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When you think of animal fat, what comes to mind? Unsightly blobs of cellulite? Artery-clogging strips of gristle to be trimmed off your steak and tossed into the trash? Or a sophisticated substance that contains within it the secret to human intelligence?

Fun facts about fat

We think of fat as bad—the less of it we eat, and the less of it we carry on our bodies, the better—but this isn’t the right way to think about it. Fat is not just for insulation and energy storage, it’s also for nutrient absorption, cell signaling, immune function, and many other critical processes. Many people think the main difference between plant and animal fats is that animal-sourced foods contain more saturated fat, but here are a few fun, fatty facts that may surprise you:

• All whole plant and animal foods naturally contain a mixture of saturated and unsaturated fats.
• Some plant foods are higher in saturated fat than animal foods, with coconut oil topping the charts at 90 percent saturated fat. That’s more than twice the saturated fat found in beef fat (tallow).
• The primary type of fat found in pork is a monounsaturated fatty acid (MUFA) called oleic acid, the same fat found in olive oil.

For decades now, we’ve been told to avoid saturated fats—particularly those from animal foods—and to consume “heart-healthy,” cholesterol-free fats from plant foods such as seeds, nuts, and olives. Public health officials say these plant fats are important because they contain two essential PUFAs (polyunsaturated fatty acids) that the human body can’t manufacture:

• The essential dietary omega-3 PUFA is called alpha-linolenic acid (ALA for short)
• The essential dietary omega-6 PUFA is called linoleic acid (LA for short)

What often goes unsaid is that both ALA and LA are found in a wide variety of both plant and animal foods, so it is rather easy to obtain both of these PUFAs regardless of your dietary preferences, so long as you include enough fat in your diet.

But here’s the rub: Our bodies really aren’t looking for ALA and LA; they’re looking for something better. ALA and LA are considered “parent” omegas because they are used to manufacture the omegas we actually need: EPA, DHA, and ARA—none of which exist in plant foods.

EPA (eicosapentaenoic acid) is an omega-3 PUFA that serves primarily anti-inflammatory and healing functions.

ARA (arachidonic acid) is an omega-6 often thought of as a “bad” fatty acid because it promotes inflammation and is only found in animal foods (and algae). Yet ARA shoulders countless other responsibilities, and even promotes healing. Arachidonic acid recently stepped into my office for a long-overdue therapy session, which takes you inside the tortured mind of this beneficial molecule and explains why there’s no need to fear consuming it.

But what about DHA? So glad you asked…

Introducing DHA

Our brains are extremely rich in fat. About two-thirds of the human brain is fat, and a full 20 percent of that fat is a very special omega-3 fatty acid called docosahexaenoic acid, or DHA.

DHA is an ancient molecule so useful to us and our fellow vertebrates (creatures with backbones) that it has remained unchanged for more than 500 million years of evolution. What makes this particular PUFA so irreplaceable?

DHA’s job description is a lengthy one. Among many other functions, DHA participates in the formation of myelin, the white matter that insulates our brain circuits. It also helps maintain the integrity of the blood-brain barrier, which keeps the brain safe from unwanted outside influences.

Perhaps most importantly, DHA is critical to the development of the human cortex—the part of the brain responsible for higher-order thinking. Without DHA, the highly sophisticated connections necessary for sustained attention, decision-making, and complex problem-solving do not form properly. It has been hypothesized that without DHA, consciousness and symbolic thinking—hallmarks of the human race—would be impossible.

DHA plays a “unique and indispensable role” in the “neural signaling essential for higher intelligence.” —Simon Dyall Ph.D., Lipid Research Scientist Bournemouth University, UK

Professor Michael Crawford, a pioneering British scientist who has been studying essential fatty acids for 50 years, theorizes that DHA’s special configuration lends it unique quantum mechanical properties that allow it to buffer electron flow. This may explain why we find it in places throughout the brain and body where electricity is important: synapses where brain cell signaling takes place; mitochondria, where the electron transport chain is busy turning food into stored energy; and the retina of the eye, where photons of sunlight are transformed into electrical information.

This is a truly miraculous molecule. Plants don’t have it, because plants don’t need it.

