The Antioxidant Myth

December 30, 2017

cure-all pomegranate snake oilThe truth about antioxidant-rich plant extracts and supplements is that they simply do not work. The most powerful way to boost your free-radical fighting power is by making  one simple change to your diet to activate your body’s own natural internal antioxidant, glutathione. Find out why products like turmeric and Pom Wonderful are not worth your hard-earned money. Read my full article on Psychology Today.


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Cooling Brain Inflammation Naturally with Food

December 30, 2017

surprised man with inflamed headPsychiatric disorders like depression, bipolar disorder and psychosis are strongly tied to inflammation. Psychiatric medications are not designed to fight inflammation, but did you know there are two changes you can make to your diet that will naturally reduce inflammation in your brain and body? Learn how to heal brain inflammation from the inside out in my article on Psychology Today.


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Ketosis for Psychosis

September 30, 2017

ketosis for psychosisWhat happened when two adults with severe mood and psychotic symptoms for years embarked on a ketogenic diet for weight loss? Yes, they lost weight, but what ELSE happened? Harvard psychiatrist Dr. Chris Palmer shared the inspiring stories of two people in his practice who experienced long overdue relief that even the strongest antipsychotic and mood stabilizing medications could not provide. Read the remarkable results in my newest post on Psychology Today.

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Low Brain Cholesterol—Statins, Vegan Diets and Mental Health

September 19, 2017

low brain cholesterolWhere do you find the highest concentration of cholesterol in your whole body? In your BRAIN. The brain is cholesterol-rich on purpose—because it needs large amounts of cholesterol to function properly. So, what does that mean for the growing number of people choosing naturally cholesterol-free plant-based diets? And what about the 15 million Americans who take statin medications like Lipitor to lower their cholesterol levels?

People who are trying to lower their cholesterol levels are worried about heart health. But how does lowering cholesterol affect mental health?

For answers to all of these questions and more, continue reading my article on Psychology Today. 

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Your Brain on Plants: Micronutrients and Mental Health

September 5, 2017

your brain on plants

Plant-Based Diets, Micronutrients and Mental Health

Do vegetarian and vegan diets contain the micronutrients our brains need to function properly? Or do they put people at risk for serious deficiencies that increase the likelihood of developing psychiatric disorders?

In my last post, Food Fights: Are Vegan Diets Healthier for the Brain? we compared big-picture health effects of plant-based diets to meat-based diets, and discovered more similarities between them than many might have expected. Today, we go micro! We will explore each nutrient’s function in the brain, and the psychiatric symptoms that can develop if we don’t get enough of each one. I created this comprehensive summary of the science to be a resource for everyone, regardless of chosen diet, so that we may all improve our understanding of how to help our brains function at their absolute best.

You will notice that certain essential nutrients are missing. This is because those nutrients are generally easy to obtain from both plant-based and omnivorous diets. I also chose to reserve coverage of deficiency testing and supplementation for future posts, as complete discussion of any one of these fascinating nutrients would have been pages long (and believe me, I was going there…)

Before we get started, a few definitions:

  • Vegan = completely avoids all animal foods, including dairy and eggs
  • Vegetarian = avoids all animal foods except for dairy products and/or eggs
  • Omnivore = eats plants and animals (may or may not eat eggs or dairy); pescatarians are included in this category
  • Meat = the meat of any animal—red meat, poultry, seafood, etc.
  • Animal foods = meat, eggs, dairy products

Ready? Onward!

Plant Micronutrients

Most people think of fruits and vegetables as teeming with the vitamins, minerals, and powerful antioxidants we need to live and thrive. It is true that many plant foods are rich in many of these substances, but just because a food contains a particular nutrient doesn’t mean we can access it. Unfortunately, plant nutrients often suffer from low “bioavailability”—which means that they are hard for us to extract, absorb, and utilize. Below I summarize the most important potential brain nutrient deficiencies that ALL plant-eaters—vegans, vegetarians and omnivores— need to be aware of, as well as key deficiency risks unique to vegans and vegetarians.

Fat-Soluble Vitamins (A, D, K2)

Vegan diets increase risk for certain fat-soluble vitamin deficiencies. Low-fat vegan diets further increase risk for these deficiencies, because sufficient fat must be eaten with every meal in order to absorb these vitamins from food.

Vitamin A

Contrary to popular belief, plant foods are lousy sources of vitamin A. In fact, they contain no vitamin A at all! Instead, they contain carotenoids, which we must then convert into retinol, the form of vitamin A our bodies can use. This is 12 to 24 times more difficult than obtaining retinol from animal foods. This helps to explain why childhood blindness due to vitamin A deficiency is rampant in dozens of developing countries, particularly in Africa and South-East Asia:

“Poor bioavailability plays a predominant role in the development of [Vitamin A deficiency] among communities that mainly rely on plant-based foods.”  1)J Health Popul Nutr 2013;31(4): 413–423

Fortunately, vitamin A deficiency in the U.S. and other developed countries is very rare, due to the abundance of animal foods and because many processed foods are fortified. Although vitamin A is important to many aspects of brain function including vision, learning, and memory, I’m not aware of any human studies demonstrating that vitamin A deficiency causes psychiatric disorders.

Vitamin D

Brain gets vitamin D from the sunThe form of vitamin D our bodies need is vitamin D3 (cholecalciferol). We can make Vitamin D3 from sunshine or obtain it from animal foods.

The form of vitamin D found in plant foods is vitamin D2 (ergocalciferol). Our bodies can convert some D2 to D3, but D2 is less potent, doesn’t last as long in the bloodstream, and may be harder to store in our body fat for rainy days and dark winters.2)Tripkovic et al 2012 Am J Clin Nutr 95(6): 1357–1364, Wilson LR et al 2017 Proc Nutr Soc 1-8 If we spend enough time in the sun, we don’t need to obtain any vitamin D from our diet at all, yet many people (regardless of chosen diet) are deficient. Most studies have found that vegans have lower blood levels of vitamin D3 and are more likely to drop to deficient levels during winter months than omnivores.3)Crowe et al 2010 Public Health Nutrition 14(2): 340–346; Wilson LR et al 2017 Proc Nutr Soc 1-8

Vitamin D3 is important in brain growth and development, regulates calcium levels within the brain, helps protect brain cells from damaging oxidation, and supports the health of the hippocampus (the brain’s memory center). Lower levels of vitamin D3 are associated with an increased risk for schizophrenia, autism, depression, and dementia.4)Eyles et al 2013 Front Neuroendocrinol 34(1):47-64 But that doesn’t mean deficiency causes those conditions. Can D3 supplements help with psychiatric disorders? I did not find any clinical trials studying D3 supplementation and psychosis or dementia, and found only one study showing slight improvement in depression symptoms.5)Sepehrmanesh et al 2016 J Nutr 146:243–8 However, several recent studies of Vitamin D3 supplementation have shown promising improvements in autism symptoms.6)Feng et al 2017 Nutr Neurosci 20(5):284-290

Vitamin K2

When most people think of vitamin K they think of vitamin K1, which is abundant in many plant foods, but vitamin K2 is just as important and often overlooked. Vitamin K2 is confusing because it comes in many forms, but the essential form we need is called MK-4, which only exists in animal foods. In the brain, MK-4 is required to build critical cell membrane components called sphingolipids, as well as to support the overall health and function of brain cells.7)Ferland 2012 Biofactors 38(2):151-7 It stands to reason that MK-4 deficiency could cause mental health problems, but I’m not aware of any human studies exploring the potential connection between K2 deficiency and any psychiatric disorder (K2 is poorly studied in general).

The body can convert a little bit of K1 into MK-4 (vitamin K2), but not nearly enough to fully meet our needs. Therefore, savvy vegans turn to natto (fermented soy), which contains a bacterial form of vitamin K that our bodies can turn into MK-4 a little more easily. For an excellent education on vitamin K, please see Chris Masterjohn PhD’s article The Ultimate Vitamin K2 Resource. He recommends that vegans take special supplements instead of relying solely on natto to meet their K2 requirements.

B Vitamins

Vitamin B12 (Cobalamin)

Vegan diets contain virtually no vitamin B12. Without this essential vitamin, the body cannot synthesize DNA, RNA, red blood cells, or myelin (the substance that wraps around and insulates our brain circuitry). Not surprisingly, B12 deficiency can CAUSE a whole host of serious psychiatric problems, including depression, psychosis, memory problems, mania, and changes in behavior or personality.8)Lachner et al 2012 J Neuropsychiatry Clin Neurosci 24(1):5-15

Severe, prolonged B12 deficiency is fatal. Most vegans and vegetarians are aware of this danger and either take supplements or consume fortified yeast (yeast doesn’t naturally contain any vitamin B12). Unfortunately, deficiency is still far more common than it should be, with some studies finding that as many as 86% of adults (regardless of chosen diet) are deficient. Researchers report wide ranges of values, but overall, vegetarians tend to have lower B12 levels than omnivores, and vegans on average tend to have the lowest B12 levels.9)Pawlak R et al 2014 European Journal of Clinical Nutrition 68, 541–548 Unfortunately, B12 blood levels often don’t always tell the whole story, so proper assessment requires additional tests, most commonly methylmalonic acid and total homocysteine levels.10)Stabler 2013 N Engl J Med 2013; 368:149-16 [More on the nuances of proper B12 testing and supplementation in a future post.]

Other B vitamins

Vitamin B1 (thiamin), B2 (riboflavin), B3 (niacin), B5 (pantothenic acid), B6 (pyridoxine), B7 (biotin) and B9 (folate) all work together to extract energy from food and build vital molecules. The brain is a high-energy organ, so even temporary, mild deficiencies of a single B vitamin can significantly disrupt normal brain function. All B vitamins are water-soluble, so what isn’t used is lost in the urine rather than stored in body fat. This means we need to eat good sources of B vitamins as often as several times per week in order to keep our brains functioning at their best.

All of the B vitamins except for B12 can be found in plant foods, yet some studies find that vegans are more likely to be deficient in vitamin B3 (niacin), B6 (pyridoxine).11)Schupbach R et al 2017 Eur J Nutr 56(1):283-293, Vudhivai N et al 1991 J Med Assoc Thai 74(10):465-70., and B2 (riboflavin). Riboflavin seems to be the one that vegans need to pay the most attention to, as studies have more consistently shown higher risk of deficiency of this B vitamin in vegans compared to vegetarians and omnivores.

“Riboflavin deficiency is endemic in populations who exist on diets lacking dairy products and meat.”12)Powers HJ Am J Clin Nutr 2003;77:1352–60

All three of these B vitamins can be found in plant foods, but often in smaller amounts than animal foods, so it can be challenging to obtain adequate amounts from a vegan diet unless great care is taken to include just the right mixture of foods.

