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Tag: animal fat

  • Eating with Hypothyroidism and Hyperthyroidism  | NutritionFacts.org

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    Is the apparent protection of plant-based diets for thyroid health due to the exclusion of animal foods, the benefits of plant foods, or both?

    Several autoimmune diseases affect the thyroid gland, and Graves’ disease and Hashimoto’s thyroiditis are the most common. Graves’ disease results in hyperthyroidism, an overactive thyroid gland. Though slaughter plants are supposed to remove animals’ thyroid glands as they “shall not be used for human food,” should some neck meat slip in, you can suffer a similar syndrome called Hamburger thyrotoxicosis. That isn’t from your body making too much thyroid hormone, though. Rather, it’s from your body eating too much thyroid hormone. Graves’ disease is much more common, and meat-free diets may be able to help with both diseases, as plant-based diets may be associated with a low prevalence of autoimmune disease in general, as observed, for example, in rural sub-Saharan Africa. Maybe it’s because plants are packed with “high amounts of antioxidants, possible protective factors against autoimmune disease,” or because they’re packed with anti-inflammatory compounds. After all, “consuming whole, plant-based foods is synonymous with an anti-inflammatory diet.” But you don’t know until you put it to the test.

    It turns out that the “exclusion of all animal foods was associated with half the prevalence of hyperthyroidism compared with omnivorous diets. Lacto-ovo [dairy-and-egg] and pesco [fish] vegetarian diets were associated with intermediate protection.” But, for those eating strictly plant-based, there is a 52 percent lower odds of hyperthyroidism.

    As I discuss in my video The Best Diet for Hypothyroidism and Hyperthyroidism, this apparent protection “may be due to the exclusion of animal foods, the [beneficial] effects of plant foods, or both. Animal foods like meat, eggs, and dairy products may contain high oestrogen concentrations, which have been linked to autoimmunity in cell and animal studies.” Or it could be because the decrease in animal protein by excluding animal foods may downregulate IGF-1, which is not just a cancer-promoting growth hormone, but may play a role in autoimmune diseases. The protection could also come from the goodness in plants that may “protect cells against autoimmune processes,” like the polyphenol phytochemicals, such as flavonoids found in plant foods. Maybe it’s because environmental toxins build up in the food chain. For example, fish contaminated with industrial pollutants, like PCBs, are associated with an increased frequency of thyroid disorders.

    But what about the other autoimmune thyroid disease, Hashimoto’s thyroiditis, which, assuming you’re getting enough iodine, is the primary cause of hypothyroidism, an underactive thyroid gland? Graves’ disease wasn’t the only autoimmune disorder that was rare or virtually unknown among those living in rural sub-Saharan Africa, eating near-vegan diets. They also appeared to have less Hashimoto’s.

    There is evidence that those with Hashimoto’s have compromised antioxidant status, but we don’t know if it’s cause or effect. But if you look at the dietary factors associated with blood levels of autoimmune anti-thyroid antibodies, animal fats seem to be associated with higher levels, whereas vegetables and other plant foods are associated with lower levels. So, again, anti-inflammatory diets may be useful. It’s no surprise, as Hashimoto’s is an inflammatory disease—that’s what thyroiditis means: inflammation of the thyroid gland.

    Another possibility is the reduction in intake of methionine, an amino acid concentrated in animal protein, thought to be one reason why “regular consumption of whole-food vegan diets is likely to have a favourable influence on longevity through decreasing the risk of cancer, coronary [heart] disease, and diabetes.” Methionine restriction improves thyroid function in mice, but it has yet to be put to the test for Hashimoto’s in humans.

    If you compare the poop of patients with Hashimoto’s to controls, the condition appears to be related to a clear reduction in the concentration of Prevotella species. Prevotella are good fiber-eating bugs known to enhance anti-inflammatory activities. Decreased Prevotella levels are also something you see in other autoimmune conditions, such as multiple sclerosis and type 1 diabetes. How do you get more Prevotella? Eat more plants. If a vegetarian goes on a diet of meat, eggs, and dairy, within as few as four days, their levels can drop. So, one would expect those eating plant-based diets to have less Hashimoto’s, but in a previous video, I expressed concern about insufficient iodine intake, which could also lead to hypothyroidism. So, which is it? Let’s find out.