Baby, have we got a molecule for you…

The most rapid phase of development of the infant cortex takes place between the beginning of the third trimester of pregnancy and age 2. If enough DHA isn’t available to the baby during this critical 27-month window, it is unclear whether the consequences can be completely undone. In fact, we do see lower levels of DHA in people diagnosed with psychiatric disorders, including those which manifest early in life, such as autistic spectrum disorders and ADHD.

“Similar to children and adolescents born preterm, patients with ADHD, mood disorders, and psychotic disorders also exhibit decreased frontal white matter tract integrity and reduced functional connectivity within cortical networks. Together these findings support the hypothesis that perinatal deficits in DHA accrual may contribute to diminished cortical circuit development observed in major psychiatric disorders.” [McNamara RK 2015]

Plant foods contain absolutely no DHA

For those who choose vegan diets, it is important to know that plant foods contain no DHA. The omega-3 fatty acid found in plant foods like flax, walnut, and chia is alpha-linolenic acid (ALA). Unfortunately, it appears to be rather difficult for the adult human body to make DHA out of ALA, with most studies finding a conversion rate of less than 10 percent:

Source: Georgia Ede

Note that quite a few studies find a conversion rate of 0 percent.

Whether this pathway can generate adequate amounts of DHA in all adults under all circumstances continues to be a topic of debate. Some scientists have advocated that DHA, rather than ALA, should be officially considered the essential omega-3 fatty acid. Even vocal advocates of plant-based diets, such as the authors of the recent EAT-Lancet report, acknowledge that it is unclear how much ALA one needs to consume to fulfill DHA requirements.

Indeed, it appears that the fewer animal foods we eat, the lower our DHA levels tend to be:

Source: Georgia Ede

However, when it comes to children younger than 2 years old, the science is clear that this conversion pathway cannot and should not be relied upon to keep pace with the DHA demands of the rapidly growing body and brain. Therefore, most experts agree that caretakers should provide infants and very young children with dietary or supplemental sources of DHA, as ALA alone is not sufficient to support healthy infant development.

DHA status and intake recommendations are based on blood levels, not brain levels. Unfortunately, there is no way to measure brain DHA levels in living human beings, and it’s unclear whether blood levels reflect brain levels.

Bearing this in mind, it has been estimated that as many as 80 percent of Americans have suboptimal blood levels of DHA.

DHA: Don’t leave home without it

Include animal-sourced foods in your diet if you can

The USDA has not established specific DHA intake targets for the general population; instead, it recommends everyone consume at least eight ounces of seafood per week. The easiest way to obtain DHA is to include some fatty fish in your diet, but as you can see from the table below, there are other options.

Source: Data from USDA National Nutrient Database 2016.

Minimize consumption of vegetable oils

Nearly all processed foods, prepared hot foods, packaged snacks, and convenience foods are made with refined vegetable oils, such as soybean or sunflower oil. Most vegetable oils are extremely, unnaturally high in LA (linoleic acid), an omega-6 fatty acid that reduces the production and effectiveness of DHA within your body. Excess linoleic acid can tilt your immune system too far towards inflammation and away from healing, so there are many reasons to minimize your consumption of vegetable oils. Your best plant oil choices are olive oil, avocado oil, coconut oil, or red palm oil. If you must include refined vegetable oil, canola oil and palm kernel oil are low in linoleic acid. Lowering your vegetable oil intake can increase the availability of DHA in your body, decreasing your need for dietary and/or supplemental DHA. The presence of high amounts of linoleic acid in the typical modern diet may help to explain why so many people appear to have low DHA levels despite the fact that most people do include animal foods in their diet already.

If you choose a plant-based diet, supplement properly

Thankfully, vegetarian and vegan-friendly DHA supplements extracted from algae are available. [Algae are neither plants nor animals . . . discuss!] These supplements are more expensive and contain lower concentrations of DHA than fish or krill oil supplements (meaning higher doses are recommended), but may be important for maintaining healthy DHA levels, particularly in mothers and babies during pregnancy and while breastfeeding. Directly consuming seaweed and other forms of edible algae instead of taking algae oil extracts is unreliable, because it’s unclear whether the DHA within these fibrous foods can be released and absorbed by the human body; in other words, the DHA in edible algae may not be bioavailable. All baby formula in the U.S. is supplemented with DHA already, in an effort to mirror human mother’s milk, which naturally contains DHA. If weaning your child before age 2, be sure to include DHA in your child’s diet as food or supplements.