Riboflavin (Vitamin B2)

Riboflavin deficiency disrupts normal serotonin metabolism and brain energy production.13)Lanska DJ 2010 Handb Clin Neurol 95:445-76. Chapter 30: Historical aspects of the major neurological vitamin deficiency disorders: the water-soluble B vitamins. Serotonin is a key neurotransmitter (brain communication chemical) that helps to regulate mood, appetite and sleep, among other things. Deficiency can cause fatigue, personality changes and general brain dysfunction.14)Kennedy DO Nutrients 2016, 8, 68

Niacin (Vitamin B3)

Niacin is also required for proper serotonin metabolism and brain energy production. Severe niacin deficiency leads to pellagra, a disease which can cause depression, psychosis, delirium and dementia. Pellagra was common over a century ago in communities living on corn-based diets. Corn happens to contain a form of niacin our bodies can’t use, AND is low in tryptophan (the amino acid needed to form serotonin) resulting in a one-two punch to serotonin activity in the brain.15)Lanska DJ 2010 Handb Clin Neurol 95:445-76. Chapter 30: Historical aspects of the major neurological vitamin deficiency disorders: the water-soluble B vitamins.

Pyridoxine (Vitamin B6)

Pyridoxine is essential for the synthesis of numerous neurotransmitters, including serotonin, dopamine, GABA, norepinephrine, and melatonin. The primary symptoms of vitamin B6 deficiency are depression, difficulty concentrating, and dementia.16)Lanska DJ 2010 Handb Clin Neurol 95:445-76. Chapter 30: Historical aspects of the major neurological vitamin deficiency disorders: the water-soluble B vitamins.

Essential Minerals


Most plant foods are quite low in iodine compared to many animal foods. Iodine is a required building block in thyroid hormone, which is critical in brain development and maintenance. Lack of iodine, particularly in early life, stunts body and brain growth. Iodine deficiency affects two BILLION people, and is the most common preventable cause of intellectual disabilities in the world.

Little is known about how simple iodine deficiency (without hypothyroidism) might affect brain function beyond infancy, although a recent Polish study found a correlation between lower iodine levels and certain symptoms of autism.17)Blazewicz et al 2016 Journal of Trace Elements in Medicine and Biology 34; 32–37. Two randomized placebo-controlled clinical trials found that replenishing iodine to normal levels in schoolchildren improved their cognitive function.18)Redman K et al 2016 Critical Reviews in Food Science and Nutrition 56:2695-2713

Fortunately, iodine deficiency in the United States is uncommon due to the widespread use of iodized salt. Vegans, on average, have lower iodine levels than vegetarians, and are more likely to meet criteria for iodine deficiency on paper, but nevertheless appear to have normal thyroid function.19)Leung et al 2011 J Clin Endocrinol Metab 96(8): E1303–E1307.


Many plant foods are lower in iron than animal foods, and to make matters worse, plants contain a form of iron that is far more difficult to absorb than heme iron, the form found in animal foods.20)Miret S et al Annu. Rev. Nutr. 2003. 23:283–301 Most vegans and vegetarians have about the same amount of iron in their blood as omnivores do, but their total body iron stores (how much they have in reserve) do tend to be lower.21)Gibson RS et aAm J Clin Nutr 2014;100(suppl):459S–68S

brain pumping ironWhen people think of iron deficiency, they think of anemia (lower numbers of red blood cells in the circulation), but the truth is that the brain needs iron just as much as red blood cells do. Iron is required for neurotransmitter production (serotonin, dopamine and norepinephrine), generation of brain energy, hippocampal function (memory!), cell signaling, and infant brain development (which means that expectant and breastfeeding mothers must take in plenty of iron). People with iron deficiency may be more likely to have psychiatric problems such as depression and schizophrenia,22)Kim and Wessling-Resnick 2014 Journal of Nutritional Biochemistry 25: 1101–1107 but we don’t yet have studies that can tell us whether iron deficiency alone can cause these conditions.


Plant foods are far lower in zinc than animal foods. Zinc deficiency is much more common among vegans than iron deficiency, and yet gets far less attention, perhaps because it is difficult to accurately measure zinc levels in the body. A 2017 Swiss study found that 47% of vegans had inadequate zinc levels compared to only 10% of omnivores.23)Schüpbach R et al 2017 Eur J Nutr 56 (1): 283–293. The brain requires zinc for serotonin synthesis, vitamin B6 activation, and cell signaling.24)Villagomez and Ramtekkar 2014. Children 1: 261-279. People with low zinc levels are more likely to be depressed, but more importantly, some clinical trials show that combining zinc supplements with antidepressants improves outcomes.25)Gronli O et al 2013 PLoS One 8(12):e82793 and Lomagno K et al 2014 Nutrients 6(11): 5117-5141 There’s even been one randomized controlled trial demonstrating that zinc supplements alone can reduce severity of depression symptoms.26)Solati Z et al 2015 Nutr Neurosci 18(4):162-8.

Some studies suggest that zinc deficiency may play a role in childhood ADHD symptoms, but the jury is still out.27)Ghanizadeh and Berk 2013 European Journal of Clinical Nutrition 67: 122–124 Older people with zinc deficiency are more likely to have poor overall mental health, but no causal relationship between the two has been established.

Our bodies can store iron, but we have no good way to store zinc, so we must eat high quality sources of zinc on a regular basis, or take supplements. The challenge for those choosing a vegan diet is that the plant foods richest in zinc also happen to contain compounds which interfere with zinc absorption—which brings us to the fascinating topic of antinutrients!

Plant Antinutrients and Mineral Deficiencies

Phytic Acid

The grains, beans, nuts and seeds that vegan diets rely upon for protein are technically all seeds. For example, grains are the seeds of grasses. Seeds are higher in protein than most other plant parts, but they are unfortunately also high in phytic acid, a mineral magnet that interferes with our ability to absorb iron, zinc, calcium and magnesium. Seeds use this clever molecule to hold on to precious minerals so they can’t be washed away in the soil while waiting to sprout. Unfortunately, seeds don’t just selfishly hoard their own minerals. Phytic acid also steals minerals from other unsuspecting foods you may eat with your seeds, making it more difficult for you to extract minerals from everything you eat. Take a look at how much black beans (a legume) and corn (a grain) interfere with zinc absorption!

phytic acid interference with zinc absorption

This study illustrates the significant impact of phytic acid on zinc absorption. The graph indicates the rate of zinc absorption from oysters alone, and oysters when eaten with black beans or corn tortillas. (Solomons et al. 1979 J Lab Clin Med 94(2):335-343)


A wide variety of plant foods contain goitrogens which interfere with iodine metabolism and thyroid hormone production. Examples include soy, millet, cassava, rutabaga, and the entire cruciferous vegetable family, including kale and broccoli. [I have a whole post dedicated to this topic if you are curious to learn more.]


Oxalates are corrosive compounds which naturally occur in plant foods and interfere with iron, calcium and magnesium absorption. Plants use oxalates to regulate their own internal mineral content and help defend against predators.28)Franceschi and Nakata 2005 Annu Rev Plant Biol 56:41–71 Foods rich in oxalates include cocoa, beets, sesame seeds, rhubarb, sweet potato, coriander, currants, and spinach. In fact, thanks to oxalates, virtually none of the iron present in spinach makes it into Popeye’s body.29)Noonan SC et al 1999 8(1) 64-74 If only steak came in a can…


Tannins are darkly-pigmented astringent compounds which naturally occur in plant foods and interfere with iron absorption.30)Clemens S 2014 Plant Science 225 p 52-57. Tannins are found in a wide variety of foods including legumes, nuts, cocoa, wine, tea, berries, pomegranates, and many other fruits.

Of course, most omnivores eat plenty of grains, beans, high-tannin, high-oxalate and high-goitrogen plant foods too, which may help to explain why so many omnivores are also deficient in key minerals.

Essential Fatty Acids: DHA and EPA


Vegan diets contain absolutely no DHA or EPA, the forms of essential omega-3 fatty acids required for brain and immune system function (and vegetarian diets contain only small amounts from eggs and dairy). The brain is extremely rich in DHA, which is required to make myelin (the material that wraps around nerve cells, insulating brain circuits), and to keep cell membranes fluid and flexible enough to pass neurotransmitters back and forth. DHA is critical in the formation of healthy synapses (connections between brain cells), therefore infant brains require lots of DHA to develop properly. In short, DHA plays a “unique and indispensable role” in the “cohesive, organized neural signaling essential for higher intelligence.”31)Dyall SC 2015 Frontiers in Aging Neuroscience 7(52)

omega 3 levels in vegansIn comparison to omnivores, EPA and DHA levels can be about 30% lower in vegetarians and more than 50% lower in vegans.32)Rosell S et al 2005 Am J Clin Nutr 82(2):327-334 This is primarily because the form of omega-3 (ALA) found in plant foods (flax, chia, walnut, etc.) is very difficult for the body to convert into the DHA our brains need. At best, women convert only about 9% of the ALA they consume into DHA, whereas men convert a dismal 0-4%.33)Arterburn 2006

The only veg-friendly supplements on the market that contain any EPA or DHA are those derived from algae. [Plant-sourced omega-3 supplements such as those from flax or chia contain ALA only]. Therefore, I strongly recommend that every vegan and vegetarian take an algae-sourced omega-3 supplement. EPA and DHA are hard to come by even in most omnivorous diets, because the foods that naturally contain them (oily fish, pastured animal fats/organs) are ones that people don’t eat much of these days, so even omnivores may need to supplement.

There have been numerous studies demonstrating that people with lower levels of omega-3 fatty acids in their bodies are more likely to suffer from ADHD, depression, bipolar disorder, and schizophrenia, but these are just associations. What’s more important is that omega-3 supplements rich in EPA seem to have positive effects on people with major depression, bipolar disorder, and those at risk for psychotic disorders.34)Messamore and McNamara Lipids in Health and Disease 2016; 15:25

It is unclear why EPA seems to work better as a supplement than DHA, but it clearly does.35)Sublette et al 2011 J Clin Psychiatry 72(12): 1577–1584 At the recent International Society for Nutritional Psychiatry research meeting, I spoke with leading fatty acid researchers Michael Crawford PhD and Alex Richardson PhD about this, and they suggested that EPA’s superior effectiveness in short-term studies is likely due to its fast-acting anti-inflammatory properties. They emphasized that DHA remains vitally important long-term to brain structure and function despite its weaker performance in clinical trials. Some suggest that the effects of DHA supplements may take years to notice, so most clinical trials are far too short to demonstrate its importance.

[Note: just as important as improving EPA and DHA intake is reducing the amount of omega-6 fatty acids in the diet. Please see my previous post or my Fats Page for details.]

Do Vegans Get Enough Protein?

Contrary to popular belief, there is no evidence that vegans suffer from true protein deficiency, despite the fact that plant proteins are more challenging to digest and absorb than animal proteins.36)Tome D 2012 Br J Nutr 108 Suppl 2:S222-9 Fortunately, it appears that most people in the developed world meet their daily minimum requirement for protein without even trying. That doesn’t mean that some of us aren’t walking around with less than optimal protein intake, it’s just that we don’t have a shared understanding of what the symptoms of mild protein deficiency are or what our optimal daily protein intake should be.37)Fukagawa NK 2014 Am J Clin Nutr 99(4):761-2 This is an area of great controversy in the nutrition nerd networks (of which I’m a proud card-carrying member). Please see my Protein Page for more information.