    “In conclusion, a vegan diet tended to be associated with lower, not higher, risk of hypothyroid disease.” Why “tended”? The associated protection against hypothyroidism incidence and prevalence studies did not reach statistical significance. It wasn’t just because they were slimmer either. The lower risk existed even after controlling for body weight. So, researchers think it might be because animal products may induce inflammation. The question I have is: If someone who already has Hashimoto’s, what happens if they change their diet? That’s exactly what I’ll explore next.

    This is the third in a four-video series on thyroid function. The first two were Are Vegans at Risk for Iodine Deficiency? and Friday Favorites: The Healthiest Natural Source of Iodine.

    Stay tuned for the final video: Diet for Hypothyroidism: A Natural Treatment for Hashimoto’s Disease. 

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    Michael Greger M.D. FACLM

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  • Is Stainless Steel or Cast Iron Cookware Best? Is Teflon Safe? | NutritionFacts.org

    Is Stainless Steel or Cast Iron Cookware Best? Is Teflon Safe? | NutritionFacts.org

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    What is the best type of pots and pans to use?

    In my last video, I expressed concerns about the use of aluminum cookware. So, what’s the best type of pots and pans to use? As I discuss in my video Stainless Steel or Cast Iron: Which Cookware Is Best? Is Teflon Safe?, stainless steel is an excellent option. It’s the metal chosen for use “in applications where safety and hygiene are considered to be of the utmost importance, such as kitchenware.” But what about studies showing that the nickel and chromium in stainless steel, which keeps the iron in stainless unstained by rust, can leach into foods during cooking? The leaching only seems to occur when the cookware is brand new. “Metal leaching decreases with sequential cooking cycles and stabilizes after the sixth cooking cycle,” after the sixth time you cook with it. Under more common day-to-day conditions, the use of stainless steel pots is considered to be safe even for most people who are acutely sensitive to those metals. 

    A little leaching metal can even be a good thing in the case of straight iron, like a cast iron skillet, which can have the “beneficial effect” of helping to improve iron status and potentially reduce the incidence of iron deficiency anemia among children and women of reproductive age. The only caveat is that you don’t want to fry in cast iron. Frying isn’t healthy regardless of cookware type, but, at hot temperatures, vegetable oil can react with the iron to create trans fats. 

    What about using nonstick pans? Teflon, also known as polytetrafluoroethylene (PTFE), “is used as an inner coating material in nonstick cookware.” Teflon’s dark history was the subject of a 2019 movie called Dark Waters, starring Mark Ruffalo and Anne Hathaway. Employees in DuPont’s Teflon division started giving birth to babies with deformities before “DuPont removed all female staff” from the unit. Of course, the corporation buried it all, hiding it from regulators and the public. “Despite this significant history of industry knowledge” about how toxic some of the chemicals used to make Teflon were, it was able to keep it hidden until, eventually, it was forced to settle for more than half a billion dollars after one of the chemicals was linked to “kidney and testicular cancers, pregnancy-induced hypertension, ulcerative colitis, and high cholesterol.”

    “At normal cooking temperatures, PTFE-coated cookware releases various gases and chemicals that present mild to severe toxicity.” As you can see below and at 2:38 in my video, different gases are released at different temperatures, and their toxic effects have been documented. 

    You’ve heard of “canaries in the coal mine”? This is more like “canaries in the kitchen, as cooking with Teflon cookware is well known to kill pet birds,” and Teflon-coated heat lamp bulbs can wipe out half a flock of chickens. 

    “Apart from the gases released during heating the cooking pans, the coating itself starts damaging after a certain period. It is normally advised to use slow heating when cooking in Teflon-coated pans,” but you can imagine how consumers might ignore that. And, if you aren’t careful, some of the Teflon can start chipping off and make its way into the food, though the effects of ingestion are unknown.