If you have psychiatric symptoms, consider supplementation

There have been numerous clinical trials of omega-3 supplements in the management of psychiatric disorders. You may be surprised to hear that most of these studies have generated only weak or mixed results. There are many possible reasons for this, not the least of which may be that the amount of linoleic acid in the diet was not taken into consideration. In other words, taking a decent dose of omega-3s without also lowering your linoleic acid consumption (by avoiding vegetable oils) may not be very helpful. However, supplementation is widely viewed as safe, and some studies noted modest benefits at doses of (combined EPA+DHA) of 1,000 to 2,000 mg per day, particularly for people with depression.

Unanswered questions

I titled this post “The Brain Needs Animal Fat,” because although DHA does exist in algae, algae are not plants, and we don’t know if we can access the DHA within edible algae without special extraction methods. Prior to the manufacturing of algae-derived supplements (which only became available recently), the only pre-formed DHA naturally bioavailable to everyone would have come from animal foods. For those who choose a vegan diet, I fully support and recommend algae-based supplements.

It is difficult to be sure precisely how much DHA we need, and both conversion rates and availability can vary significantly depending on age, gender, genetics, and dietary composition.

There are many questions left unanswered that go beyond the scope of this post and may deserve a follow-up post. For example, if most land animals are extremely low in DHA, does that mean everyone needs to eat seafood? Are wild land animal foods higher in DHA than standard land animal foods we find in the grocery store? How do adults choosing plant-based diets know whether they can rely on their ALA conversion pathway? Could eliminating processed foods and vegetable oils completely eliminate the apparent requirement for animal-sourced DHA (or algae oil supplementation)? Does eating a low-carbohydrate diet affect the conversion rate from ALA to DHA? Should you get tested for omega-3 deficiencies, and if so, how? Are there any disadvantages to obtaining DHA from supplements as opposed to obtaining them from animal foods?

The bottom line about DHA

Until next time, minimizing refined vegetable oils and other processed foods, and either including some animal foods in the diet or supplementing appropriately, seem to be reasonable options that likely minimize our risk.

One thing is clear. DHA is a wondrous fatty acid that the human body cannot function without, and it deserves our admiration and respect. While it is important for all of us, when it comes to building the brains of the future, it is precious and irreplaceable.

Facebook Image Credit: Rido/Shutterstock

So a fatty acid walks into a psychiatrist’s office.

Psychiatrist: What brings you in today?

Fatty Acid: I’m depressed and lonely. Most people completely ignore me and don’t even know I exist. And to make matters worse, prominent public health officials and influential physicians spread rumors about me, saying all I do is cause inflammation and chronic disease. It hurts my feelings.

Psychiatrist: Well, do you cause inflammation?

Fatty Acid: Yes, okay, okay, it’s true, I do cause inflammation, but you gotta understand—it’s complica—

Psychiatrist: I’m sorry for interrupting you. I’d like to try to help you, but before we dig deeper, please fill out this demographics form I need for billing purposes.

Name: Arachidonic Acid (ARA)

Family: Omega-6 polyunsaturated fatty acid (PUFA)

Age: millions of years old

Address: animal cell membranes

Occupation:

• Inflammation promoter
• Brain developer
• Membrane fluidity maintenance engineer
• Muscle repairman
• Brain cell communicator
• Cholesterol metabolizer
• Stomach acid inhibitor
• Uterine contractor
• Coagulation coordinator
• Kidney filtration manager
• HPA axis influencer
• Endocannabinoid synthesizer
• Blood vessel dilator
• Airway diameter controller
• Intestinal motility foreman
• Healing promoter

P: Interesting. You sure you’re not depressed from working too hard? Look at all these jobs. Maybe you need some time off.

ARA: You see what I’m talking about! Nobody appreciates all the things I do for them. Most people have no idea that they can’t live without me.

P: But surely you can understand why people are afraid of you. Right there at the top of your list is inflammation.

ARA: You say that like it’s a bad thing. I can’t believe you went to medical school and don’t realize the importance of inflammation. Inflammation is the critical first step in the body’s response to things like infections and injuries. And if you’d bothered to read all the way to the bottom of the list, you would have noticed that I don’t just promote inflammation—I also promote healing. I’m not just one-dimensional. Peel the onion.