Do Vegans Have Low Brain Cholesterol?

We are often told that one advantage of a vegan diet is that all plant foods are naturally 100% cholesterol-free. Yet the brain (and indeed, every cell in the human body) requires cholesterol to function properly.

the brain makes its own cholesterolThe human brain is loaded with cholesterol—on purpose. Although the brain represents only 2% of total body weight, it contains 20% of the body’s cholesterol. Cholesterol is required for brain cell membrane structure and function, and is a vital component of myelin (brain cell insulation). This leads some to worry that vegans are at risk for low brain cholesterol, but is there really any cause for alarm?

Even though vegan diets contain zero grams of cholesterol, there is good reason to believe that vegans might not suffer from low brain cholesterol after all. This is because the brain does not obtain its cholesterol from the foods we eat! Cholesterol is too big and bulky to cross the blood-brain barrier—so the brain makes all of its own cholesterol on site. Cholesterol can be manufactured out of anything—carbohydrate, protein, or fat—so regardless of what we eat, we can always make plenty of cholesterol. Case in point: plenty of vegans have “high cholesterol” despite eating zero grams of cholesterol per day–if you don’t believe me, simply google “vegan high cholesterol” or see this interesting case study.

There are some (epidemiological) studies weakly suggesting that people with lower total cholesterol levels may be more likely to have depression and suicidal ideation,38)Wu S et al 2016 J Psychiatry Neurosci 41(1):56-69 but these cannot show a cause and effect relationship. And again, just because blood cholesterol may be low doesn’t mean that brain cholesterol is low. Unfortunately there is currently no way to directly measure brain cholesterol content in living human beings.39)Hughes et al 2013 J Alzheimers Dis 33(4):891–911 Furthermore, there is no consensus about what constitutes a low LDL level in the first place. In other words, we aren’t sure how low is too low. 40)Persons and Fiedorowicz 2016 J Affect Disord 206:55-67 For more information, please see my Cholesterol Page.

So, Do Plant-based Diets Increase Risk for Mental Health Problems?

Yes, unfortunately they do.

Taking all of the above information in, you may have noticed two interesting things:

  1. Most brain-essential nutrients are easier to find in animal foods, and in some cases are ONLY found in animal foods.
  2. A staggering variety of plant foods interfere with our ability to process vital nutrients, making them harder to absorb, utilize and/or store.

If you were a curious alien who had just landed on planet Earth and were reviewing the facts about human nutrition for the first time (this would absolutely be the very first thing I would do upon arriving on a foreign planet), you would logically conclude that consuming animal foods is critical to human health. You may even go so far as to wonder—as I do—whether we would be better off not eating any plants at all! While we don’t have the clinical studies to prove it, my suspicion, after having studied this topic for nearly ten years now, is that the more plants we eat, the harder it is for our brains (and bodies) to operate at the top of their game.

Why Doesn’t Everyone Just Eat Animals?

If we were Spock-like beings, unencumbered by emotion, we would probably all see the logic in eating animals for our own health. However, there are many reasons for choosing a plant-based diet that have nothing to do with human health goals.

trends in vegan and vegetarian diets in college students

Approximately four percent of my Smith College student patients report eating a vegan diet (that’s about twice the national average compared to other college campuses across the country), and the great majority of them cite compassion for animals or environmental concerns—not health—as their primary motivation.

It is my job as their psychiatrist to educate my students about the mental health risks of eating a plant-based diet, and to make the responsible, science-based recommendation that they reintroduce some animal foods into their menus. How many vegan students have I convinced to change their diets in the past four years? ZERO.

So, it then becomes my job to educate them about how to optimize the quality of their plant-based diet through proper supplementation and avoidance of high-risk foods such as refined carbohydrates and processed seed oils (see previous post).

Food is incredibly personal—more personal and socially charged, perhaps, than religion or politics. We each make decisions based on our own priorities, and should respect each other’s choices. I just want people to have the information they need to make informed decisions.

Meat Quality and the Environment

While it would be psychologically simpler and more comfortable if we didn’t need animal foods, it appears to me that animal foods are an important part of a healthy diet. In a perfect world, we would all eat only the highest quality animals—either wild or humanely/naturally-raised. I am fortunate to belong to a local meat CSA where animals are raised naturally and humanely, but not everyone has that luxury, of course, and when traveling or eating out, we all lose some control over our options.

I am not qualified to comment on the environmental impact of animal-based diets, as I haven’t personally studied the science, but there are many others who have. It appears that the questions of whether plant-based diets are the most sustainable for our species and healthiest for our planet are at least open to debate, and that if animals are raised naturally, there may even be certain environmental benefits. It seems there are no easy answers, so we each have to wrestle with these dilemmas in our own ways. My goal is not to answer these questions or solve the larger problems that population growth and human culture creates, but to understand what foods we need to be healthy. Those of you currently eating a vegan diet who wish you could ethically add some animal food to your menu for health reasons may find this article about oysters interesting.

Are Carefully-supplemented Vegan Diets Perfectly Healthy?

I don’t think anyone knows the answer to this question. My personal take on supplements is that the human body is best-adapted to obtaining nutrients from whole foods, and we are probably healthiest when we use that strategy. We may not be well-adapted to processing isolated nutrients in pill form once a day, but supplements are a critically important strategy for those who choose plant-based diets, don’t have access to high-quality animal foods (much of the developing world), or have health issues that interfere with normal digestion and absorption of nutrients from whole foods. I will be addressing the issue of supplementation in more detail in future posts.

The Bottom Line: The Brain Needs Meat

There are many valid, respectable, understandable reasons to choose a vegan diet, but as far as I can tell, better health is not one of them. That being said, given everything I have learned about how plants operate within the human body, the only meat-eaters who may be able to claim a “healthier than thou” stance in comparison to plant-eaters are the ones who don’t eat any plants at all. But this is not a contest—it is a search for understanding. My study of nutrition has convinced me that red meat, poultry and seafood are the most nutritious foods for the human brain (and body). So, if you’re only avoiding meat because you think you’ll be healthier without it, I am here to tell you that I find no evidence that eating meat is risky. In fact, everything I’ve read indicates that NOT eating meat is risky. So, enjoy that juicy, nutrient-dense, antinutrient-free steak, duck, salmon or oyster. Doctor’s orders?

In the near future, I’ll be writing about which tests are best to help you figure out if you have any micronutrient deficiencies, and how to bring your levels back to normal with foods or supplements. To be notified of new posts as they become available, simply sign up below.

Come hear my new presentation entitled: Plants vs. Animals: Bring It On! at LowCarbUSA West Palm Beach, Florida from Fri Jan 19 through Sun Jan 21, 2018. See the full line of speakers and register here. Space is limited for this wonderful conference which is designed to maximize interaction between audience and presenters. Hope to see you there!

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Food Fights: Are Vegan Diets Healthier for the Brain?

July 28, 2017

How do vegan diets affect the brainHow brain-healthy is YOUR diet?

We think a lot about how plant-based diets and animal-based affect our hearts, our blood sugar levels, or our risk for cancer, but how do our dietary choices affect our brains? What do we actually know about vegan diets and mental health? As a psychiatrist who specializes in nutrition, this question is near and dear to my heart, and one that richly deserves our attention.

Those of you familiar with my work know that I eat a highly unorthodox mostly-meat, low-plant diet, but that was not always the case. In my 20s and 30s I ate a low-meat, low-fat, high-plant diet because that’s what I was told was best for me. In my early 40s, numerous mysterious symptoms descended upon me—chronic fatigue, fibromyalgia, IBS, migraines, etc.—forcing me to experiment with my diet in hopes of finding relief. The diet that completely resolved all of those issues and more, was a high cholesterol, high-fat, low-fiber diet. Naturally, I was worried that this strange new diet would slam my arteries shut, so I began to study the science behind the headlines.

We are all doing our best with the information we have to make healthy choices. It’s just that the information we have can be really confusing and is often divisive. I’d like to challenge some assumptions on both sides of the great plant vs. animal diet debate that are often overlooked, in hopes of finding common ground and creating a foundation for meaningful dialogue. Yes, I will be making the case for meat (red meat, poultry, and/or seafood), and no, I am not funded by the meat industry. My sincere intention is to support everyone in making their diet of choice healthier by providing useful information.

My reading of nutrition science over the past ten years has led me to conclude that vegan diets are hard on the human body… but I will argue below that omnivorous diets can be hard on the body, too.

The plant-based foods movement

Vegan diets contain no animal foods whatsoever, and are therefore naturally cholesterol-free and typically low in saturated fat. An ever-growing number of influential individuals and powerful institutions actively promote diets rich in plant foods and low in animal foods—from health care professionals like physicians and dietitians to government agencies like the USDA and the World Health Organization. No wonder more and more consumers believe a vegan diet is the holy grail of human health.

This, despite the undisputed fact that un-supplemented vegan diets are nutritionally incomplete. This alone should give one pause about the merits of vegan diets. Even with supplementation, it is challenging for people who choose plant-based diets to meet their nutritional requirements using strictly whole foods. In fact, even though the plant-rich diet recommended by the USDA allows some animal foods, it is so nutritionally weak that the US Dietary Guidelines specifically recommend that EVERYONE eats refined carbohydrates like flour and cereals, because they are fortified with essential nutrients:

“Refined grains, such as white flour and products made with white flour, white rice, and de-germed cornmeal, are part of the intake recommendation because they are commonly enriched with iron and several B vitamins, including thiamin, niacin, and riboflavin…Since 1998, enriched grains also have been fortified with folic acid and are thus an important source of folic acid for women of childbearing potential…The 2015 DGAC concluded that consumption of only whole grains with no replacement or substitution would result in nutrient shortfalls.” [Part D, chapter 1, lines 1088-1156]

The USDA recommends that grains and legumes serve as staple protein foods, despite the awkward fact that those foods are such poor sources of vital nutrients that they need to be artificially fortified…and you can’t fortify a whole food. [Dairy is arguably an exception, but we’ll get to dairy further below…and vegan diets exclude dairy products]. In contrast, red meat, poultry and seafood are naturally nutritionally dense and have been part of the human diet for nearly two million years–why not specifically recommend these as staple sources of protein?.

Are vegan diets good for the brain?

The short answer? Un-supplemented vegan diets lack key nutrients required for human cells to operate, and therefore are incompatible with human life. Of course they will cause brain malfunction, but exactly what that will look like in different individuals is hard to predict.