    I could find only one study that looks at the potential human health effects of cooking with nonstick pots and pans. Researchers found that the use of nonstick cookware was associated with about a 50 percent increased risk of colorectal cancer, but that may be because of what they were cooking. “Non-stick cookware is used in hazardous cooking methods (i.e. broiling, frying, grilling or barbecuing) at high temperatures mainly for meat, poultry or fish,” in which carcinogenic heterocyclic amines (HCA) are formed from the animal protein. Then, the animal fat can produce another class of carcinogens called polycyclic aromatic hydrocarbons (PAH). Though it’s possible it was the Teflon itself, which contains suspected carcinogens like that C8 compound from the movie Dark Waters, also known as PFOA, perfluorooctanoic acid.

    “Due to toxicity concerns, PFOA has been replaced with other chemicals such as GenX, but these new alternatives are also suspected to have similar toxicity.” We’ve already so contaminated the Earth with it, though, that we can get it prepackaged in food before it’s even cooked, particularly in dairy products, fish, and other meat; now, “meat is the main source of human exposure” to these toxic pollutants. Of those, seafood is the worst. In a study of diets from around the world, fish and other seafood were “major contributors” of the perfluoroalkyl substances, as expected, given that everything eventually flows into the sea. Though the aquatic food chain is the “primary transfer mechanism” for these toxins into the human diet, “food stored or prepared in greaseproof packaging materials,” like microwave popcorn, may also be a source. 

    In 2019, Oral-B Glide dental floss was tested. Six out of 18 dental floss products researchers tested showed evidence of Teflon-type compounds. Did those who used those kinds of floss end up with higher levels in their bloodstream? Yes, apparently so. Higher levels of perfluorohexanesulfonic acid were found in Oral-B Glide flossers, as you can see below and at 5:28 in my video.

    There are a lot of environmental exposures in the modern world we can’t avoid, but we shouldn’t make things worse by adding them to consumer products. At least we have some power to “lower [our] personal exposure to these harmful chemicals.”

    This is the second in a three-video series on cookware. The first was Are Aluminum Pots, Bottles, and Foil Safe?, and the next is Are Melamine Dishes and Polyamide Plastic Utensils Safe?.

    What about pressure cooking? I covered that in Does Pressure Cooking Preserve Nutrients?.

    So, what is the safest way to prepare meat? See Carcinogens in Meat. 

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    Michael Greger M.D. FACLM

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  • A Look at the 5:2 Diet and the Fasting-Mimicking Diet  | NutritionFacts.org

    A Look at the 5:2 Diet and the Fasting-Mimicking Diet  | NutritionFacts.org

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    What are the effects of eating only five days a week or following a fasting-mimicking diet five days a month? 
     
    Instead of eating every other day, what if you ate five days a week and fasted for the other two? As I discuss in my video The 5:2 Diet and the Fasting-Mimicking Diet Put to the Test, the available data are similar to that of alternate-day fasting: About a dozen pounds of weight loss was reported in overweight men and also reported in overweight women over six months, with no difference found between participants on the 5:2 intermittent fasting regimen and those on a continuous 500-calories-a-day restriction. The largest trial to date found an 18-pound weight loss within six months in the 5:2 group, which isn’t significantly different from the 20 pounds lost in the continuous calorie restriction group. Weight maintenance over the subsequent six months was also found to be no different.
     
    Though feelings of hunger may be more pronounced on the 5:2 pattern than on an equivalent level of daily calorie cutting, it does not seem to lead to overeating on non-fasting days. One might expect going two days without food may negatively impact mood, but no such adverse impact was noted for those fully fasting on zero calories or sticking to just two packets of oatmeal on each of the “fasting” days. (The oatmeal provides about 500 calories a day.) Like alternate-day fasting, the 5:2 fasting pattern appeared to have inconsistent effects on cognition and on preserving lean mass, and it also failed to live up to the “popular notion” that intermittent fasting would be “easier” to adhere to than daily calorie restriction. 
     
    Compared to those in the continuous-restriction control group, fewer subjects in the 5:2 pattern group expressed interest in continuing their diet after the study was over. This was attributed to quality-of-life issues, with 5:2 fasting participants citing headaches, lack of energy, and difficulty fitting the fasting days into their weekly routine. However, as you can see below and at 1:53 in my video, there has yet to be a single 5:2 diet study showing elevated LDL cholesterol compared with continuous calorie restriction at six months. Nor has it been shown for a year. This offers a potential advantage over alternate-day regimens. 