P: I can’t help but notice that you’re only located in animal foods—that’s another justifiable reason why people avoid you like the plague, is it not?

ARA: Look, I know you’re only in your fifties, so you’re not going to believe me, but I’ve been around for millions of years, and I’m telling you it never used to be this way. I used to be popular, valued. I used to be a contender. People used to prize animal foods for being nutritious, now they demonize the very nutrients within them that make them essential to human life. If you think I’m just playing the victim card here, you should know I’m not the only one. Go ask heme iron, or cholesterol, or carnitine—they’ll tell you. It’s crazy-making. Nothing makes sense anymore. [chokes back tears] I’m thinking of leaving this world behind.

P: You don’t mean…

ARA: Yep. The big A. Apoptosis. I’m going to do myself in. Being able to trigger cell death is just another one of my superpowers. I didn’t put it on the list…for obvious reasons.

P: I’m beginning to understand how painful your existence feels. Looking over that list again, it’s clear you have so much to give. People may not like you, but they still need you, right? Are you considered an essential nutrient?

ARA: Public health officials don’t consider me essential, but a growing number of scientists disagree and are advocating on my behalf.

P: Well, there, you see? Not everyone in the world is against you.

ARA: When did I ever say that? Review your notes, doc. I’m not paranoid, I’m depressed. Now can we get back to my real problem?

P: Ok, I’m sorry. Please go on. Why do officials think we don’t need you?

ARA: There is a biochemical pathway in human cells that can turn linoleic acid into arachidonic acid. Linoleic acid is found in plant and animal foods, so it’s easy to obtain regardless of dietary preferences. Nearly a century ago, it was shown that linoleic acid can be used to reverse obvious symptoms of essential fatty acid deficiency (EFAD), a rare disorder caused by fat-free diets, so linoleic acid was crowned as the essential omega-6 fatty acid.

P: This looks like an open-and-shut case in support of linoleic acid as the most important omega-6, but I sense you’d disagree?

ARA: Now you’re catching on. It turns out that this pathway can also run in reverse, so you can make linoleic acid out of arachidonic acid, too. We also now know that arachidonic acid works just as well for preventing EFAD symptoms.

P: Interesting…so which one of you is the true essential omega-6? Or does it even matter?

ARA: Well, it matters if you’re a baby. The pathway from linoleic acid to arachidonic acid doesn’t seem to operate well in human infants. For example, when babies are given a high-linoleic acid formula (free of arachidonic acid), their blood levels of arachidonic acid don’t rise, they plummet—while linoleic acid appears to simply pile up in the bloodstream. If babies could easily convert linoleic acid into arachidonic acid, you’d expect the opposite result.

It is well established that the infant’s brain requires arachidonic acid for proper growth and development. Human mother’s milk naturally contains significant quantities of arachidonic acid, whereas the milk of other mammals contains only trace amounts, suggesting I play a special role in human development. And get this: the human placenta actively transfers arachidonic acid from mother to fetus. Now I ask you–would evolution have installed this special delivery system for an inflammatory, disease-causing molecule? I think not–and the Food and Agriculture Association/World Health Organization agrees with me, as they began recommending many years ago that infant formula be fortified with arachidonic acid.

P: Mmm hmmm…

ARA: The other major problem is that we’re not sure how well the conversion from linoleic acid to arachidonic acid operates in adults either. In study after study, when scientists gave linoleic acid supplements to people eating a typical modern diet, arachidonic acid levels in the blood didn’t budge, even when very high doses of linoleic acid were used. Is this because this pathway is a poor generator of arachidonic acid? Or is it because the typical modern diet includes ready-made arachidonic acid from animal foods AND extremely high amounts of linoleic acid from vegetable oils. Maybe the system was already saturated with arachidonic acid and the pathway didn’t need to switch on to manufacture more? We don’t know. Are you following me so far?

P: [snoring] What? Oh…yes, yes, I completely agree. That’s fascinating.

ARA: Seriously? Did you fall asleep on me? I’d storm outta here right now except you’re the only psychiatrist in a 100-mile radius who takes my insurance, so I’m staying for the whole 50 minutes. Should I go over the science again?

