliminated?

However, if your body cholesterol levels are low, the intestinal cells will not kick it out, and it will make it into your bloodstream—because you need it.

What’s more, cholesterol is recycled very efficiently by our bodies, because it is so hard to make. Why make more from scratch if you don’t have to? Remember that it’s also impossible for the body to break down cholesterol, so the only way to get rid of it is to excrete it. The liver gets rid of any excess by excreting free cholesterol into the intestines along with bile. This free form of cholesterol is the only form that intestinal cells are able to absorb. Most of the cholesterol molecules in food (85 to 90% of them) are not free; they are in the form of “cholesterol esters.” [Cholesterol esters are just cholesterol molecules with a fatty acid attached]. Intestinal cells are incapable of absorbing cholesterol ester, which is the major form of cholesterol in food. Therefore, if the intestinal cells sense that the body needs more cholesterol, it will typically reabsorb most of what the body needs from the bile, not from food.

To summarize the relationship between food cholesterol and blood cholesterol:

1. Most cholesterol from food does not get absorbed unless body levels are low.
2. The amount of cholesterol you eat has almost no effect on your cholesterol levels.
3. The vast majority of cholesterol in your body is made by your body’s own cells. Remember that creepy line from the movie When a Stranger Calls? “The call is coming from inside the house.” The excess cholesterol is coming from inside your body, not from the food you eat.

How does the body make cholesterol?

All cells can make their own cholesterol, but liver cells are especially good at it. Only liver cells are capable of making more than they need for themselves—and shipping it out to other parts of the body.

Remember how it takes more than 30 chemical reactions to build one molecule of cholesterol? The most important of all of these steps is step #3. In this step, a critical enzyme called “HMG-CoA reductase” converts a molecule called HMG-CoA into another molecule called mevalonate. Once this step occurs, there’s no turning back, so it’s a big commitment. This reaction is the one that determines whether or not cholesterol gets made. Therefore, the enzyme that runs this reaction, HMG-CoA reductase, is very important—it’s like the foreman in charge of the cholesterol assembly line. This enzyme needs to be carefully controlled, because we don’t want cells wasting their time and energy building expensive cholesterol molecules willy-nilly.

The activity of this critical enzyme HMG-CoA reductase is controlled primarily by two things:

1. cholesterol levels inside the cell
2. insulin levels in the blood.

This is where things get really interesting. It makes sense that HMG-CoA reductase would respond to the cell’s cholesterol levels—if the cell’s levels are low, you want to turn that enzyme on, so you can make more cholesterol, and if the cell has enough cholesterol, you want to turn that enzyme off and stop making cholesterol. But what is insulin doing in the mix?

We think of insulin as a blood sugar regulator, but its real job is to be a growth hormone. Insulin is supposed to turn on when we need to grow. What do we need to make in order to grow? More cells. What do we need to form new cells? Cholesterol. So, at times when we need to grow (babies, teenagers, pregnant women), insulin turns the enzyme HMG-CoA reductase ON, which tells cells to make more cholesterol, so we can build new cells.

What causes high cholesterol?

Why would the body make more cholesterol than it needs?

Now here’s the problem: when people eat too many sugars and starches, especially refined and high glycemic index foods, blood insulin levels can spike. When insulin spikes, it turns on HMG–CoA reductase, which tells all of the body’s cells to make more cholesterol, even if they don’t need any more. This is probably the most important reason why some people have too much cholesterol in their bloodstream. Sugars and starches can raise insulin levels, which fools the body into thinking it should grow when it doesn’t need to. This is how low glycemic index diets and low-carbohydrate diets normalize cholesterol patterns—these diets reduce insulin levels, which in turn lower HMG-CoA reductase activity.

“Statin” drugs, such as Lipitor®, which are prescribed to lower cholesterol levels, work partly by interfering with the activity of HMG-CoA reductase. If your cells happen to need more cholesterol under certain circumstances, but the statin drug is blocking this critical enzyme, your cells may not be able to make cholesterol when needed. And what’s worse is that the cholesterol synthesis pathway doesn’t just make cholesterol; branches of this same pathway are responsible for synthesizing a wide variety of other important molecules, including: Vitamin A, Vitamin E, Vitamin K, and Coenzyme Q. So, you may want to think twice before you artificially interfere with this pathway by taking a statin drug.

When you eat less carbohydrate, you are not artificially blocking the pathway; you are simply allowing HMG-CoA reductase to listen to other more important signals (such as cholesterol levels and growth requirements) and decide naturally when it should turn on and when it should turn off.

So, to recap: refined carbohydrates speed up the cholesterol assembly line and statins slow it down. Which approach would you rather take to manage your “cholesterol problem”—taking a drug that artificially slows down this assembly line, or changing your diet so that the assembly line only runs when it’s supposed to? [Hint: Dietary changes require no monthly co-pays, and have no potentially dangerous side effects. I write about the dangerous brain side effects of statins in my Psychology Today post: “Low Brain Cholesterol—Separating Fact from Fiction.”]

Chances are: if you have “high cholesterol” you do not have a cholesterol problem—you have a carbohydrate problem.

Good cholesterol and bad cholesterol

This gets into the very complicated relationship between cholesterol blood tests and heart disease risk. This is an enormous topic, but I’ll summarize some basic points.

When you get your cholesterol levels checked, you will see numbers for HDL and LDL, as well as triglycerides. Triglycerides are fats, so we’ll set them aside and just focus on HDL and LDL.

HDL particles collect extra cholesterol from around the body and carry it back to the liver to be eliminated from the body if we don’t need it. It is typically thought of as “good cholesterol” so higher HDL levels are considered a good sign.

LDL particles carry extra cholesterol made in the liver out to the rest of the cells in the body. We used to think of LDL as “bad cholesterol” so lower levels of LDL were considered a good sign.

The cholesterol inside of HDL and LDL particles is exactly the same, it’s just that, for the most part, HDL is carrying it in one direction and LDL is carrying it in the opposite direction. The reason why LDL had been dubbed “bad” and HDL has been dubbed “good” is that numerous epidemiological studies (most famously, the Framingham Heart Study) told us that high LDL levels were associated with a higher risk of heart attack, and that high HDL levels were associated with a lower risk of heart attack.

We used to think that HDL was good because it acted like a garbage truck, clearing evil cholesterol out of our bodies, and we used to think that LDL was bad because it burrowed its way into our coronary arteries, depositing evil cholesterol there—forming plaques and causing heart attacks.

Cholesterol, carbohydrates and heart disease

However, this simplistic way of thinking about cholesterol and heart disease is changing before our very eyes. It turns out that it is more complicated than this. LDL, for example, exists in a variety of forms. It can be big and buoyant and “fluffy” or small and dense and oxidized (damaged). The new thinking is that small, dense, oxidized LDL may be the only type of LDL that is associated with heart disease. Therefore, instead of thinking of all LDL as “bad”, it would be more accurate to say that all LDL is not created equal—big fluffy LDL is “good” and small, dense, oxidized LDL is “bad.”