    Instead of 5:2, what about 25:5, spending five consecutive days a month on a “fasting-mimicking diet” (FMD)? Longevity researcher Valter Longo designed a five-day meal plan to try to simulate the metabolic effects of fasting by being low in protein, sugars, and calories with zero animal protein and zero animal fat. By making the diet plant-based, he hoped to lower the level of the cancer-promoting growth hormone IGF-1. He indeed accomplished this goal, along with a drop in markers of inflammation, after three cycles of his five-days-a-month program, as you can see below and at 2:33 in my video. 

    One hundred men and women were randomized to consume his fasting-mimicking diet for five consecutive days per month or maintain their regular diet the whole time. As you can see in the graph below and at 2:47 in my video, after three months, the FMD group was down about six pounds compared to the control group, with significant drops in body fat and waist circumference, accompanied by a drop in blood pressure. 

    Those who were the worst off accrued the most dramatic benefits, as seen in the graph below and at 3:04 in my video. What’s even wilder is that three further months after completion, some of the benefits appeared to persist, suggesting the effects “may last for several months.” It’s unclear, though, if those randomized to the FMD group used it as an opportunity to make positive lifestyle changes that helped maintain some of the weight loss. 


    Dr. Longo created a company to market his meal plan commercially, but, to his credit, says “he does not receive a salary or a consulting fee from the company…and will donate 100% of his shares to charity.” The whole diet appears to be mostly dehydrated soup mixes, herbal teas like hibiscus and chamomile, kale chips, nut-based energy bars, an algae-based DHA supplement, and a multivitamin dusted with vegetable powder. Why spend 50 dollars a day on a few processed snacks when you could instead eat a few hundred calories a day of real vegetables? 
     
    How interesting was that? All-you-can-eat above-ground vegetables for five days would have the same low amount of protein, sugars, and calories with zero animal protein or animal fat. But we’ll probably never know if it works as well, better, or worse because it’s hard to imagine such a study ever getting done without the financial incentive. 

    To learn more about IGF-1, see my video Flashback Friday: Animal Protein Compared to Cigarette Smoking.
     
    In this series on fasting, I’ve covered several topics, including the basics of calories and weight loss, water-only fasting, and the types of alternate-day fasting, see them all in the related videos below. 
     
    I close out the series with videos on time-restricted eating: Time-Restricted Eating Put to the Test and The Benefits of Early Time-Restricted Eating. 
     
    If you want all of the videos in one place, I’ve done three webinars on fasting—Intermittent Fasting, Fasting for Disease Reversal, and Fasting and Cancer—and they’re all available for download now. 

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    Michael Greger M.D. FACLM

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  • The Safety of Keto Diets  | NutritionFacts.org

    The Safety of Keto Diets  | NutritionFacts.org

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    What are the effects of ketogenic diets on nutrient sufficiency, gut flora, and heart disease risk? 

    Given the decades of experience using ketogenic diets to treat certain cases of pediatric epilepsy, a body of safety data has accumulated. Nutrient deficiencies would seem to be the obvious issue. Inadequate intake of 17 micronutrients, vitamins, and minerals has been documented in those on strict ketogenic diets, as you can see in the graph below and at 0:14 in my video Are Keto Diets Safe?. 

    Dieting is a particularly important time to make sure you’re meeting all of your essential nutrient requirements, since you may be taking in less food. Ketogenic diets tend to be so nutritionally vacuous that one assessment estimated that you’d have to eat more than 37,000 calories a day to get a sufficient daily intake of all essential vitamins and minerals, as you can see in the graph below and at 0:39 in my video. 


    That is one of the advantages of more plant-based approaches. As the editor-in-chief of the Journal of the American Dietetic Association put it, “What could be more nutrient-dense than a vegetarian diet?” Choosing a healthy diet may be easier than eating more than 37,000 daily calories, which is like putting 50 sticks of butter in your morning coffee. 
     
    We aren’t just talking about not reaching your daily allowances either. Children have gotten scurvy on ketogenic diets, and some have even died from selenium deficiency, which can cause sudden cardiac death. The vitamin and mineral deficiencies can be solved with supplements, but what about the paucity of prebiotics, the dozens of types of fiber, and resistant starches found concentrated in whole grains and beans that you’d miss out on? 
     