In my next post, Your Brain On Plants, I delve into the details of how plant-based and animal-based diets compare in terms of vitamins, minerals, protein, cholesterol, and essential fatty acids—and how those differences affect the brain and various psychiatric conditions. Even I was surprised to learn some of the things that came to light as I worked on that article. Spoiler alert: there is strong, irrefutable scientific evidence that un-supplemented and improperly-supplemented vegan diets jeopardize overall mental health. One of the most concerning things I learned in my research is that most vegans are not properly assessed for critical deficiencies and most do not supplement correctly. Whether carefully supplemented vegan diets can sustain excellent mental health is a different question altogether. I honestly don’t think anyone knows the answer. Vegan diets are a relatively new phenomenon in world history. Completely removing animal foods from the diet is a risky human experiment—although, to be fair, so is eating the standard American diet…

Eat and Let Eat

On the surface, the definitions are simple—vegan diets contain no animal products whereas omnivorous diets contain both plant and animal foods. However we can’t lump all vegan diets together, just as we can’t lump all omnivorous diets together. Not all vegans eat the same way, just as not all omnivores eat the same way.

To fairly and objectively evaluate the health effects of these dietary patterns, it is not enough to sit on our respective mountaintops and make sweeping judgments and proclamations from a distance. Thoughtful people on both sides of the plant-based vs animal-based debate must do the hard work of analyzing the ingredients within these diets. If we truly care about the health and well-being of our fellow human beings, we owe it to ourselves and others to stay curious and open-minded. We must take the time to learn and appreciate how the foods we choose to eat operate within the human body, to understand and be honest about the real risks and benefits of the diets we personally eat and professionally recommend, and to acknowledge the limitations of our knowledge.

In my personal life, I am considered crazy—“orthorexic,” to use the clinical term—for eating a mostly-meat diet by a good many people, including some of my best friends and most highly-educated colleagues. As a result, my instinct is to rush to the defense of vegetarian and vegans who are similarly judged for their dietary choices.

In my clinical experience I have certainly worked with people with obsessive-compulsive tendencies and/or eating disorders who adopted a vegan diet because removing meat appealed to their desire to feel in control, virtuous, safe, or perfectly clean and healthy. However, with the slowly rising popularity of low-carbohydrate, Paleo, and elimination diets, I have witnessed the very same motivating factors among some who are using extreme versions of these diets to optimize their body composition, sense of safety, macronutrient ratios, or ketone readings, sometimes to the detriment of their well-being.

Vegans vs Omnivores—surprising common ground

All vegan diets are not alike, just as all carnivorous diets are not alike. To make matters more confusing, vegan and vegetarian diets are often lumped together in scientific studies, yet vegetarian diets are a different kettle of fish substitute altogether, and deserve to be considered separately from vegan diets.

It is also important to be clear about definitions. As part of every initial intake, I ask my patients the same question about food: “Do you eat a special diet of any kind?” I cannot tell you how many people have told me they eat a vegetarian diet…that includes FISH. Numerous people report they “don’t eat meat” by which they mean they don’t eat RED meat. Lots of people say they “don’t eat carbs,” meaning they don’t eat foods with added sugar. Unfortunately, all too many people these days identify as “carboholics” (their term)—eating a diet consisting almost entirely of sugar, starch, and sweetened dairy products—unable to recall the last time they ate whole foods like eggs, chicken, non-starchy vegetables, or unsweetened nuts. Many of these people don’t identify as vegetarians, but are in essence eating a primarily vegetarian diet, having either lost interest in or developed an aversion to non-dairy animal foods.

Yes, a few of my formerly vegan and vegetarian patients have told me that their mental and/or physical health improved after adding animal foods to their diets. However, some of my patients who used to be omnivores report feeling better after removing animal foods. And I have seen countless patients over the years with severe depression and other serious mental health problems despite eating meat regularly.

What’s going on here?

These anecdotes prove nothing, but they do illustrate an important point: good mental (and physical) health is not simply about whether you eat animal foods. It is also about what else you are eating. Most vegans and omnivores eat many of the same foods, some of which make the brain very unhappy.

What ELSE is in YOUR diet?

There are dozens, if not hundreds of variables within any given diet and any given individual that influence one’s health and sense of well-being. I offer these important examples for your consideration:

Refined carbohydrates

Removing refined carbohydrates, such as sugar, flours, fruit juice, and cereals, makes ANY diet healthier. This is the most likely reason why plant-based diets appear healthier than meat-based diets in some clinical studies. All of the studies I’m aware of claiming that plant-based diets are superior to omnivorous diets suffer from the same tragic flaw. Researchers conducting these studies NEVER simply ask people to remove animal foods from their diet. They always change more than just that single variable—such as lowering fat content or adding exercise—and they always instruct people in the plant-based group to eliminate refined carbohydrates and processed foods. In almost every case, these special “plant-based” diets are then compared to a junky omnivorous diet loaded with sweets, baked goods and manufactured foodstuffs.

This is not a fair fight. How do we know whether it was the removal of the meat, refined carbs, industrially-produced oils, or artificial additives that was responsible for the benefits? I’ve engaged in countless social media conversations with plant-based diet experts in which I politely ask for scientific evidence that simply removing animal foods from the diet—without making any other changes—results in health benefits. None of them have ever been able to cite a single article for me. A good example is this exchange I had with Pritikin nutritionist James Kenney, PhD FACN, in the comments section of this MedPage article.

To attempt to address the plant vs animal question in a meaningful way, we would need to compare a whole foods plant-based diet to a whole foods animal-based diet in clinical human trials. To the best of my knowledge, this has never been done. I cannot emphasize this strongly enough: there are NO studies I am aware of demonstrating that simply removing animal foods from the diet results in any health benefits whatsoever. If you know of any, please notify me—I would love to read them!

Until we have studies comparing whole foods plant-based diets to whole foods omnivorous diets, we will have to rely on human history, physiology, biochemistry, and common sense to tell us that meat is not only harmless but healthy for humans. I have looked long and hard for evidence that meat endangers human health, to no avail. Here are a few examples of what I found instead:

WHO Says Meat Causes Cancer

Does Carnitine from Red Meat Cause Heart Disease?

The History of All-Meat (or mostly-meat) Diets

What both sides can say with tremendous confidence is that refined carbohydrates are extremely unhealthy. As for mental health in particular, processed carbohydrates literally cause brain damage in at least three specific ways:

  • Hormonal instability. I explain how refined carbohydrates put the brain and body on an invisible internal roller coaster in my Psychology Today article Stabilize Your Mood with Food.
  • Inflammation and oxidation. Most psychiatric disorders are now understood to be associated with increased markers of inflammation and oxidation in the bloodstream. (A description of these is beyond the scope of this post, but I’ll write more about it in the near future).
  • Insulin resistance of the brain. Insulin resistance (aka pre-diabetes) now affects more than 50% of Americans! Emerging evidence suggests that insulin resistance can contribute to symptoms of depression, bipolar disorder and psychosis, but the study of insulin resistance and psychiatric disorders is in its infancy. However, when it comes to Alzheimer’s Disease, it’s another story. We have powerfully compelling evidence that insulin resistance is the driving force behind most cases of garden-variety Alzheimer’s Disease, and that the brain damage caused by sugary diets begins decades before any memory symptoms become obvious. To learn more, please see “Preventing Alzheimer’s Is Easier Than You Think.”

For all of these reasons, avoiding refined carbohydrates is the single most important thing any of us can do to protect our mental health, regardless of what dietary pattern we choose.

Grains, beans, nuts and seeds

Grains and legumes are seeds—precious plant embryos—cloaked in indigestible armor, and stocked with chemical weapons to protect them from the hungry creatures and harsh environmental conditions they may face while waiting to sprout. Lectins, protease inhibitors and phytic acid are just some of the surprises lurking inside all seeds that pose serious risks to human health. This is why I believe that ANY diet—whether vegan or carnivorous—that contains significant amounts of these foods is far from optimal. This may help explain why simply adding meat to a vegan diet, or simply removing the refined carbohydrates from an omnivorous diet, doesn’t always bring the health benefits one is hoping for.

Food sensitivities

When people adopt a vegan diet they don’t just remove meat, poultry and seafood from the menu—they also eliminate eggs and dairy products, which are among the top nine most common culprits in food sensitivity and allergy syndromes. Could the reason why some people feel better on a vegan diet be an unrecognized dairy, egg, or shellfish sensitivity? On the other hand, included in the top nine food culprits are also nuts and soy, so switching to a plant-based diet may unmask these sensitivities in certain individuals and make them feel worse.

People embarking on Paleo, low-carb or ketogenic diets may find themselves consuming more cured, smoked, and fermented animal foods high in biogenic amines which can trigger complicated histamine intolerance symptoms, including anxiety and insomnia. Vegan diets are generally far lower in biogenic amines, so those with histamine issues may feel better on a vegan diet. Food sensitivities can cause a whole host of symptoms that can vary from one individual to another, including psychiatric symptoms, so it’s always worth exploring at least the common culprits if you’re not feeling up to snuff.

Omega-3/omega-6 status

Omega-3 and omega-6 fatty acids are essential to brain and body function, and since our bodies cannot make them from scratch, we must eat them regularly. Most experts agree that omega-3s and omega-6 should be roughly in balance in order for our brain cells and our immune system to work properly. The vast majority of us, whether we eat a plant-based or animal-based diet, consume FAR more omega-6 than omega-3s. Some studies estimate that most Americans eat 20 to 30 times more omega-6 than omega-3s! This is because the foods that naturally contain omega-3s—fats from naturally-raised animals, for example—are hard to find in the typical modern diet. On the other hand, omega-6 is a major component of refined seed oils like canola and soybean oil, found in nearly every processed food in the grocery store.

To achieve a healthy ratio of these essential fatty acids, we must eat foods or take supplements rich in omega-3s AND dramatically reduce the amount of omega-6 we consume. It is entirely possible that vegans who take an algae-derived supplement and avoid refined seed oils may have better fatty acid profiles than omnivores who eat lean white meats and pour canola-based dressings on their salads. We’ll dive deeper into these essential fatty acids in the next article, paying special attention to how they affect brain health, but if you can’t wait to know more, please see my detailed FATS page or try one of my short omega-3 quizzes.

Dairy products

Milk is a growth formula designed to turn a little baby cow into a bigger baby cow. All milks are naturally rich in growth hormones, growth promoting agents, and proteins specific to each species. For example–the primary protein in cow’s milk, casein, cannot be properly digested by human infants because their digestive tract doesn’t contain rennet, the enzyme required to break it down. Mammals drink milk during infancy when growing rapidly, and then are naturally weaned on to other foods. I would argue that it is metabolically and hormonally risky for us to be consuming a bovine growth formula on a regular basis throughout our lifetimes. Dairy products can cause acne, digestive problems, weight gain, gynecological issues, and other kinds of distress, depending on how sensitive you are. For more details, please see my dairy page.

Digestive disorders

Some people with gastrointestinal problems—such as Crohn’s, ulcerative colitis, or IBS—feel better when they switch from a vegetarian or vegan diet to a “Paleo” diet because grains and legumes all have tremendous potential to irritate the gastrointestinal tract. Others feel better when they switch from an omnivorous diet to a vegan diet because dairy can cause digestive problems for so many people. It should be noted that nuts and many vegetables that most Paleo folks enjoy can also cause problems for sensitive individuals. For more information, please see see my IBS article.