Unfortunately, standard blood tests can’t tell you which type of LDL you have because it lumps all types of LDL particles together. Standard tests can only estimate how much of your cholesterol is travelling inside of LDL particles. They can’t tell you how many LDL particles you have, how big they are, how dense they are, or how oxidized they are. [For a detailed explanation of the complexities involved in interpreting cholesterol blood test results, I recommend Dr. Peter Attia’s blog at www.eatingacademy.com.]

What we do know from research studies is that people who eat a diet high in refined carbohydrates tend to have a higher number of “bad” (smaller, denser, oxidized) LDL particles. This makes sense, because we know that carbohydrates are “pro-oxidants”—meaning they can cause oxidation.

There is also lots of evidence telling us that refined carbohydrates can cause inflammation. Just because doctors find cholesterol inside artery-clogging plaques does not mean that cholesterol causes plaques. It is now well established that heart disease is a disease of inflammation. It is not simply that an innocent, smooth, buoyant sphere of fat and cholesterol traveling through the bloodstream decides to somehow randomly dig its way into a healthy coronary artery. The first step in the development of a vessel-clogging plaque is inflammation within the lining of the artery itself. When doctors cut into plaques they don’t just find cholesterol—they find many signs of inflammation (such as macrophages, calcium, and T cells). Wherever there is inflammation in the body, cholesterol is rushed to the scene to repair the damage—because we need cholesterol to build healthy new cells. Jumping to the conclusion that coronary artery plaques are caused by the cholesterol found inside of them is like assuming that all car accidents are caused by the ambulances that are found on the scene.

The latest research suggests that diets high in refined and high glycemic index carbohydrates increase the risk of inflammation throughout the body, especially in blood vessels. Diabetes, a disease which is intimately associated with high blood sugar levels, is infamous for causing damage to blood vessels in the retina, kidneys, and tiny vessels that feed nerve endings in the feet. It is well established that people with diabetes are also at higher risk for heart disease. It should therefore not be a stretch for us to imagine that all people with high blood sugar and/or insulin levels due to diets rich in refined carbohydrates may also be at increased risk for cardiovascular disease.

Cardiology researchers are now turning away from the notion that saturated fat and cholesterol cause heart disease. After all, how could saturated fat and cholesterol, which we have been eating for hundreds of thousands of years, be at the root of heart disease, which is a relatively new phenomenon? Cardiologists are finding instead that refined carbohydrate (such as sugar and flour), which we have only been eating in significant quantities for about a hundred years, is the single most important dietary risk factor for heart attacks:

“Strong evidence supports . . . associations of harmful factors, including intake of trans-fatty acids and foods with a high glycemic index or load.”

“Insufficient evidence of association is present for intake of . . . saturated and polyunsaturated fatty acids; total fat, . . . meat, eggs, and milk.” [Mente 2009].

Sweetheart?

There are several plausible mechanisms for how refined carbohydrate could increase risk for heart disease and change cholesterol profiles:

• Diets high in refined carbohydrate lower HDL levels and set the stage for high insulin levels, oxidation, and inflammation throughout the body, including in the coronary arteries.
• High blood sugar and insulin levels turn big, fluffy, innocent LDL particles into small, dense, oxidized LDL particles, which are associated with increased risk for heart disease.
• High insulin levels turn on the cholesterol building enzyme HMG-CoA reductase, forcing the body to make more cholesterol than it needs.

It is becoming increasingly obvious that cholesterol is innocent until corrupted by refined carbohydrate.

Poor cholesterol—so misunderstood. All animal cells require cholesterol for proper structure and function. The vast majority of cholesterol in the body does not come directly from foods like eggs and meat, but from the liver, which can make cholesterol out of anything we eat. So, if cholesterol-rich foods don’t cause high cholesterol, what does?

What is cholesterol?

Most people have no idea what cholesterol actually is.

Life without cholesterol would be impossible. Cell membranes, which wrap around and protect the inner contents of all cells, must contain cholesterol in order to function properly. Cholesterol contributes firmness to membranes and keeps them from falling apart. But wait, there’s more!

All of the following critical body components are made from cholesterol:

• Estrogen
• Testosterone
• Progesterone
• Cortisol (anti-inflammatory stress hormone)
• Aldosterone (regulates salt balance)
• Vitamin D
• Bile (required for fat and vitamin absorption)
• Brain synapses (neurotransmitter exchange)
• Myelin sheath (insulates nerve cells)

What is the difference between fat and cholesterol?

Cholesterol is made of carbon, hydrogen, and oxygen, just like fat is, but it is not fatty; it is a hard, waxy substance that contains no fat. A molecule of fat looks like this:

whereas a molecule of cholesterol looks like this:

As you may be able to appreciate just by looking at them, they are very different from each other.

Fat is a simple long chain, whereas cholesterol is mainly a complicated combination of rings—3 hexagons plus a pentagon; in medical school we affectionately called it “three rooms and a bath.” Fat is relatively easy to build (11 chemical steps from acetyl-coA to triacylglycerol), whereas cholesterol is hard to construct—more than 30 chemical steps are required to build one molecule of cholesterol (from acetyl-coA to cholesterol). The body would not go to the trouble of making it for no reason. Especially since, as it turns out, once it’s built, it’s impossible for the body to break it down—we do not have any way to take apart its complex ringed structure.

Cholesterol in foods

How much cholesterol do we need to eat?

None. Cholesterol is so important that the body can make cholesterol out of anything—fats, carbohydrates, or proteins. You don’t have to eat cholesterol to make cholesterol. Even if you eat a completely cholesterol-free diet, as vegans do, your body will still make cholesterol. Type “vegans with high cholesterol” into your search engine and you will find plenty of accounts of vegans whose cholesterol is too high—despite the fact that they eat ZERO grams of cholesterol.

Which foods contain cholesterol?

Since every single animal cell contains cholesterol, all animal foods contain cholesterol.

Many people don’t realize that all muscle meats (chicken, fish, beef, pork, etc.) contain about the same amount of cholesterol per serving.

Certain animal foods—liver, egg yolk, dairy fats, glandular organ meats, and brain— are especially high in cholesterol. Why is that? Liver is where the body manufactures cholesterol. Egg yolks contain concentrated cholesterol because the growing baby chick needs it to build new cells. Milk fat contains lots of cholesterol because the growing baby calf needs it to build new cells. Glandular organ meats (pancreas, kidney, etc.) contain more cholesterol because glands make hormones, and hormones are made from cholesterol. Brain contains very high amounts of cholesterol in its myelin sheaths, which insulate its electrical circuits.