    Not surprisingly, constipation is very common on keto diets. As I’ve reviewed before, starving our microbial self of prebiotics can have a whole array of negative consequences. Ketogenic diets have been shown to “reduce the species richness and diversity of intestinal microbiota,” our gut flora. Microbiome changes can be detected within 24 hours of switching to a high-fat, low-fiber diet. A lack of fiber starves our good gut bacteria. We used to think that dietary fat itself was nearly all absorbed in the small intestine, but based on studies using radioactive tracers, we now know that about 7 percent of the saturated fat in a fat-rich meal can make it down to the colon. This may result in “detrimental changes” in our gut microbiome, as well as weight gain, increased leaky gut, and pro-inflammatory changes. For example, there may be a drop in beneficial Bifidobacteria and a decrease in overall short-chain fatty acid production, both of which would be expected to increase the risk of gastrointestinal disorders. 
     
    Striking at the heart of the matter, what might all of that saturated fat be doing to our heart? If you look at low-carbohydrate diets and all-cause mortality, those who eat lower-carb diets suffer “a significantly higher risk of all-cause mortality,” meaning they live, on average, significantly shorter lives. However, from a heart-disease perspective, it matters if it’s animal fat or plant fat. Based on the famous Harvard cohorts, eating more of an animal-based, low-carb diet was associated with higher death rates from cardiovascular disease and a 50 percent higher risk of dying from a heart attack or stroke, but no such association was found for lower-carb diets based on plant sources.  
     
    And it wasn’t just Harvard. Other researchers have also found that “low-carbohydrate dietary patterns favoring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favored plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain bread, were associated with lower mortality…” 
     
    Cholesterol production in the body is directly correlated to body weight, as you can see in the graph below and at 3:50 in my video. 

    Every pound of weight loss by nearly any means is associated with about a one-point drop in cholesterol levels in the blood. But if we put people on very-low-carb ketogenic diets, the beneficial effect on LDL bad cholesterol is blunted or even completely neutralized. Counterbalancing changes in LDL or HDL (what we used to think of as good cholesterol) are not considered sufficient to offset this risk. You don’t have to wait until cholesterol builds up in your arteries to have adverse effects either; within three hours of eating a meal high in saturated fat, you can see a significant impairment of artery function. Even with a dozen pounds of weight loss, artery function worsens on a ketogenic diet instead of getting better, which appears to be the case with low-carb diets in general.  

    For more on keto diets, check out my video series here. 

    And, to learn more about your microbiome, see the related videos below.

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    Michael Greger M.D. FACLM

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  • Keto Diet to Effectively Fight Cancer?  | NutritionFacts.org

    Keto Diet to Effectively Fight Cancer?  | NutritionFacts.org

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    What does the science say about the clinical use of ketogenic diets for epilepsy and cancer? 

    Blood sugar, also known as blood glucose, is the universal go-to fuel for the cells throughout our bodies. Our brain burns through a quarter pound of sugar a day because “glucose is the preferred metabolic fuel.” We can break down proteins and make glucose from scratch, but most comes from our diet in the form of sugars and starches. If we stop eating carbohydrates (or stop eating altogether), most of our cells switch over to burning fat. Fat has difficulty getting through the blood-brain barrier, though, and our brain has a constant, massive need for fuel. Just that one organ accounts for up to half of our energy needs. Without it, the lights go out…permanently. 

    To make that much sugar from scratch, our body would need to break down about half a pound of protein a day. That means we’d cannibalize ourselves to death within two weeks, but people can fast for months. What’s going on? The answer to the puzzle was discovered in 1967. Harvard researchers famously stuck catheters into the brains of obese subjects who had been fasting for more than a month and discovered that ketones had replaced glucose as the preferred fuel for the brain. Our liver can turn fat into ketones, which can then breach the blood-brain barrier and sustain our brain if we aren’t getting enough carbohydrates. Switching fuels has such an effect on brain activity that it has been used to treat epilepsy since antiquity. 