Contrary to popular belief, animal fat, red meat, seafood and poultry are highly digestible, easily absorbed, and non-irritating to the gastrointestinal tract. If you question the truth of this statement, simply think to yourself how often you witness undigested animal foods…shall we say…exiting your body? How about undigested plant foods? I rest my case?

The Bottom Line about Vegan Diets and Mental Health

Every person’s diet is different, every person’s system is unique, and there are many factors to consider when evaluating the health of any given diet. I am convinced that including some animal protein and fat in the diet is very important, but many will disagree. Even if I could convince everyone of the importance of animal foods to human health, I’m sure some would continue to exclude them from their diets for other important personal reasons. My reading of the evidence is that removing refined carbohydrates and processed foods is what makes plant-based diets appear healthier in clinical studies, so regardless of what you choose to keep IN your diet, make sure you get the junk OUT.

When you’re ready to learn how vegan and animal-based diets compare when it comes to essential nutrients like iron, vitamin A, and omega-3s, read the next post in this series: Your Brain On Plants: Micronutrients and Mental Health. To be notified when future articles in this “Food Fights” series become available, please sign up below.

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Nutrition Conferences 2017: Meetings of the Minds

January 30, 2017

Dr. Ede speaking at nutrition conferencesI was fortunate to participate in two excellent nutrition conferences in sunny Florida last week: LowCarbUSA’s first-ever Keto Getaway in West Palm Beach and the annual Physicians for Ancestral Health retreat in Miami. It is one thing to forge relationships online and another entirely to spend time with colleagues face-to-face. I truly value these meetings as they help me to grow and challenge my thinking. This deepens my understanding of nutrition and metabolism and improves my ability to share and apply powerful dietary principles in my writing, speaking, and clinical practice. More about these two January events below, but first—a quick look ahead!

Come to LowCarbUSA San Diego in August 2017!

I am excited to share that I’ve been invited to speak at LowCarbUSA’s flagship conference in San Diego in August 2017. You save $200 if you register by Jan 31st, and everyone is welcome! Doug Reynolds and Pam Devine bring together the world’s leading thinkers in nutrition and metabolism to inspire, educate and entertain: Taubes, Westman, Eenfeldt, Phinney, Seyfried, Volek, Gerber, and many others!

This is a very popular event drawing many hundreds of people and is expected to sell out, so be sure to sign up well in advance. CME’s for clinicians are in the works, so fellow docs, come learn what you wish you’d been taught in medical school—and have fun doing it! There are even nightly low-carb dinners on a floating steamship museum…what’s not to love? I will be speaking about the powerful role of nutrition in Alzheimer’s prevention and treatment. I hope you’ll join us, as we would love to meet you in person.

Nutrition Conferences Recap:

LowCarbUSA Keto Getaway

At LowCarbUSA West Palm Beach, I was privileged to meet in person some wonderful people whose work I have long admired, including low-carbohydrate clinical and research expert Dr. Eric Westman, nutrition and cancer specialist Miriam Kalamian, and engineer-turned-metabolism guru Ivor Cummins. I also reconnected with low-carb advocate and communicator-in-chief Jimmy Moore and Denver’s Diet Doctor Jeffry Gerber. [Unfortunately, technical difficulties prevented video recording of the conference, but if you come to LowCarbUSA San Diego this summer, you can hear many of these folks speak in person.]

Luckily, Ivor Cummins brought his own videography team—imported from Sweden—who captured Ivor’s engaging talk about insulin resistance and cholesterol testing, as well as the two-hour panel discussion and Q&A on Sunday afternoon. In-view, from left to right are Jimmy Moore, Bryon Jaymes, Miriam Kalamian, and myself. Dr. Eric Westman is off-camera to the left and Dr. Zach Bush is off-camera to the right.

Another high point of the conference was meeting Stephanie Dodier, a delightful Canadian nutritionist and weight loss coach. She graciously invited me to speak with her about food and mental health for her podcast. We had an engaging and detailed conversation and I thoroughly enjoyed talking with her. If you are on my mailing list, I will send a link as soon as the interview is posted, or you can sign up on her site to be notified.

The West Palm Beach event was so successful that it will be held again next January 19-21, 2018, so stay tuned to my site and to the LowCarbUSA site for more details as they become available.

Physicians for Ancestral Health Annual Retreat

I found the Physicians for Ancestral Health (PAH) annual meeting, as always, a treasured opportunity to spend time with a diverse, growing group of physicians and associates who believe in and prescribe dietary changes in our practices. Keynote speakers this year were metabolism and aging expert Dr. Ron Rosedale and powerhouse/pioneer Dr. Mark Cucuzzella, whose inspiring work defies characterization. My friend Dr. Deborah Gordon, an excellent family practice physician in Ashland, Oregon, gave a fascinating talk about how she treats Alzheimer’s Disease using Dr. Bredesen’s protocol. My friend Amber O’Hearn, a true expert in ketogenic diets, educated us on how ketosis differs from fasting and their impacts on hormonal balance. I strongly encourage fellow physicians to join our organization and come to our 2018 retreat next January in sunny San Diego, California.

This conference is not open to the public, but complete video content will be posted on the PAH website soon, including my presentation criticizing the World Health Organization’s report claiming that red meat causes cancer [also detailed in my article WHO Says Meat Causes Cancer?].

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Pulling Out Our Sweet Tooth

January 17, 2017

Smith College students extraordinaire Anjali Kumar and Meredith Clancey produced a wonderfully creative new 7-1/2 min video Pulling Out Our Sweet Tooth to educate college students about the dangers of sugar. I was delighted that they included an interview with me about sugar and mental health as part of their project. I think the whole thing is terrific and I especially enjoy the vintage TV commercial clips about Sugar Crisp cereal. Help them spread the word by sharing this fun video with your friends and family!

To learn more about sugar and all of the ways your body and brain will thank you if you remove it from your diet, see Gary Taubes’ brand new book The Case Against Sugar.

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Review: The Ketogenic Kitchen

July 29, 2016

Ketogenic Kitchen

The Ketogenic Kitchen: A Cookbook for Cancer

The Ketogenic Kitchen is no ordinary cookbook.

Yes, it is bursting with creative recipes and beautiful photographs of delicious dishes, but these recipes are expertly crafted to help people fight CANCER.

Most other cookbooks are useless against the Big C…unless you drop them directly on top of your tumor from a great height. In fact, most conventional “healthy” cookbooks actually feed cancer cells, because they are based on high-carbohydrate ingredients like grains, beans, fruits, starchy vegetables and juices.

In sharp contrast, nestled between the covers of The Ketogenic Kitchen lies a powerful, science-based, dietary prescription for cancer written by two women who use low carbohydrate diets to support their own recovery from cancer. In addition to culinary inspiration, you will receive guidance, motivation, and hope from women who walk the walk.

Domini Kemp and Patricia Daly: Authors You Can Trust

These are no ordinary women. The Ireland-based authors are Domini Kemp, a professional chef and former food writer for The Irish Times, and Patricia Daly, a Swiss-born nutritionist who specializes in dietary counseling for cancer patients.

We’ve both had cancer twice, and when we found that conventional nutritional advice failed adequately to support our treatment via the usual means of radiation and chemotherapy, we both independently decided to look elsewhere for answers. 1)

Both women generously share their powerful personal stories with you to provide real life inspiration. In Patricia’s case, switching to a ketogenic diet tamed her aggressive eye cancer within only a few weeks, reversing vision loss and sparing her from radical eye removal surgery. Her cancer has thankfully been quiet for over five years now.

What is the Ketogenic Diet?

A ketogenic diet is a very low-carbohydrate, moderate-protein, high-fat diet that reduces blood sugar and insulin to healthy, stable, low levels. This forces the majority of your cells to burn fat (ketones) instead of sugar (glucose). Cancer cells LOVE glucose and most can’t make the switch to ketones. Without all that excess glucose around, cancer cells struggle to survive, while your healthy cells thrive.

Fortunately I haven’t personally dealt with cancer, but I follow a ketogenic diet myself. It is the only diet I have ever found that easily controls my appetite, weight and blood sugar, all while supporting a positive sense of well-being and providing excellent energy. [You can read more about my experiences with this diet in the posts listed at the end of this article.]

The Ketogenic Kitchen: What’s Inside

The vast majority of recipes are constructed entirely of whole food ingredients. That alone makes this cookbook a healthy kitchen companion, whether you have cancer or not. I would characterize most dishes in this book as “Paleo plus dairy”:  free of grains, legumes, processed foods, and refined carbohydrates. There are a few desserts in the book sweetened with yacon syrup, maca powder, or lucuma powder. Every recipe includes a diagram showing you how many fat, protein and carbohydrate grams are in each serving.

The 449-page cookbook is beautifully organized and divided into two halves.

Domini Kemp:Low-to-Moderate Carbohydrate Plan

The first half of the book, crafted by chef Domini Kemp, is intended for people who want to eat a healthy lower carbohydrate diet without having to commit to a ketogenic diet. Some recipes are ketogenic, while others are low to moderate in carbohydrate and protein. Carbohydrate content ranges from a few grams to about 40 grams per serving. Protein content ranges from a few grams to about 50 grams per serving.

Her recipes are creative and many have an international flair: lime mint chicken parcels, lamb and prune tagine, green tea poached salmon. She also dedicates an entire chapter to vegetarian main dishes, including aubergine dengaku, and tarts made with cauliflower, almond and goat cheese.

Patricia Daly: The Ketogenic Plan

The second half was designed by Patricia Daly, whose recipes are strictly ketogenic. Protein content ranges from a few grams to about 25 grams per serving, and most dishes contain fewer than 10 grams of carbohydrate per serving. Many of her recipes rely on seeds, nuts, and high-fat dairy, which is a common pattern for ketogenic cooks, since those foods are often lower in protein and higher in fat than many types of meat, seafood, or poultry.

It can be challenging to make ketogenic recipes exciting, but Patricia has risen to the challenge: prawn-filled avocado, vegetable muffins, lamb pizza, sea bass with celeriac and chorizo puree, chicken with walnut sauce. She organizes her section of the book into weekly meal plans, which busy folks will find incredibly helpful.

Valuable Extras

Patricia Daly is an expert among experts. She has been following a ketogenic diet for more than five years, professionally counsels clients with cancer, knows the science of the ketogenic diet inside and out, and has a firm grasp on nutrition research. She includes 30 pages of information about ketogenic diets written in a way that everyone can understand. What does the science say about ketosis and cancer? Which foods are allowed and forbidden? How and when should you test your ketones and blood sugar? What should you do if you’re having difficulty transitioning into ketosis? It’s all in there.

Kemp and Daly also offer down-to-earth advice about eating a low-carbohydrate diet in the real world, such as cooking for a family and modifying recipes for children.