All plant foods are considered “cholesterol-free.” Well, it would be more accurate to say that plant foods do not contain any animal cholesterol. Plants contain their own special forms of cholesterol called “phytosterols”, but phytosterols are toxic to human cells, so our intestines wisely refuse to absorb them.

So, in most cases, animal foods contain some cholesterol that the body can absorb and use, and all plant foods contain cholesterol that our body cannot absorb. The only exceptions I know of to these rules are shellfish.

There are two types of shellfish: crustaceans (lobsters, shrimp, crabs, etc.) and mollusks (clams, oysters, mussels, etc.). Crustaceans—giant sea insects who hunt for their food—contain animal cholesterols that can be absorbed by the body, but mollusks—who gather nutrients by filtering seawater—contain a different type of cholesterol that we can’t absorb.

In fact, plant cholesterols and mollusk cholesterols are not only rejected by our intestinal cells, they actually interfere with the absorption of animal cholesterols. This is how margarines such as Benecol® work. The manufacturer has added a chemically altered form of plant cholesterol to the spread, which interferes with the absorption of animal cholesterol.

Will eating cholesterol raise my cholesterol?

Yes, but only if your body needs more cholesterol.

The cells lining the small intestine each contain transporter molecules (NPC1L1) that absorb cholesterol. [The cholesterol-lowering drug Zetia® works by blocking NPC1L1 yet does not reduce risk of heart disease]. However, if the body doesn’t need any more cholesterol, there are other molecules (ABCG5/8 transporters) that pump the cholesterol right back out into the intestines to be eliminated from the body. This is one reason why it is virtually impossible for cholesterol from food to cause “high cholesterol.” The intestinal cells know exactly how much is needed and will not allow extra to be absorbed.

This is brilliant when you think about it (the body is so smart)—it is impossible for the body to break down the complex structure of the cholesterol molecule, so it would make no sense to absorb too much—once it’s inside the body there’s only one way to get rid of it, and that is to excrete it in the bile. Why take in more than necessary, if it’s just going to have to be eliminated?

However, if your body cholesterol levels are low, the intestinal cells will not kick it out, and it will make it into your bloodstream—because you need it.

What’s more, cholesterol is recycled very efficiently by our bodies, because it is so hard to make. Why make more from scratch if you don’t have to? Remember that it’s also impossible for the body to break down cholesterol, so the only way to get rid of it is to excrete it. The liver gets rid of any excess by excreting free cholesterol into the intestines along with bile. This free form of cholesterol is the only form that intestinal cells are able to absorb. Most of the cholesterol molecules in food (85 to 90% of them) are not free; they are in the form of “cholesterol esters.” [Cholesterol esters are just cholesterol molecules with a fatty acid attached]. Intestinal cells are incapable of absorbing cholesterol ester, which is the major form of cholesterol in food. Therefore, if the intestinal cells sense that the body needs more cholesterol, it will typically reabsorb most of what the body needs from the bile, not from food.

To summarize the relationship between food cholesterol and blood cholesterol:

1. Most cholesterol from food does not get absorbed unless body levels are low.
2. The amount of cholesterol you eat has almost no effect on your cholesterol levels.
3. The vast majority of cholesterol in your body is made by your body’s own cells. Remember that creepy line from the movie When a Stranger Calls? “The call is coming from inside the house.” The excess cholesterol is coming from inside your body, not from the food you eat.

How does the body make cholesterol?

All cells can make their own cholesterol, but liver cells are especially good at it. Only liver cells are capable of making more than they need for themselves—and shipping it out to other parts of the body.

Remember how it takes more than 30 chemical reactions to build one molecule of cholesterol? The most important of all of these steps is step #3. In this step, a critical enzyme called “HMG-CoA reductase” converts a molecule called HMG-CoA into another molecule called mevalonate. Once this step occurs, there’s no turning back, so it’s a big commitment. This reaction is the one that determines whether or not cholesterol gets made. Therefore, the enzyme that runs this reaction, HMG-CoA reductase, is very important—it’s like the foreman in charge of the cholesterol assembly line. This enzyme needs to be carefully controlled, because we don’t want cells wasting their time and energy building expensive cholesterol molecules willy-nilly.

The activity of this critical enzyme HMG-CoA reductase is controlled primarily by two things:

1. cholesterol levels inside the cell
2. insulin levels in the blood.

This is where things get really interesting. It makes sense that HMG-CoA reductase would respond to the cell’s cholesterol levels—if the cell’s levels are low, you want to turn that enzyme on, so you can make more cholesterol, and if the cell has enough cholesterol, you want to turn that enzyme off and stop making cholesterol. But what is insulin doing in the mix?

We think of insulin as a blood sugar regulator, but its real job is to be a growth hormone. Insulin is supposed to turn on when we need to grow. What do we need to make in order to grow? More cells. What do we need to form new cells? Cholesterol. So, at times when we need to grow (babies, teenagers, pregnant women), insulin turns the enzyme HMG-CoA reductase ON, which tells cells to make more cholesterol, so we can build new cells.

What causes high cholesterol?

Why would the body make more cholesterol than it needs?

Now here’s the problem: when people eat too many sugars and starches, especially refined and high glycemic index foods, blood insulin levels can spike. When insulin spikes, it turns on HMG–CoA reductase, which tells all of the body’s cells to make more cholesterol, even if they don’t need any more. This is probably the most important reason why some people have too much cholesterol in their bloodstream. Sugars and starches can raise insulin levels, which fools the body into thinking it should grow when it doesn’t need to. This is how low glycemic index diets and low-carbohydrate diets normalize cholesterol patterns—these diets reduce insulin levels, which in turn lower HMG-CoA reductase activity.

“Statin” drugs, such as Lipitor®, which are prescribed to lower cholesterol levels, work partly by interfering with the activity of HMG-CoA reductase. If your cells happen to need more cholesterol under certain circumstances, but the statin drug is blocking this critical enzyme, your cells may not be able to make cholesterol when needed. And what’s worse is that the cholesterol synthesis pathway doesn’t just make cholesterol; branches of this same pathway are responsible for synthesizing a wide variety of other important molecules, including: Vitamin A, Vitamin E, Vitamin K, and Coenzyme Q. So, you may want to think twice before you artificially interfere with this pathway by taking a statin drug.

When you eat less carbohydrate, you are not artificially blocking the pathway; you are simply allowing HMG-CoA reductase to listen to other more important signals (such as cholesterol levels and growth requirements) and decide naturally when it should turn on and when it should turn off.

So, to recap: refined carbohydrates speed up the cholesterol assembly line and statins slow it down. Which approach would you rather take to manage your “cholesterol problem”—taking a drug that artificially slows down this assembly line, or changing your diet so that the assembly line only runs when it’s supposed to? [Hint: Dietary changes require no monthly co-pays, and have no potentially dangerous side effects. I write about the dangerous brain side effects of statins in my Psychology Today post: “Low Brain Cholesterol—Separating Fact from Fiction.”]