    In fact, the prescription of fasting for the treatment of epileptic seizures dates back to Hippocrates. In the Bible, even Jesus seems to have concurred. To this day, it’s unclear why switching from blood sugar to ketones as a primary fuel source has such a dampening effect on brain overactivity. How long can one fast? To prolong the fasting therapy, in 1921, a distinguished physician scientist at the Mayo Clinic suggested trying what he called “ketogenic diets,” high-fat diets designed to be so deficient in carbohydrates that they could effectively mimic the fasting state. “Remarkable improvement” was noted the first time it was put to the test, efficacy that was later confirmed in randomized, controlled trials. Ketogenic diets started to fall out of favor in 1938 with the discovery of the anti-seizure drug that would become known as Dilantin, but they’re still being used today as a third- or fourth-line treatment for drug-refractory epilepsy in children. 

    Oddly, the success of ketogenic diets against pediatric epilepsy seems to get conflated by “keto diet” proponents into suggesting a ketogenic diet is beneficial for everyone. Know what else sometimes works for intractable epilepsy? Brain surgery, but I don’t hear people clamoring to get their skulls sawed open. Since when do medical therapies translate into healthy lifestyle choices? Scrambling brain activity with electroshock therapy can be helpful in some cases of major depression, so should we get out the electrodes? Ketogenic diets are also being tested to see if they can slow the growth of certain brain tumors. Even if they work, you know what else can help slow cancer growth? Chemotherapy. So why go keto when you can just go chemo? 

    Promoters of ketogenic diets for cancer are paid by so-called ketone technology companies that offer to send you salted caramel bone broth powder for a hundred bucks a pound or companies that market ketogenic meals and report “extraordinary” anecdotal responses in some cancer patients. But more concrete evidence is simply lacking, and even the theoretical underpinnings may be questionable. A common refrain is that “cancer feeds on sugar.” But all cells feed on sugar. Advocating ketogenic diets for cancer is like saying Hitler breathed air so we should boycott oxygen. 

    Cancer can feed on ketones, too. Ketones have been found to fuel human breast cancer growth and drive metastases in an experimental model, more than doubling tumor growth. Some have even speculated that this may be why breast cancer often metastasizes to the liver, the main site of ketone production. As you can see below and at 4:59 in my video Is Keto an Effective Cancer-Fighting Diet?, if you drip ketones directly onto breast cancer cells in a petri dish, the genes that get turned on and off make for much more aggressive cancer, associated with significantly lower five-year survival in breast cancer patients, as you can see in the following graph and at 5:05 in my video. Researchers are even considering designing ketone-blocking drugs to prevent further cancer growth by halting ketone production.  

    Let’s also think about what eating a ketogenic diet might entail. High animal fat intake may increase the mortality risk among breast cancer survivors and potentially play a role in the development of breast cancer in the first place through oxidative stress, hormone disruption, or inflammation. This applies to men, too. “A strong association” has been found “between saturated fat intake and prostate cancer progression and survival.” Those in the top third of consumption of these kinds of fat-rich animal foods appeared to triple their risk of dying from prostate cancer. This isn’t necessarily fat in general either. No difference has been found in breast cancer death rates based on total fat intake. However saturated fat intake specifically may negatively impact breast cancer survival, increasing the risk of dying from it by 50 percent. There’s a reason the official American Cancer Society and American Society of Clinical Oncology Breast Cancer Survivorship Care Guideline recommend a dietary pattern for breast cancer patients that’s essentially the opposite of a ketogenic diet. It calls for a diet that’s “high in vegetables, fruits, whole grains, and legumes [beans, split peas, chickpeas, and lentils]; low in saturated fats; and limited in alcohol consumption.” 

    “To date, not a single clinical study has shown a measurable benefit from a ketogenic diet in any human cancer.” There are currently at least a dozen trials underway, however, and the hope is that at least some cancer types will respond. Still, even then, that wouldn’t serve as a basis for recommending ketogenic diets for the general population any more than recommending everyone get radiation, surgery, and chemo just for kicks. 

    “Keto” has been the most-searched keyword on NutritionFacts.org for months, and I didn’t have much specific to offer…until now. Check out my other videos on the topic in related videos below. 

     For an overview of my cancer work, watch How Not to Die from Cancer. 

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    Michael Greger M.D. FACLM

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