Wish List

I think this cookbook is a must-have for people with cancer, so I only have a few minor criticisms.

The authors are based in Europe and therefore many of the measurements are metric: grams, milliliters, etc. For my U.S.-based readers, please enjoy this handy one-page conversion table in PDF form that you can download or print.

As many of you may know, I believe that “post-agricultural” foods (grains, legumes, processed foods and dairy) are best avoided for optimum health. There are only a few recipes in this book that call for beans, soy, quinoa, or rice, and some that call for dairy. Dairy foods can stimulate our hormonal systems, including insulin and growth hormone pathways. This means that dairy products could theoretically support the survival and spread of cancer cells. However, I believe that refined carbohydrates like sugar, flour, and juice are FAR more powerful in this regard.

The Ketogenic Kitchen is actually two cookbooks in one, and I love that Domini Kemp offers options for people who want a less strict approach to a healthier diet. Just keep in mind that, while her section is entitled “The Low-Carb Way”, some recipes contain as many as 50 grams of carbohydrate per serving, which I think of as “moderate” in carbohydrate. People with insulin resistance should take care not to partake of those recipes too often.

The Bottom Line: I Highly Recommend The Ketogenic Kitchen

You don’t have to have cancer to benefit from this beautiful cookbook. The first half of the book is essentially a healthy, lower-carbohydrate, whole foods cookbook. All of us should be eating this way. The second half of the book is an expert guide to the ketogenic diet, which can be used not just to treat cancer but also to treat numerous neuropsychiatric and metabolic diseases, from Alzheimer’s disease to heart disease.

If you or a loved one has been diagnosed with cancer and want to know more about the potentially healing power of the ketogenic diet, this book is the only one I know of that can give you everything you need all in one place: scientific theory (explained in a way that is easy to understand), practical advice, gorgeous recipes, hard-earned wisdom, and real life inspiration.

Full disclosure: I am a huge fan of Patricia Daly’s pioneering work. I not only enthusiastically agreed to review her new book here, but also contributed to the collection of expert opinions published in the book.

Curious to Learn More about Ketogenic Diets or Cancer?

You may also find the following resources useful:

Tripping Over The Truththe very readable story of cancer’s true origins. It is your diet, not your DNA, that largely determines your destiny!

What Causes Cancer? My summary of cancer researcher Prof Thomas Seyfried’s groundbreaking book Cancer as a Metabolic DiseaseThis science-rich book convinced me that most cancer is not caused by genetic defects. Prof Seyfried views cancer as a mitochondrial disease that can be helped by ketogenic diets.

Ketosis for Cancer: a 5-week detailed account of my attempt to follow Prof Seyfried’s dietary recommendations for cancer, including a 3-day fasting jump-start.

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References   [ + ]

WHO Says Meat Causes Cancer?

May 11, 2016

grilled meatsDoes Meat Cause Cancer?

Last October, the World Health Organization (WHO) released a two-page report entitled Carcinogenicity of Consumption of Red and Processed Meat, warning the planet that processed meat definitely causes colorectal cancer in humans, and that red meat “probably” causes colorectal cancer in humans. The report listed a total of 20 scientific references. WHO’s frightening anti-meat proclamation made headlines worldwide and had a major impact on how people think about meat and health. While plenty of pro-meat critiques of the WHO report have been published, the majority of those I read took the WHO’s findings at face value and emphasized that the statistical risk associated with eating processed and red meat is very small.

I strongly disagree. I read the report and all of the experimental studies cited in the report. I found no scientific evidence to support the WHO’s anti-meat cries, and I think it is important to set the record straight.

Let me disclose my biases from the start (something WHO committee members should also be required to do). Eight years ago I changed from a low-fat, low-cholesterol, low-carbohydrate, high-fiber/high-plant diet to a mostly-meat diet, loaded with fat and cholesterol and quite low in fiber, and it reversed every health problem I ever had (read my story on the About page). Naturally I was worried that my new meaty menu was going to kill me, so I began digging into the science for myself and lo and behold: there was no evidence that meat increases risk for heart disease, obesity, or diabetes after all. I came to believe, based on my powerful personal experience and my reading of the research, that animal foods (meat, poultry, and seafood), complete with their natural cholesterol and fats, are good for people.

But what about cancer? Is my meat-based diet, which is working so well for me right now, putting me at risk for cancer down the road?

I am a scientifically curious psychiatrist. I love getting to the bottom of things, and my life’s work centers around helping people confront reality, no matter how complicated or unwelcome it can sometimes be. If the truth is that meat makes me feel great now but is ultimately going to do me in, I want and need to know that. Whether you eat meat only occasionally, every day, or are an all-meat zero-carber, you need to know it too, so I dove into the WHO report to see what’s what.

What I discovered was that THE WHO REPORT IS NOT A SCIENTIFIC DOCUMENT. IT IS A POLITICAL DOCUMENT. Politicians can get away with making sweeping statements to the general public that stand on shaky ground. Scientists are held to a higher standard. They are supposed to show their work, and defend their positions as objectively and honestly as humanly possible. After reading the studies upon which the WHO’s anti-meat proclamations are made, I concluded that there simply is no scientific evidence that meat causes cancer in humans.

And I am not alone.

In November 2013, 23 cancer experts from eight countries gathered in Norway to examine the science related to colon cancer and red/processed meat. They concluded:

“…the interactions between meat, gut and health outcomes such as CRC [colorectal cancer] are very complex and are not clearly pointing in one direction….Epidemiological and mechanistic data on associations between red and processed meat intake and CRC are inconsistent and underlying mechanisms are unclear…Better biomarkers of meat intake and of cancer occurrence and updated food composition databases are required for future studies.” 1)Oostindjer M et al 2014. The role of red and processed meat in colorectal cancer development: a perspective. Meat Science 97: 583–596. To read the full report: [open access]

Translation: we don’t know if meat causes colorectal cancer. Now THAT is a responsible, honest, scientific conclusion.

How the WHO?

How could the WHO have come to such a different conclusion than this recent international gathering of cancer scientists? As you will see for yourself in my analysis below, the WHO made the following irresponsible decisions:

  1. The WHO cherry-picked studies that supported its anti-meat conclusions, ignoring those that showed either no connection between meat and cancer or even a protective effect of meat on colon cancer risk. These neutral and protective studies were specifically mentioned within the studies cited by the WHO (which makes one wonder whether the WHO committee members actually read the studies referenced in its own report).
  2. The WHO relied heavily on dozens of “epidemiological” studies (which by their very nature are incapable of demonstrating a cause and effect relationship between meat and cancer) to support its claim that meat causes cancer.
  3. The WHO cited a mere SIX experimental studies suggesting a possible link between meat and colorectal cancer, four of which were conducted by the same research group.
  4. THREE of the six experimental studies were conducted solely on RATS. Rats are not humans and may not be physiologically adapted to high-meat diets. All rats were injected with powerful carcinogenic chemicals prior to being fed meat. Yes, you read that correctly.
  5. Only THREE of the six experimental studies were human studies. All were conducted with a very small number of subjects and were seriously flawed in more than one important way. Examples of flaws include using unreliable or outdated biomarkers and/or failing to include proper controls.
  6. Some of the theories put forth by the WHO about how red/processed meat might cause cancer are controversial or have already been disproved. These theories were discredited within the texts of the very same studies cited to support the WHO’s anti-meat conclusions, again suggesting that the WHO committee members either didn’t read these studies or deliberately omitted information that didn’t support the WHO’s anti-meat position.
diagram of rodent studies about meat and cancer

The first experimental study cited in the WHO report began with a description of 12 rodent studies showing either no association between meat and cancer or a protective effect of meat on cancer risk. None of these studies were mentioned in the WHO report. All rodents were either pre-injected with carcinogens or bred to be highly susceptible to cancer. (Illustration by Suzi Smith)

Does it matter whether the WHO gets it right or wrong about meat and cancer? YES.

“Strong media coverage and ambiguous research results could stimulate consumers to adapt a ‘safety first’ strategy that could result in abolishment of red meat from the diet completely. However, there are reasons to keep red meat in the diet. Red meat (beef in particular) is a nutrient dense food and typically has a better ratio of N6:N3-polyunsaturated fatty acids and significantly more vitamin A, B6 and B12, zinc and iron than white meat (compared values from the Dutch Food Composition Database 2013, raw meat). Iron deficiencies are still common in parts of the populations in both developing and industrialized countries, particularly pre-school children and women of childbearing age (WHO)… Red meat also contains high levels of carnitine, coenzyme Q10, and creatine, which are bioactive compounds that may have positive effects on health.” 2)Oostindjer M et al 2014. The role of red and processed meat in colorectal cancer development: a perspective. Meat Science 97: 583–596.

The bottom line is that there is no good evidence that unprocessed red meat increases our risk for cancer. Fresh red meat is a highly nutritious food which has formed the foundation of human diets for nearly two million years. Red meat is a concentrated source of easily digestible, highly bioavailable protein, essential vitamins and minerals. These nutrients are more difficult to obtain from plant sources.

It makes no sense to blame an ancient, natural, whole food for the skyrocketing rates of cancer in modern times. I’m not interested in defending the reputation of processed meat (or processed foods of any kind, for that matter), but even the science behind processed meat and cancer is unconvincing, as I think you’ll agree.

Ready? Hold your nose, we’re going in.

The Epidemiological “Evidence” Against Meat

The WHO looked at more than 800 “epidemiological” (more about that word in a moment) human studies of red/processed meat and cancers of all kinds. Of the 16 types of cancer explored, the WHO chose to base its doomsday decree on studies of colorectal cancer only (presumably because the evidence related to other kinds of cancer was lacking).

The Epidemiology of Red Meat and Cancer

Of those 800+ epidemiological studies, a mere 29 were put forth by the WHO as “informative” about the connection between unprocessed red meat and colorectal cancer.

Of those 29 studies, 14 suggested that red meat was associated with a higher risk for colorectal cancer in humans; 15 of them did not.

The Epidemiology of Processed Meat and Cancer

As for processed meat, the WHO chose 27 of the 800+ studies to make its case for the cancer connection.

Of those 27 studies, 18 suggested that processed meat was associated with a higher risk for colorectal cancer in humans; 9 did not.

infographic of 800 epidemiological studies of meat and cancer

The WHO considered over 800 epidemiological studies regarding red and processed meat and cancer. They based their findings on 56 studies relating to colorectal cancer. Of the red meat studies, more than half found no link between red meat and cancer. Of the processed meat studies, 9 were “negative” and 18 were “positive.” Epidemiological studies are not experimental and should not be viewed as conclusive evidence. The outcomes of epidemiological studies should always be tested in experimental trials to confirm that correlations are not coincidental. (Illustration by Suzi Smith)

The Problem with Epidemiological Studies

Epidemiological studies are not experiments; they are untested hypotheses (guesses), and are therefore completely impotent when it comes to the ability to show cause-and-effect relationships between any two things, including things like meat and cancer. The scientific method demands that these guesses then be tested in clinical studies to see whether or not they are accurate.