Chances are: if you have “high cholesterol” you do not have a cholesterol problem—you have a carbohydrate problem.

Good cholesterol and bad cholesterol

This gets into the very complicated relationship between cholesterol blood tests and heart disease risk. This is an enormous topic, but I’ll summarize some basic points.

When you get your cholesterol levels checked, you will see numbers for HDL and LDL, as well as triglycerides. Triglycerides are fats, so we’ll set them aside and just focus on HDL and LDL.

HDL particles collect extra cholesterol from around the body and carry it back to the liver to be eliminated from the body if we don’t need it. It is typically thought of as “good cholesterol” so higher HDL levels are considered a good sign.

LDL particles carry extra cholesterol made in the liver out to the rest of the cells in the body. We used to think of LDL as “bad cholesterol” so lower levels of LDL were considered a good sign.

The cholesterol inside of HDL and LDL particles is exactly the same, it’s just that, for the most part, HDL is carrying it in one direction and LDL is carrying it in the opposite direction. The reason why LDL had been dubbed “bad” and HDL has been dubbed “good” is that numerous epidemiological studies (most famously, the Framingham Heart Study) told us that high LDL levels were associated with a higher risk of heart attack, and that high HDL levels were associated with a lower risk of heart attack.

We used to think that HDL was good because it acted like a garbage truck, clearing evil cholesterol out of our bodies, and we used to think that LDL was bad because it burrowed its way into our coronary arteries, depositing evil cholesterol there—forming plaques and causing heart attacks.

Cholesterol, carbohydrates and heart disease

However, this simplistic way of thinking about cholesterol and heart disease is changing before our very eyes. It turns out that it is more complicated than this. LDL, for example, exists in a variety of forms. It can be big and buoyant and “fluffy” or small and dense and oxidized (damaged). The new thinking is that small, dense, oxidized LDL may be the only type of LDL that is associated with heart disease. Therefore, instead of thinking of all LDL as “bad”, it would be more accurate to say that all LDL is not created equal—big fluffy LDL is “good” and small, dense, oxidized LDL is “bad.”

Unfortunately, standard blood tests can’t tell you which type of LDL you have because it lumps all types of LDL particles together. Standard tests can only estimate how much of your cholesterol is travelling inside of LDL particles. They can’t tell you how many LDL particles you have, how big they are, how dense they are, or how oxidized they are. [For a detailed explanation of the complexities involved in interpreting cholesterol blood test results, I recommend Dr. Peter Attia’s blog at www.eatingacademy.com.]

What we do know from research studies is that people who eat a diet high in refined carbohydrates tend to have a higher number of “bad” (smaller, denser, oxidized) LDL particles. This makes sense, because we know that carbohydrates are “pro-oxidants”—meaning they can cause oxidation.

There is also lots of evidence telling us that refined carbohydrates can cause inflammation. Just because doctors find cholesterol inside artery-clogging plaques does not mean that cholesterol causes plaques. It is now well established that heart disease is a disease of inflammation. It is not simply that an innocent, smooth, buoyant sphere of fat and cholesterol traveling through the bloodstream decides to somehow randomly dig its way into a healthy coronary artery. The first step in the development of a vessel-clogging plaque is inflammation within the lining of the artery itself. When doctors cut into plaques they don’t just find cholesterol—they find many signs of inflammation (such as macrophages, calcium, and T cells). Wherever there is inflammation in the body, cholesterol is rushed to the scene to repair the damage—because we need cholesterol to build healthy new cells. Jumping to the conclusion that coronary artery plaques are caused by the cholesterol found inside of them is like assuming that all car accidents are caused by the ambulances that are found on the scene.

The latest research suggests that diets high in refined and high glycemic index carbohydrates increase the risk of inflammation throughout the body, especially in blood vessels. Diabetes, a disease which is intimately associated with high blood sugar levels, is infamous for causing damage to blood vessels in the retina, kidneys, and tiny vessels that feed nerve endings in the feet. It is well established that people with diabetes are also at higher risk for heart disease. It should therefore not be a stretch for us to imagine that all people with high blood sugar and/or insulin levels due to diets rich in refined carbohydrates may also be at increased risk for cardiovascular disease.

Cardiology researchers are now turning away from the notion that saturated fat and cholesterol cause heart disease. After all, how could saturated fat and cholesterol, which we have been eating for hundreds of thousands of years, be at the root of heart disease, which is a relatively new phenomenon? Cardiologists are finding instead that refined carbohydrate (such as sugar and flour), which we have only been eating in significant quantities for about a hundred years, is the single most important dietary risk factor for heart attacks:

“Strong evidence supports . . . associations of harmful factors, including intake of trans-fatty acids and foods with a high glycemic index or load.”

“Insufficient evidence of association is present for intake of . . . saturated and polyunsaturated fatty acids; total fat, . . . meat, eggs, and milk.” [Mente 2009].

Sweetheart?

There are several plausible mechanisms for how refined carbohydrate could increase risk for heart disease and change cholesterol profiles:

• Diets high in refined carbohydrate lower HDL levels and set the stage for high insulin levels, oxidation, and inflammation throughout the body, including in the coronary arteries.
• High blood sugar and insulin levels turn big, fluffy, innocent LDL particles into small, dense, oxidized LDL particles, which are associated with increased risk for heart disease.
• High insulin levels turn on the cholesterol building enzyme HMG-CoA reductase, forcing the body to make more cholesterol than it needs.

It is becoming increasingly obvious that cholesterol is innocent until corrupted by refined carbohydrate.

Controversial carbohydrates! How can some carbohydrates—fruits, sweet potatoes, whole grains, and beans— be considered “good” and other carbohydrates—flour, sugar, and corn syrup—be considered “bad?” Doesn’t our brain need daily carbohydrate for energy? If so, how do people eating low-carb diets get by?

Let’s start with the basics . . .

What are carbohydrates?

Carbohydrates are sugars and starches. They are very simple molecules made out of carbon, hydrogen, and oxygen. All plants and animals can use carbohydrates for energy (and for building body parts and body chemicals).

What is the difference between sugars and starches?

“Sugars” are by definition very small. Glucose is a single-molecule sugar, or “monosaccharide.” Sucrose (table sugar) is a “disaccharide”, made of two molecules: one molecule of glucose plus one molecule of fructose (fruit sugar) linked together. Lactose (milk sugar) is also a disaccharide, made of one molecule of glucose plus one molecule of galactose linked together. These small sugars are sometimes referred to as “simple sugars.” Fruits are high in simple sugars.