P: No, I think I get the gist. You’re a vital molecule we can’t live without and it’s unclear if linoleic acid can completely replace you at all stages of life. Does this mean that people who don’t include animal foods in their diets don’t have enough arachidonic acid in their brains and bodies?

ARA: Unfortunately there is no way to measure arachidonic acid levels in the brains of living people. As for bloodstream levels, of the three very small studies I could find [one, two, three], only one showed that vegans had lower circulating arachidonic acid levels compared to omnivores. So it appears that adults may be able to maintain adequate blood levels of arachidonic acid without eating animal foods so long as they consume enough linoleic acid. Linoleic acid is present in reasonable amounts in whole plant and animal foods but is particularly easy to obtain from processed foods made with refined seed oils, aka “vegetable oils.” Soybean oil, for example, contains about 50% linoleic acid.

Source: Suzi Smith, used with permission

P: So, vegetable oil for the win!

ARA: Not so fast. Advocates for plant-based diets warn people about me causing inflammation, but they don’t usually warn people about linoleic acid causing inflammation. If linoleic acid turns into arachidonic acid, and arachidonic acid promotes inflammation, then linoleic acid does too, right? You can’t have it both ways. If you’re going to demonize one, you have to demonize the other. Instead, their mantra is “meat bad, vegetable oil good.”

P: So you’re BOTH bad?

ARA: No, I’m good. I’m GOOD I tell you. Yes, I cause inflammation, but I don’t just run around willy-nilly causing inflammation for inflammation’s sake. Why would I want to do that? I only mount an inflammatory response in reaction to real threats.

P: So why do so many people blame you for causing chronic inflammatory diseases?

ARA: All of those rumors about me come from epidemiological studies—deeply flawed, questionnaire-based guesses about the relationship between foods and diseases—not from scientific experiments. All of the human experimental studies conducted so far show that raising levels of arachidonic acid using supplements does NOT cause signs of unnecessary or harmful inflammation.

P: So it’s really a matter of personal choice then, right? People can decide whether they prefer to obtain arachidonic acid directly from animal foods or indirectly from linoleic acid found in plant foods?

ARA: Unless you’re an infant, the available science suggests you can meet your basic arachidonic acid requirements if you are consuming vegetable oils. Because research studies use vegetable oils as their source of linoleic acid, we don’t know whether you can meet your daily needs from whole food plant sources of linoleic acid, because as far as I know, those experiments haven’t been done, but it’s certainly plausible.

If people choose to include vegetable oils in their diets, as recommended by the USDA and the recent EAT-Lancet report, they should know that most vegetable oils are ultra-processed, industrially-produced and unnaturally, exceedingly high in linoleic acid compared to whole foods. Excess linoleic acid promotes inflammation by competing with EPA, an anti-inflammatory omega-3 fatty acid, so there is some risk involved in obtaining your omega-6s from vegetable oils. Somehow your species was able to survive for nearly two million years without processed vegetable oils, so how they suddenly came to be considered important to human health in the 20th century—not long after they were invented by food manufacturers—is a head-scratcher.

P: So our time is just about up. If I understand you correctly, what you’re saying is that the simplest, safest and most reliable way to guarantee you’re getting enough arachidonic acid is to include animal foods in your diet.

ARA: Exactly. If people are avoiding meat because they think it causes inflammation, they can relax. If they are worried about inflammation, they should pay attention to the refined vegetable oils like soybean and sunflower oil, and the refined carbohydrates like sugar, flour, fruit juice and processed cereals in their diet instead.

The jury is still out about whether I should be considered essential beyond infancy, but there’s no doubt that I am good for people. I’m a nice guy. Really I am. Hardworking, reliable, and multi-talented. Wow, I feel a lot better now that I’ve had a chance to vent. Thanks, Doc.

P: I’m glad you’re feeling some relief, but I don’t think you’re out of the woods yet. You’re up against a growing culture of anti-meat sentiment in this world. You are going to need ongoing support…I recommend years of intensive psychotherapy.

A: Who’s helping who here? Fine, you’re probably right. There are plenty of logical reasons why people should pay attention to me and consider me an essential nutrient, but because I only exist in animal foods, there’s tremendous emotional resistance to my existence. Arachiphobia is likely to spread….woe is me. Same time next week?