Here’s an example: let’s say you are interested in understanding what causes alcoholism. You interview 10,000 alcoholics and 10,000 non-alcoholics by giving them questionnaires about their daily habits. You wonder if pretzels have something to do with drinking because your alcoholic grandfather often stumbles in late at night with pretzel crumbs on his shirt. So in your study you include the following question:  “How often have you eaten pretzels in the past two years?”  If you find that alcoholics reported eating significantly more pretzels than the teetotallers, the next day the following headline might appear in the Huffington Post:  “Eating pretzels increases risk of alcoholism.” The story that follows the headline might advise people to eat fewer pretzels to reduce their risk of alcoholism.


epidemiology-cause or coincidence?

Epidemiological studies implying that association is causation frequently result in misleading and conflicting headlines that leave us befuddled about what constitutes healthy eating. (Illustration by Suzi Smith)

Association is not causation. It could be that pretzels cause alcoholism, but it could also be that alcoholics spend more time in bars where there are lots of free pretzels. The only way to know for sure what’s going on is to do an experiment. Feed some non-alcoholics pretzels every day and watch what happens to them compared to a similar group who is banned from eating pretzels. [For an excellent review explaining the limitations of epidemiological studies of meat and human health, please see this article authored by the USDA’s National Program Leader for Human Nutrition, David Klurfeld PhD: Klurfeld DM 2015 Research gaps in evaluating the relationship of meat and health. Meat Science 109: 86–95.]

Regardless, even if you believe in the (non-existent) power of epidemiological studies to provide meaningful information about nutrition, more than half of the 29 epidemiological studies did NOT support the WHO’s stance on unprocessed red meat and colorectal cancer.

It is irresponsible and misleading to include this random collection of positive and negative epidemiological studies as evidence against meat.

The following quote is taken from one of the experimental studies cited by the WHO. The authors of the study begin their paper with this striking statement:

“In puzzling contrast with epidemiological studies, experimental studies do not support the hypothesis that red meat increases colorectal cancer risk. Among the 12 rodent studies reported in the literature, none demonstrated a specific promotional effect of red meat.” 3)Pierre FH et al 2004. Beef meat and blood sausage promote the formation of azoxymethane-induced mucin-depleted foci and aberrant crypt foci in rat colons. J Nutr 134: 2711–16.

[Oddly enough, none of these twelve “red meat is fine” studies, which the authors went on to list and describe within the text of the introduction to this article, were included in the WHO report].

I cannot emphasize enough how common it is to see statements like this in scientific papers about red meat. Over and over again, researchers see that epidemiology suggests a theoretical connection between some food and some health problem, so they conduct experiments to test the theory and find no connection. This is why our nutrition headlines are constantly changing. One day eggs are bad for you, the next day they’re fine. Epidemiologists are forever sending well-intentioned scientists on time-consuming, expensive wild goose chases, trying to prove that meat is dangerous, when all other sources–from anthropology to physiology to biochemistry to common sense—tell us that meat is nutritious and safe.

The Experimental Evidence against Red Meat

A grand total of SIX experimental studies were cited in the WHO report (references 13-15, and 18-20) as evidence that meat causes cancer, four of which were conducted by a single research group (Pierre FH and/or Santarelli RL). Three are rat studies, two are human studies, and one is a rat/human study [a study of rats and humans, not of hybrid rat-human creatures].

Let’s look at each of these carefully to see if there is cause for alarm. If you’d rather cut to the chase, click here to go directly to the summary.

STUDY 1: Red meat in rats

Reference 13: Pierre FH et al 2004. Beef meat and blood sausage promote the formation of azoxymethane-induced mucin-depleted foci and aberrant crypt foci in rat colons. J Nutr 134: 2711–16.

The purpose of this study was to determine whether heme, the iron-containing compound responsible for the redness of red meat, might be the cancer-causing ingredient within meat. The scientists designed an experiment comparing low-heme meats like chicken to high-heme meats like blood sausage:

  • Step 1. Inject rats with azoxymethane, a powerful carcinogen. Yes, you read that correctly.
  • Step 2. Remove most of the calcium from the rats’ chow (because calcium protects cells against heme).
  • Step 3. Feed rats a 60% freeze-dried meat diet containing skinless chicken (low-heme), lean beef (moderate-heme), or low-fat pork blood sausage (high-heme) for 100 days (approximately 10 rat-years)
  • Step 4: Look for pre-cancerous changes in rats’ colons.

Results: All rats, including the chicken-fed rats, developed potentially pre-cancerous changes in the colon. The more heme the meat contained, the stronger the effect was. None of the rats actually developed cancer.

These results would seem to suggest that skinless white-meat chicken can cause potentially pre-cancerous lesions, which is not what the researchers wanted to find. So they went back and examined the chicken chow more closely and found that the chicken chow contained more arachidonic acid and toxic levels of niacin compared to the other chows, and decided to blame these differences for the unwanted results. They never went back to test these theories, so there is no way to know whether the arachidonic acid or niacin were to blame. They did not go back and subject the beef or sausage chows to additional scrutiny, presumably because the results from experiments conducted with those chows supported their desired conclusions.

TRANSLATION: If you inject yourself with a powerful carcinogen, then eat a calcium-deficient, powdered chicken, beef, or pork diet every day for 10 years, and you are a rat, your colon may start to look funny. We don’t know whether or not you would eventually develop cancer.

STUDY 2: Red meat in rats

Reference 14: Pierre FH et al 2008. Beef meat promotion of dimethylhydrazine-induced colorectal carcinogenesis biomarkers is suppressed by dietary calcium. Br J Nutr 99: 1000–06.

This experiment simply builds upon the findings of those in the above experiment by adding calcium back into the 60% meat chow and showing that it completely protects against potentially pre-cancerous lesions. The authors concluded:

“The results support the concept that toxicity associated with the excess of a useful nutrient may be prevented by another nutrient.”

TRANSLATION: Adequate dietary calcium prevents your colon from looking funny if you find yourself in the unfortunate circumstances described in Reference 13.

The WHO offers three possible theories about how processed meat could cause cancer:

“Meat processing, such as curing and smoking, can result in formation of carcinogenic chemicals, including N-nitroso-compounds (NOC) and polycyclic aromatic hydrocarbons (PAH). Cooking improves the digestibility and palatability of meat, but can also produce known or suspected carcinogens, including heterocyclic aromatic amines (HAA) and PAH. High-temperature cooking by pan-frying, grilling, or barbecuing generally produces the highest amounts of these chemicals.” 4)

The authors of the next study begin by shooting holes in two of these theories:

Theory 1: Processing meat leads to the formation of “N-nitroso compounds”, which may cause cancer.

Problem with theory 1: This study’s authors point out that when rats are fed a bacon-based diet, which is high in N-nitroso compounds, they DO NOT develop signs of cancer.5)Parnaud G et al 2000. Endogenous N-nitroso compounds, and their precursors, present in bacon, do not initiate or promote aberrant crypt foci in the colon of rats. Nutrition and Cancer 38(1):74–80. [This “bacon doesn’t cause cancer in rats” study was not included in the WHO report].

Theory 2: When meat is cooked at high temperatures, compounds called “heterocyclic amines” (HAAs) can form, and these may promote cancer in rodents and monkeys.

Problems with theory 2: This study’s authors explain that chicken cooked at high heat also contains heterocyclic amines, but chicken is not associated with cancer risk (and the same is true for fish). Also, the doses of these compounds that cause cancer in animals are 1,000 to 100,000 times higher than doses found in human food.

Both of these highly questionable theories are nevertheless cited in the WHO report as evidence against processed meat.

As for the PAH theory, in case you were wondering, ALL charred, smoked, baked and toasted foods contain PAHs, including grilled vegetables, breads and cereals. In fact, breads and cereals contribute the highest amounts of PAHs to the average person’s diet,6)Bansal V and Kim K 2015 Environment International 84:26–38 but nobody studies the potentially cancerous effects of those, do they?

STUDY 3: Processed meat in rats

Reference 15:  Santarelli RL et al 2010. Meat processing and colon carcinogenesis: cooked, nitrite-treated, and oxidized high-heme cured meat promotes mucin-depleted foci in rats. Cancer Prev Res 3(7):852-64.

This study attempts to understand which aspects of meat processing might be responsible for causing potentially pre-cancerous changes in rat colons. Is it the cooking temperature? The curing method? The type of packaging?

The researchers compared a variety of pork processing methods:

  • light meat vs. dark meat
  • salt curing vs. nitrite curing
  • cooking at 50 deg C (122 F) vs cooking at 70 deg C (158 F)
  • air exposure vs vacuum packing

They pre-injected rats with a carcinogen (1,2-dimethylhydrazine), added the various types of processed meat to calcium-deficient, high-sugar chow, and fed it to rats for 100 days.

The type of processed meat that caused the worst pre-cancerous changes was the dark meat that had been cured with sodium nitrite, cooked at 158 F, and left unwrapped in the refrigerator for 5 days. None of the rats developed cancer.

TRANSLATION: If you inject yourself with a powerful carcinogen, then eat a calcium-deficient, high-sugar diet containing badly-packaged cooked ham every day for 10 years, and you are a rat, your colon may start to look funny. We don’t know whether or not you would eventually develop cancer.

STUDY 4: Processed meat in rats and humans

Reference 18:  Pierre FH et al 2013. Calcium and alpha-tocopherol suppress cured-meat promotion of chemically induced colon carcinogenesis in rats and reduce associated biomarkers in human volunteers. Am J Clin Nutr 98: 1255–62.

In this study, the researchers fed the afore-mentioned badly-packaged ham not just to rats, but to a handful of humans as well. This is important, because, in the words of the researchers themselves:

“One could argue that, owing to its specific physiological diet, the rat represents a poorly fitted model to test an overloaded meat diet. Excess of meat in species such as rodents could indeed give rise to some specific toxic pathways that are possibly not reproducible in other species.”7)Pierre FH et al 2007 Carcinogenesis 28 (2):321–327.

Translation:  Rats are not humans. Rats may not be evolutionarily adapted to be able to handle a high-meat diet, the way wolves, dogs, cats, and people are. A mostly-meat diet happens to be responsible for restoring my health, but I am not a rat.

rats are not people

Rats may not be evolutionarily adapted to be able to handle a high-meat diet, and therefore, are questionable subjects in which to evaluate the implications of meat on health. People, on the other hand, have been eating meat for nearly two million years.

AnyWHO…back to the study.

Seventeen healthy men ate 6.3 oz of our friend, the badly-packaged ham, every day for four days. Their urine and stool were then tested for five different “cancer biomarkers” (substances that may indirectly be linked with cancer risk):

  • ATNC (Apparent Total N-Nitroso Compounds)
  • TBARS (ThioBarbituric Acid Reactive Substances)
  • Fecal water cytotoxicity
  • DHN-MA (DiHydroxyNonane Mercapturic Acid
  • g-H2AX (gamma-Histone 2AX)

After eating the ham, two of the biomarkers (ATNC and TBARS) had increased. [When vitamin E and calcium were added to the ham diet, both of these markers remained normal.]