“Starches” are big—they are made up of lots of simple sugars stuck together. Potato starch and corn starch are good examples. Starches are often referred to as “complex carbohydrates.” Most people are aware that grains, beans, nuts, seeds, and root vegetables are high in starches. However, animals also contain a small amount of starch that most people are less familiar with, called glycogen. This is a special starch designed especially for animals; plants do not contain any glycogen.

Storing sugar as starch

Humans store glycogen as an emergency source of carbohydrate. Glycogen is made of lots of glucose molecules linked together in short branches. If your blood sugar drops, or if you’re in an emergency situation and need fast energy, glycogen from the liver can be rapidly broken down into glucose and released immediately into the bloodstream.

The liver can only store somewhere between 250 and 400 calories worth of glycogen. (Glycogen is also stored in the muscles, but this glycogen is reserved exclusively for the muscles to use while exercising; it cannot be used to maintain blood sugar levels.) So, what does your liver do to make blood sugar if it runs out of glycogen between meals? It will turn to the protein in your muscles. The liver can turn muscle protein into glucose via a process called gluconeogenesis, which essentially means “making glucose from scratch.”

Why we store energy as fat

Starches are very dense and heavy. This is why we don’t store very much energy as glycogen—it would take up too much room and weigh too much. We store less than a day’s worth of energy as glycogen; the rest we store as fat.

Plants store their energy as starch, in thick, heavy roots and tubers and bulbs. That’s ok for them, because they don’t have to move, but imagine if we had to store all of our energy as starch—we’d have to carry around enormous lumps of carbohydrate—like gigantic potatoes growing underneath our skin—everywhere we went. And, if we overate and gained weight, the lumps would get so big and heavy that it would be impossible for us to move.

This is why animals like us, who need to move around, store energy as fat. Fat is much lighter and it is flexible, so it moves with us (ever try to bend a potato?). Plus, we can store lots and lots of it. There is a very low limit to the amount of glycogen we can store, but the amount of fat we can store is practically unlimited. (Just another clue that humans are designed to burn fat, not carbohydrate . . .)

Blood sugar regulation

All animals, including humans, have a simple sugar in their blood called glucose, which is also known as “blood sugar.” Glucose is used for fast energy by our cells. Because glucose is a monosaccharide (it exists as single molecules), it doesn’t have to be broken down—it is ready to burn.

It is critical that our blood sugar be kept in a very tight range for us to feel well and function properly. If blood sugar goes too high, we feel logey and foggy. Over long periods of time, high blood sugar (such as in untreated type 2 diabetes) can cause a variety of serious chronic health problems. However, if blood sugar drops too low, we are in immediate danger of serious consequences, such as seizure, coma, and death, because under normal circumstances, the brain requires some glucose to function.

Because tight blood sugar control is so important, we have a very sophisticated system for regulating it. If you eat a low-carbohydrate diet, your blood sugar levels tend to stay fairly even, but if you are like most people and eat carbohydrate throughout the day, your blood sugar will rise after you eat. It will rise even faster and higher if you eat refined or high glycemic index carbohydrates, such as sugar, flour, or fruit juice, because these types of carbohydrates are digested and absorbed very rapidly. How does the body manage these blood sugar surges?

How carbohydrates can make us fat

Let’s say you eat a popsicle. The simple sugars in the sweet popsicle are rapidly absorbed into your bloodstream, and your blood sugar quickly starts to rise. Since the body wants to harness that energy and prevent high blood sugar, your pancreas releases the hormone insulin into your bloodstream. Insulin lowers your blood sugar putting the body into sugar-burning, fat-storing mode. It literally turns off your body’s ability to burn fat so that excess sugar will be burned instead of fat. If your body has enough energy already and your cells don’t need to burn any more sugar, insulin tells the liver to turn the extra sugar into fat (lipogenesis), and then squirrels that fat away in your fat cells. That’s how sugar can make you fat.

Now, if you are not particularly carbohydrate sensitive, that may be the end of the story. You ate the popsicle, your blood sugar rose briefly, but insulin quickly took care of it, and now you’re fine. But what if you are carbohydrate sensitive? [To find out how carbohydrate-sensitive you are, take my free carbohydrate sensitivity quiz.]

Hypoglycemia and the invisible hormonal roller coaster

If you are carbohydrate sensitive (or have insulin resistance), you may have an exaggerated response to eating that popsicle. Not only does this mean that your blood sugar will rise more than usual, and stay higher for longer, it also means that your insulin level will rise more than usual, and stay higher for longer, causing your blood sugar to then drop too low or too fast. The body perceives this as a crisis, because it is very dangerous for blood sugar to drop too low.

So, there are other hormones that rush in to work against insulin and raise blood sugar. One of these is epinephrine, better known as adrenaline. Epinephrine raises your blood sugar by turning off insulin release and telling your liver to break down some of its emergency glycogen supply into glucose and release it into the bloodstream. Epinephrine is an ancient “fight or flight” hormone—it’s produced when we are in danger, such as when a saber-toothed tiger wanders into our cave. It is designed to give our bodies a surge of energy to help prepare us to fight or run away, but if we don’t use that energy to fight or flee, it just tends to make us feel panicky, shaky, agitated, and irritable.

The epinephrine reaction is responsible for most symptoms of “hypoglycemia”, which can occur within a couple of hours of eating sweet or starchy foods. Other hormones that are released to counteract insulin include glucagon (which may cause hunger sensations, headaches, and stomach upset), cortisol (our “stress hormone”), and growth hormone. These hormones work together to turn off your insulin response and return your blood sugar to normal.

For some people, this unstable pattern of rising and falling blood sugar is happening to some degree several times per day. Because most people eat refined and high glycemic index carbohydrates every day, they may not be aware that their daily cycles of moodiness, hunger, and physical discomfort are tied to this invisible hormonal roller coaster.

Why do carbohydrates make some people sleepy?

Many people feel sleepy after they eat or drink carbohydrates. It is not unusual to look around the dinner table and find people nodding off after dessert, or wanting to take a nap after a big starchy holiday meal. Why would that be if sugar carbohydrates are supposed to give us energy?

Relatively new research (conducted in mice) suggests that this effect may be due to a specialized group of brain cells called “orexin/hypocretin” neurons. These cells are responsible for alertness, and they appear to be turned on by proteins and turned off by carbohydrates.1

How much carbohydrate do we need to eat?

NONE.

Once we are weaned from breast milk, we can live a whole lifetime without eating a single molecule of carbohydrate:

“The lower limit of dietary carbohydrate compatible with life apparently is ZERO [my emphasis], provided that adequate amounts of protein and fat are consumed.”

“There are traditional populations that ingested a high fat, high protein diet containing only a minimal amount of carbohydrate for extended periods of time (Masai), and in some cases for a lifetime after infancy (Alaska and Greenland Natives, Inuits, and Pampas indigenous people). There was no apparent effect on health or longevity. Caucasians eating an essentially carbohydrate-free diet, resembling that of Greenland natives, for a year tolerated the diet quite well. However, a detailed modern comparison with populations ingesting the majority of food energy as carbohydrate has never been done.”