Two other biomarkers (fecal water cytotoxicity and DHN-MA, considered a good marker of oxidative damage) were unaffected by the ham.

The fifth biomarker (g-H2AX, a very reliable marker of DNA damage8)Kuo LJ and Yang LX 2008 Gamma-H2AX-a novel biomarker for DNA double-strand breaks. In Vivo 22(3):305-9, may have even improved slightly after eating the ham.

But two cancer biomarkers rose—that’s scary, right? Not really.

Both of those biomarkers, ATNC and TBARS, have been called into question by scientists:

Regarding ATNC:

The carcinogenicity of ATNC formed in the gut after eating heme from red or processed meat is unknown.9)Bastide NM et al 2011. Heme Iron from Meat and Risk of Colorectal Cancer: A Meta-analysis and a Review of the Mechanisms Involved. Cancer Prev Res 4(2): 177-184

Translation: even if badly packaged ham raises levels of ATNCs in the gut, we have no idea whether ATNCs cause cancer.

Regarding TBARS:

“Although this is an easy and inexpensive method, the use of TBARS test has received wide criticism over the years. The main problem is the lack of sensitivity and specificity, since TBA reacts with a variety of compounds such as sugars, amino acids, bilirubin and albumin, producing interference in colorimetric and fluorimetric MDA measurement. Therefore, TBARS test cannot be considered representative of oxidative stress.” 10)Grotto D et al 2009 Importance of the lipid peroxidation biomarkers and methodological aspects for malondialdehyde quantification Quim Nova 32(1): 169-174

Translation: the TBARS test is useless.

Interestingly, the authors refer to a study (conducted by a different group of scientists) that found vegetarian diets resulted in higher levels of g-H2AX (a very reliable marker of DNA damage, aka mutations) than diets containing cured meat or red meat.11)Joosen AMCP et al 2009 Carcinogenesis 30 (8): 1402–1407 [This “vegetarian diets may cause cancer” study was not mentioned in the WHO report.]

TRANSLATION: If you eat 6.3 ounces of badly packaged ham for four days in a row, your urine and stool will be higher in two substances that have no proven connection to cancer.

STUDY 5: Red meat in humans

Reference 19:  Le Leu RK et al 2015. Butyrylated starch intake can prevent red meat-induced O6-methyl-2-deoxyguanosine adducts in human rectal tissue: a randomised clinical trial. Br J Nutr 114: 220–30.

The authors of this study tried to show that unprocessed red meat causes mutations in human colon cells.

Twenty-three people were asked to include 10.6 oz per day of lean red meat (cooked beef or lamb) plus two cups of orange juice or low-fat milk in their diets for four weeks. These poor volunteers then underwent rectal biopsies, which showed a 21% increase in the number of mutations of a particular type known as “O6-MeG adducts” in their colon cells. [Researchers also expected to find an increase in ATNCs 12)apparent total N-nitroso compounds but this did not occur].

As scary as this may sound, you should know that there is a special enzyme located throughout the body, including in colon cells, called MGMT, whose sole purpose in life is to go around repairing O6-MeG mutations, because these mutations occur all the time as part of daily living. It is only when these mutations go unrepaired that there may be an increase in cancer risk.13)Christmann M et al 2011 O6 -Methylguanine-DNA methyltransferase (MGMT) in normal tissues and tumors: Enzyme activity, promoter methylation and immunohistochemistry. Biochimica et Biophysica Acta 1816: 179–190.

[In fact, in the next and last study we’ll explore, the authors chose a different kind of mutation to study because they specifically acknowledge that colon cancer risk has nothing to do with the number of O6-MeG mutations, but instead is related to low activity of the MGMT repair enzyme14)Lewin MH et al 2006. Red meat enhances the colonic formation of the DNA adduct O6-carboxymethyl guanine: implications for colorectal cancer risk. Cancer Res 66: 1859–65.]

However, EVEN IF these O6-MeG mutations were to go unrepaired, and EVEN IF they were to have the potential to lead to cancer, this study wasn’t designed in a way that can tell us that red meat was to blame. The authors did not report what else the volunteers were eating over the course of those four weeks other than the red meat, milk and/or orange juice. They do tell us, though, that during the high-meat phases of the study, participants ate significantly more protein (19% more) and significantly less fiber (26% less) than during the low-meat phases of the study, therefore the study wasn’t properly controlled.

In the second phase of this study, a special fiber supplement (butyrylated high-amylose maize starch) was added to the diet, and it completely blocked the increase in O6-MeG mutations. [This fiber experiment explains why subjects were asked to add milk or orange juice to their diets—they needed something to dissolve the fiber supplement in. Milk and orange juice have very different nutritional properties (most notably sugar content). If you include beverages in your experiment, you should ask everyone in the study to drink the same beverage and ideally include a control group that doesn’t add the beverage to their diet.]

TRANSLATION: If you include 10.6 ounces of lean beef or lamb plus two cups of milk or orange juice in your usual diet every day for a month, biopsies of your rectum will show a 21% increase in the usual number of mutations in your colon cells. We do not know whether it was the red meat, orange juice, milk, higher protein intake, lower fiber intake, or some other aspect of the diet that led to the increase in mutation rate. These mutations are typically automatically repaired by the body and do not increase your risk for cancer.

STUDY 6: Red meat in humans

Reference 20:  Lewin MH et al 2006. Red meat enhances the colonic formation of the DNA adduct O6-carboxymethyl guanine: implications for colorectal cancer risk. Cancer Res 66: 1859–65.

The purpose of this study was to try to demonstrate the effects of red meat and fiber on colon mutations in humans. Twenty-five people were confined to a metabolic ward and fed one of three diets:

  • a vegetarian diet
  • a low-fiber diet containing 14.8 oz of red meat per day
  • a high-fiber diet containing 14.8 oz of red meat per day

After 10 days, stool samples were tested for “cancer biomarker” ATNC 15)apparent total N-nitroso compounds and for a particular type of colon cell mutation called O6-CMG.

The low-fiber, red-meat diet resulted in higher numbers of O6-CMG mutations than the vegetarian diet, as well as higher ATNCs. Should we worry?

Regarding the ATNCs: we discussed earlier that their relationship to human cancer has not been established. As for the mutations, if you’ll recall, mutations happen all the time, and are not worrisome unless the body can’t repair them.

Regarding the O6-CMG mutations: this study was conducted in 2006, back when scientists thought that O6-CMG mutations couldn’t be repaired by the MGMT repair enzyme normally present in our bodies. However, in 2013, researchers discovered that MGMT is able to repair O6-CMG mutations after all, so we have since learned that an increase in the number of these mutations is not a cause for concern. 16)Senthong P et al Nucleic Acids Res. 2013 Mar; 41(5): 3047–3055.

Furthermore, there were numerous methodological problems with this study.

  • Even though the volunteers were being carefully fed in a supervised metabolic ward, the composition of their diets was not described in the paper. For example, we don’t know how much carbohydrate, protein, or fat they ate. Also, unfortunately, the low-fiber meat group was fed refined carbohydrates in place of high-fiber foods.
  • To make matters worse, if any volunteer started losing weight, he/she was fed buttered marmalade bread to restore weight. We are not told which volunteers received these additional sugary treats, nor how often.
  • There was no non-red meat animal protein control (i.e. chicken or fish). The age and health status of the volunteers were not provided.

TRANSLATION: If you eat a low-fiber, high-protein, high refined carbohydrate diet that includes 14.8 ounces of lean beef or lamb for 10 days, your colon cells will experience more mutations than usual. We have no idea what aspect of this diet is responsible for the increase in mutation rate. These mutations are typically automatically repaired by the body and should not increase your risk for cancer.

The Experimental Evidence: Should you Worry?

I personally think the first three studies of carcinogen-injected rats are not only ludicrous, but irrelevant to human health, and can be dismissed.

I also find the rat-human study of ham unconvincing; the biomarker results were all over the place, and I don’t care about the health effects of dried-up ham.

In my opinion, only the final two studies cited are worth considering, because a) they are human studies and b) they use unprocessed red meat. They both propose that heme, which is what makes red meat red, can increase mutations in colon cells.

Unfortunately, these two studies were not designed in a way that could prove that it was red meat that caused mutation rates to increase, but let’s just say for the sake of argument that red meat increases mutations. There still may not be any cause for alarm, because:

  • Mutations occur constantly as a normal part of everyday life.
  • Mutations are caused by a wide variety of natural stimuli– from within our bodies, from the foods we eat, and from the environment.
  • Our bodies have evolved numerous, sophisticated mechanisms to neutralize mutations.
  • Mutation rates may have nothing to do with cancer risk. [Please see my series What Causes Cancer?].

However, just because these two studies were poorly designed doesn’t mean we should discard the theory that heme might pose health risks to humans. Could heme be the cancer-causing culprit lurking within red meat?

Not according to this 2015 statement written by David Klurfeld, PhD, the USDA’s National Program Leader for Human Nutrition:

“While heme iron can increase cell proliferation in the colonic mucosa of mice and catalyze the formation of N-nitroso compounds in rats, there is no data that normal levels of heme in human intestine contributes to any harm.17)Klurfeld DM 2015 Research gaps in evaluating the relationship of meat and health. Meat Science 109: 86–95

Interestingly, Dr. Klurfeld was one of the authors of the WHO report.

Bottom Line

When you get right down to it, the only plausible evidence to suggest that red meat might be risky to human colon health is contained in two, that’s TWO, human studies, both of which were very small and  poorly designed, and therefore unable to give us useful information about the effects of red meat on cancer risk. These studies are inconclusive at best, and worthless at worst.

Human nature being what it is, believing is seeing.

People looking for reasons to avoid red meat may view these two studies as concerning.

People looking for reasons to eat red meat may view these two studies as reassuring.

It is your choice, of course! I just want you to have the facts so you can make an informed decision.

Trumpeting to the world that meat causes cancer on the basis of these two studies is ridiculously irresponsible and makes a mockery of the WHO. There is ample information to suggest that the WHO’s report is biased, incomplete, and scientifically dishonest.

To reward yourself for making it to the end of this convoluted scientific journey, I invite you to enjoy a more light-hearted take on the WHO report—a poem written in the style of the beloved Dr. Seuss.

If found this article interesting, you might also enjoy the following posts:

Does Carnitine from Red Meat Cause Heart Disease?meat heart An example of how experimental scientists twist themselves into pretzels trying to connect meat with human health problems—and fail miserably.

New Dietary Guidelines Hazardous to your Health? A critique of the USDA dietary guidelines generation process, including clear evidence of anti-meat bias.

The History of All-Meat Diets

Do High-Fat Diets Cause Depression? How the inattention to laboratory animal chow ingredients render most nutrition studies conducted in rodents completely useless.

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