—Institute of Medicine and the Food and Nutrition Board 2005. Dietary Reference Intakes for Macronutrients. National Academics Press

Doesn’t the brain require glucose to function?

Well, yes . . . but:

1. The brain doesn’t need very much glucose. Depending on circumstances, the brain needs between 30 and 130 grams (1/8 cup to 1/2 cup) per 24 hours.
2. The brain can burn other fuels besides glucose—it can burn ketones (which are made from fat) and lactate (which is created by working muscles).
3. Your liver can make all the glucose your brain needs out of protein. This process is called “gluconeogenesis,” which means “making sugar from scratch.” You don’t have to eat sugar to make blood sugar.

How might carbohydrates cause common diseases?

There is growing interest in and scientific momentum behind what is called “the carbohydrate hypothesis of disease.” This is the idea that most diseases of civilization are caused by our so-called “Western” diet, and that the ingredient in the Western diet that is most dangerous is refined carbohydrate. The diseases on this list1 include:

• Type 2 diabetes
• Obesity
• Coronary artery disease
• Cancer of certain kinds
• Hypertension (high blood pressure)
• Alzheimer’s disease
• Peripheral vascular disease
• Osteoporosis
• Acne
• Diverticulitis
• Appendicitis

As a psychiatrist, I strongly suspect that the modern diet is a major culprit in many common mental health disorders, as well. I encourage you to read my blog posts about low-carbohydrate diets and bipolar disorder and the role of sugar in ADHD.

There have been numerous traditional human societies, which have eaten diets high in carbohydrate and have been healthy; however the types of carbohydrates in these diets were unrefined and tended to be low in glycemic index. Therefore, we will focus on the role of refined and high glycemic index carbohydrates in disease. For the sake of efficiency, let’s refer to them as “fast carbs.” I will be writing more about the potential dangers of fast carbs in the future, but for now, here are just a few important ways that they could raise our risk for serious diseases.

Advanced glycation end products (AGE’s)

Fast carbs raise blood sugar levels, and excess blood sugar can bind to vital proteins, DNA, RNA, and fats in the body and damage them, sometimes beyond repair. This process is called “glycation”. Think of it this way: sugars make proteins sticky. Proteins are supposed to be able to fold and move in special ways to perform their various special functions, but they can’t do that if sugar is gumming up the works. When sugars bind permanently to proteins, they turn the proteins into nuisance compounds called “Advanced Glycation End Products” or AGE’s. AGE’s have been linked to a wide variety of chronic diseases, including heart disease, kidney failure, diabetic retinopathy, Alzheimer’s disease, and aging.1

Carbohydrates and oxidative damage

Fast carbs are “pro-oxidants.” This means that they have the power to damage important body molecules, such as DNA, by stealing their electrons away from them. Pro-oxidants are the opposite of anti-oxidants; they fight against each other. In a healthy body, pro-oxidants and the antioxidants are in balance. However, most of us are out of balance, most likely due to our Western diet, which is very high in pro-oxidants, such as refined carbohydrates. We are told all the time that we need to eat foods high in antioxidants but we are never told that we are supposed to avoid foods that are high in pro-oxidants! Perhaps if we weren’t eating so many pro-oxidants, scientists wouldn’t think we needed to add anti-oxidants to our bodies. [Read my post on Psychology Today, “The Antioxidant Myth” to learn more about this.]

Oxidative damage caused by pro-oxidants such as sugars can be the first step towards serious problems, such as cancer (by damaging DNA) and heart disease (by oxidizing cholesterol).

Carbohydrates and inflammation

Both glycation and oxidation trigger inflammation in the body. Physicians and scientists have come to understand that most common chronic diseases are rooted in inflammation. This is not necessarily the kind of inflammation we can see or feel—it is usually on a much smaller scale that we may not be aware of. For example, the cholesterol plaques that block arteries to the heart and cause heart attacks are found to contain all the mini-markers of inflammation when you look at them under a microscope. Even diseases such as depression are associated with mini-markers of inflammation. [You can learn more about inflammation and mental illness in my Psychology Today post]

Bottom line about carbohydrates

It is completely unnecessary to eat any carbohydrate once you are old enough to eat solid food.

Rapidly digested carbohydrates such as sugar and flour have the potential to disrupt our hormonal rhythms, our appetite regulation mechanism, and our internal pro-oxidant/anti-oxidant balance. They put us at risk for chronic inflammatory diseases, mood instability, and obesity.

Because carbohydrates are completely unnecessary, it would be wise to consider substantially reducing the amount of carbohydrate in your diet, especially refined and high glycemic index carbohydrate.

Next steps

I’ve given you a lot of information about carbohydrates to digest guilt-free, but don’t want to leave you hanging. The following suggestions include both further reading and practical help to implement changes in your diet if you choose to reduce your carbohydrate intake.

I recently wrote a series about fructose and glucose metabolism and insulin resistance that further explores some of the information mentioned above.

• “Has Fructose Been Framed” takes a more detailed look at how the liver processes glucose and fructose.
• “Why Sugar Is Bad for You: A Summary of the Research” more closely examines how insulin resistance contributes to major chronic illnesses such as diabetes type 2, cancer, high cholesterol, heart disease, fatty liver disease, gout, and obesity.
• “How to Diagnose, Prevent, and Treat Insulin Resistance” provides valuable tips on how to determine if you are insulin resistant (including a downloadable pdf with medical tests that you can discuss with your health care provider), guidelines for how many carbs are safe to eat based on your health status, and an infographic with tips for increasing insulin sensitivity.
• I wrote an entire post about carbohydrates and the hormonal roller coaster for Psychology Today: “Stabilize Your Mood with Food.“

You may also want to take the carbohydrate sensitivity quiz to get a sense of your personal level of carb sensitivity and if you are considering trying a low-carb or ketogenic diet, my “Ketogenic Diet 101” post is full of practical tips and resources that you may find helpful.

If you have questions or stories about your personal journey, please share them in the comments section. And if you know others who would benefit from this information, please share this page on your favorite social media site. Hope to see you in the comments!

Controversial carbohydrates! How can some carbohydrates—fruits, sweet potatoes, whole grains, and beans— be considered “good” and other carbohydrates—flour, sugar, and corn syrup—be considered “bad?” Doesn’t our brain need daily carbohydrate for energy? If so, how do people eating low-carb diets get by?

Let’s start with the basics . . .

What are carbohydrates?

Carbohydrates are sugars and starches. They are very simple molecules made out of carbon, hydrogen, and oxygen. All plants and animals can use carbohydrates for energy (and for building body parts and body chemicals).

What is the difference between sugars and starches?

“Sugars” are by definition very small. Glucose is a single-molecule sugar, or “monosaccharide.” Sucrose (table sugar) is a “disaccharide”, made of two molecules: one molecule of glucose plus one molecule of fructose (fruit sugar) linked together. Lactose (milk sugar) is also a disaccharide, made of one molecule of glucose plus one molecule of galactose linked together. These small sugars are sometimes referred to as “simple sugars.” Fruits are high in simple sugars.

“Starches” are big—they are made up of lots of simple sugars stuck together. Potato starch and corn starch are good examples. Starches are often referred to as “complex carbohydrates.” Most people are aware that grains, beans, nuts, seeds, and root vegetables are high in starches. However, animals also contain a small amount of starch that most people are less familiar with, called glycogen. This is a special starch designed especially for animals; plants do not contain any glycogen.

Storing sugar as starch

Humans store glycogen as an emergency source of carbohydrate. Glycogen is made of lots of glucose molecules linked together in short branches. If your blood sugar drops, or if you’re in an emergency situation and need fast energy, glycogen from the liver can be rapidly broken down into glucose and released immediately into the bloodstream.

The liver can only store somewhere between 250 and 400 calories worth of glycogen. (Glycogen is also stored in the muscles, but this glycogen is reserved exclusively for the muscles to use while exercising; it cannot be used to maintain blood sugar levels.) So, what does your liver do to make blood sugar if it runs out of glycogen between meals? It will turn to the protein in your muscles. The liver can turn muscle protein into glucose via a process called gluconeogenesis, which essentially means “making glucose from scratch.”

Why we store energy as fat

Starches are very dense and heavy. This is why we don’t store very much energy as glycogen—it would take up too much room and weigh too much. We store less than a day’s worth of energy as glycogen; the rest we store as fat.

Plants store their energy as starch, in thick, heavy roots and tubers and bulbs. That’s ok for them, because they don’t have to move, but imagine if we had to store all of our energy as starch—we’d have to carry around enormous lumps of carbohydrate—like gigantic potatoes growing underneath our skin—everywhere we went. And, if we overate and gained weight, the lumps would get so big and heavy that it would be impossible for us to move.

This is why animals like us, who need to move around, store energy as fat. Fat is much lighter and it is flexible, so it moves with us (ever try to bend a potato?). Plus, we can store lots and lots of it. There is a very low limit to the amount of glycogen we can store, but the amount of fat we can store is practically unlimited. (Just another clue that humans are designed to burn fat, not carbohydrate . . .)

Blood sugar regulation

All animals, including humans, have a simple sugar in their blood called glucose, which is also known as “blood sugar.” Glucose is used for fast energy by our cells. Because glucose is a monosaccharide (it exists as single molecules), it doesn’t have to be broken down—it is ready to burn.

It is critical that our blood sugar be kept in a very tight range for us to feel well and function properly. If blood sugar goes too high, we feel logey and foggy. Over long periods of time, high blood sugar (such as in untreated type 2 diabetes) can cause a variety of serious chronic health problems. However, if blood sugar drops too low, we are in immediate danger of serious consequences, such as seizure, coma, and death, because under normal circumstances, the brain requires some glucose to function.

Because tight blood sugar control is so important, we have a very sophisticated system for regulating it. If you eat a low-carbohydrate diet, your blood sugar levels tend to stay fairly even, but if you are like most people and eat carbohydrate throughout the day, your blood sugar will rise after you eat. It will rise even faster and higher if you eat refined or high glycemic index carbohydrates, such as sugar, flour, or fruit juice, because these types of carbohydrates are digested and absorbed very rapidly. How does the body manage these blood sugar surges?

How carbohydrates can make us fat

Let’s say you eat a popsicle. The simple sugars in the sweet popsicle are rapidly absorbed into your bloodstream, and your blood sugar quickly starts to rise. Since the body wants to harness that energy and prevent high blood sugar, your pancreas releases the hormone insulin into your bloodstream. Insulin lowers your blood sugar putting the body into sugar-burning, fat-storing mode. It literally turns off your body’s ability to burn fat so that excess sugar will be burned instead of fat. If your body has enough energy already and your cells don’t need to burn any more sugar, insulin tells the liver to turn the extra sugar into fat (lipogenesis), and then squirrels that fat away in your fat cells. That’s how sugar can make you fat.

Now, if you are not particularly carbohydrate sensitive, that may be the end of the story. You ate the popsicle, your blood sugar rose briefly, but insulin quickly took care of it, and now you’re fine. But what if you are carbohydrate sensitive? [To find out how carbohydrate-sensitive you are, take my free carbohydrate sensitivity quiz.]

Hypoglycemia and the invisible hormonal roller coaster

If you are carbohydrate sensitive (or have insulin resistance), you may have an exaggerated response to eating that popsicle. Not only does this mean that your blood sugar will rise more than usual, and stay higher for longer, it also means that your insulin level will rise more than usual, and stay higher for longer, causing your blood sugar to then drop too low or too fast. The body perceives this as a crisis, because it is very dangerous for blood sugar to drop too low.

So, there are other hormones that rush in to work against insulin and raise blood sugar. One of these is epinephrine, better known as adrenaline. Epinephrine raises your blood sugar by turning off insulin release and telling your liver to break down some of its emergency glycogen supply into glucose and release it into the bloodstream. Epinephrine is an ancient “fight or flight” hormone—it’s produced when we are in danger, such as when a saber-toothed tiger wanders into our cave. It is designed to give our bodies a surge of energy to help prepare us to fight or run away, but if we don’t use that energy to fight or flee, it just tends to make us feel panicky, shaky, agitated, and irritable.

The epinephrine reaction is responsible for most symptoms of “hypoglycemia”, which can occur within a couple of hours of eating sweet or starchy foods. Other hormones that are released to counteract insulin include glucagon (which may cause hunger sensations, headaches, and stomach upset), cortisol (our “stress hormone”), and growth hormone. These hormones work together to turn off your insulin response and return your blood sugar to normal.

For some people, this unstable pattern of rising and falling blood sugar is happening to some degree several times per day. Because most people eat refined and high glycemic index carbohydrates every day, they may not be aware that their daily cycles of moodiness, hunger, and physical discomfort are tied to this invisible hormonal roller coaster.

Why do carbohydrates make some people sleepy?

Many people feel sleepy after they eat or drink carbohydrates. It is not unusual to look around the dinner table and find people nodding off after dessert, or wanting to take a nap after a big starchy holiday meal. Why would that be if sugar carbohydrates are supposed to give us energy?

Relatively new research (conducted in mice) suggests that this effect may be due to a specialized group of brain cells called “orexin/hypocretin” neurons. These cells are responsible for alertness, and they appear to be turned on by proteins and turned off by carbohydrates.1

How much carbohydrate do we need to eat?

NONE.

Once we are weaned from breast milk, we can live a whole lifetime without eating a single molecule of carbohydrate:

“The lower limit of dietary carbohydrate compatible with life apparently is ZERO [my emphasis], provided that adequate amounts of protein and fat are consumed.”

“There are traditional populations that ingested a high fat, high protein diet containing only a minimal amount of carbohydrate for extended periods of time (Masai), and in some cases for a lifetime after infancy (Alaska and Greenland Natives, Inuits, and Pampas indigenous people). There was no apparent effect on health or longevity. Caucasians eating an essentially carbohydrate-free diet, resembling that of Greenland natives, for a year tolerated the diet quite well. However, a detailed modern comparison with populations ingesting the majority of food energy as carbohydrate has never been done.”

—Institute of Medicine and the Food and Nutrition Board 2005. Dietary Reference Intakes for Macronutrients. National Academics Press

Doesn’t the brain require glucose to function?

Well, yes . . . but:

1. The brain doesn’t need very much glucose. Depending on circumstances, the brain needs between 30 and 130 grams (1/8 cup to 1/2 cup) per 24 hours.
2. The brain can burn other fuels besides glucose—it can burn ketones (which are made from fat) and lactate (which is created by working muscles).
3. Your liver can make all the glucose your brain needs out of protein. This process is called “gluconeogenesis,” which means “making sugar from scratch.” You don’t have to eat sugar to make blood sugar.

How might carbohydrates cause common diseases?

There is growing interest in and scientific momentum behind what is called “the carbohydrate hypothesis of disease.” This is the idea that most diseases of civilization are caused by our so-called “Western” diet, and that the ingredient in the Western diet that is most dangerous is refined carbohydrate. The diseases on this list1 include:

• Type 2 diabetes
• Obesity
• Coronary artery disease
• Cancer of certain kinds
• Hypertension (high blood pressure)
• Alzheimer’s disease
• Peripheral vascular disease
• Osteoporosis
• Acne
• Diverticulitis
• Appendicitis

As a psychiatrist, I strongly suspect that the modern diet is a major culprit in many common mental health disorders, as well. I encourage you to read my blog posts about low-carbohydrate diets and bipolar disorder and the role of sugar in ADHD.

There have been numerous traditional human societies, which have eaten diets high in carbohydrate and have been healthy; however the types of carbohydrates in these diets were unrefined and tended to be low in glycemic index. Therefore, we will focus on the role of refined and high glycemic index carbohydrates in disease. For the sake of efficiency, let’s refer to them as “fast carbs.” I will be writing more about the potential dangers of fast carbs in the future, but for now, here are just a few important ways that they could raise our risk for serious diseases.

Advanced glycation end products (AGE’s)

Fast carbs raise blood sugar levels, and excess blood sugar can bind to vital proteins, DNA, RNA, and fats in the body and damage them, sometimes beyond repair. This process is called “glycation”. Think of it this way: sugars make proteins sticky. Proteins are supposed to be able to fold and move in special ways to perform their various special functions, but they can’t do that if sugar is gumming up the works. When sugars bind permanently to proteins, they turn the proteins into nuisance compounds called “Advanced Glycation End Products” or AGE’s. AGE’s have been linked to a wide variety of chronic diseases, including heart disease, kidney failure, diabetic retinopathy, Alzheimer’s disease, and aging.1

Carbohydrates and oxidative damage

Fast carbs are “pro-oxidants.” This means that they have the power to damage important body molecules, such as DNA, by stealing their electrons away from them. Pro-oxidants are the opposite of anti-oxidants; they fight against each other. In a healthy body, pro-oxidants and the antioxidants are in balance. However, most of us are out of balance, most likely due to our Western diet, which is very high in pro-oxidants, such as refined carbohydrates. We are told all the time that we need to eat foods high in antioxidants but we are never told that we are supposed to avoid foods that are high in pro-oxidants! Perhaps if we weren’t eating so many pro-oxidants, scientists wouldn’t think we needed to add anti-oxidants to our bodies. [Read my post on Psychology Today, “The Antioxidant Myth” to learn more about this.]

Oxidative damage caused by pro-oxidants such as sugars can be the first step towards serious problems, such as cancer (by damaging DNA) and heart disease (by oxidizing cholesterol).

Carbohydrates and inflammation

Both glycation and oxidation trigger inflammation in the body. Physicians and scientists have come to understand that most common chronic diseases are rooted in inflammation. This is not necessarily the kind of inflammation we can see or feel—it is usually on a much smaller scale that we may not be aware of. For example, the cholesterol plaques that block arteries to the heart and cause heart attacks are found to contain all the mini-markers of inflammation when you look at them under a microscope. Even diseases such as depression are associated with mini-markers of inflammation. [You can learn more about inflammation and mental illness in my Psychology Today post]

Bottom line about carbohydrates

It is completely unnecessary to eat any carbohydrate once you are old enough to eat solid food.

Rapidly digested carbohydrates such as sugar and flour have the potential to disrupt our hormonal rhythms, our appetite regulation mechanism, and our internal pro-oxidant/anti-oxidant balance. They put us at risk for chronic inflammatory diseases, mood instability, and obesity.

Because carbohydrates are completely unnecessary, it would be wise to consider substantially reducing the amount of carbohydrate in your diet, especially refined and high glycemic index carbohydrate.

Next steps

I’ve given you a lot of information about carbohydrates to digest guilt-free, but don’t want to leave you hanging. The following suggestions include both further reading and practical help to implement changes in your diet if you choose to reduce your carbohydrate intake.

I recently wrote a series about fructose and glucose metabolism and insulin resistance that further explores some of the information mentioned above.

• “Has Fructose Been Framed” takes a more detailed look at how the liver processes glucose and fructose.
• “Why Sugar Is Bad for You: A Summary of the Research” more closely examines how insulin resistance contributes to major chronic illnesses such as diabetes type 2, cancer, high cholesterol, heart disease, fatty liver disease, gout, and obesity.
• “How to Diagnose, Prevent, and Treat Insulin Resistance” provides valuable tips on how to determine if you are insulin resistant (including a downloadable pdf with medical tests that you can discuss with your health care provider), guidelines for how many carbs are safe to eat based on your health status, and an infographic with tips for increasing insulin sensitivity.
• I wrote an entire post about carbohydrates and the hormonal roller coaster for Psychology Today: “Stabilize Your Mood with Food.“

You may also want to take the carbohydrate sensitivity quiz to get a sense of your personal level of carb sensitivity and if you are considering trying a low-carb or ketogenic diet, my “Ketogenic Diet 101” post is full of practical tips and resources that you may find helpful.

If you have questions or stories about your personal journey, please share them in the comments section. And if you know others who would benefit from this information, please share this page on your favorite social media site. Hope to see you in the comments!