Monday, October 27, 2014

Is Meat Unhealthy? Part II

Over time, animals adapt to the foods they regularly consume.  This is how archaeologists can, for example, determine that Triceratops was an herbivore and Tyrannosaurus was a carnivore just by looking at the structure of the skeleton.  Adaptations to diet extend beyond skeletal structure, into digestion, metabolism, the brain, musculature, and other aspects of physical function.  What is our evolutionary history with meat?

Human Evolutionary History with Meat: 200 to 2.6 Million Years Ago

Mammals evolved from ancestral "mammal-like reptiles" (therapsids, then cynodonts) approximately 220 million years ago (Richard Klein. The Human Career. 2009).  Roughly 100 million years ago, placental mammals emerged.  The earliest placental mammals are thought to have been nocturnal shrew-like beasts that subsisted primarily on insects, similar to modern shrews and moles.  Mammalian teeth continued to show features specialized for insect consumption until the rise of the primates.

65 million years ago, coinciding with the evolution of the first fruiting plants, our ancestors took to the trees and became primates.  For most of the time between then and now, our ancestors likely ate the prototypical primate diet of fruit, seeds, leaves/stems, and insects (1).  Some primates also hunt smaller animals and thus eat the flesh of mammals, birds, reptiles, amphibians, and fish in addition to insects.  However, the contribution of non-insect meat to the diet is usually small.

Our ancestors diverged from those of chimpanzees, our closest living relatives, approximately 5-7 million years ago.  This suggests that our ancestors 5-7 million years ago were likely still eating a prototypical primate diet similar to modern chimpanzees: fruit, seeds, leaves/stems, insects, and non-insect meat, in descending order of importance.

Modern chimpanzees hunt and eat other animals regularly, although these foods only provide a small percentage of total calories.  In certain areas and seasons adult chimpanzees can average as much as 65 grams of meat per day (2).  This is 2.2 oz of meat per day, or, if we assume a chimp weighs 100 lbs and a human weighs 150 lbs, the equivalent of a human eating 3.3 oz of meat per day (1/5 lb). This is in addition to their consumption of insects and eggs.  However, these figures should be viewed as a maximum rather than a representative value.

The regular consumption of animal foods by chimpanzees is confirmed by stable isotope analysis, a technique that tells us what type of food "building blocks" the animals used to construct their tissues.  This technique is based upon the principle that you are, quite literally, what you eat.  Fahy and colleagues found a stable isotope signature consistent with regular animal food consumption in chimps in a Côte d'Ivoire park, although as expected plant foods were by far the main calorie source (3).  Males ate more meat than females, and successful hunters ate more meat than unsuccessful hunters.  A separate stable isotope study suggested that one population of chimpanzees ate a significant quantity of meat, while a second population did not (4).  The picture that emerges is one of sporadic, modest meat intake, with substantial population and individual variability.  It seems likely that the diet of our ancestors shortly before they evolved bipedalism was similar to this.

Human Evolutionary History with Meat: 2.6 Million Years Ago to the Historical Period

Our genus Homo emerged 2.6 million years ago in East Africa (Richard Klein. The Human Career. 2009).  This transition is marked by the appearance of stone tools in the archaeological record.  Our ancestors didn't waste any time using these tools to eat other animals, as demonstrated by the piles of bones with tool cut marks they left behind.

We really have no idea what proportion of the early Homo diet came from meat.  It's tempting to look at piles of bones and imagine a meat-heavy diet, but since plant foods don't leave many traces, there's no way to determine from a two-million-year-old archaeological site how important meat was in the diet.  All we know is that they ate some meat.  Although humans eventually became top-level predators, we also don't know whether these early humans were actively hunting, or simply scavenging what other predators left behind-- perhaps using their tools to access gristle, brain, and marrow inaccessible to other animals.

At the same time as tool-marked bones appear in the archaeological record, early humans began undergoing a remarkable physical transformation, which represented (in large part) a progressive genetic adaptation to a new subsistence strategy.  Our brain doubled in volume, our gut became smaller, and the proportion of small intestine to large intestine increased.  Our teeth and jaws became smaller and less robust (Daniel Lieberman. The Story of the Human Body. 2013).

What does this signify?  The consensus is that these changes occurred in response to a shift toward a so-called "high-quality" diet.  This means a diet that has a higher calorie density and contains less fiber, relative to the typical primate diet of leaves and low-calorie fruit (the latter is not at all suitable for a modern human).  The small intestine is what breaks down and absorbs protein, carbohydrate, and fat, while the large intestine ferments fiber to extract calories from it.  The shift from a large-intestine-dominant gut to a small-intestine-dominant gut signifies a shift from getting most calories from intestinal fiber fermentation, to getting most calories from direct absorption of protein, carbohydrate, and fat.

What constituted this "high-quality" diet?  No one knows for sure, but it's thought to have been some combination of meat and starchy foods such as tubers, gradually displacing leaves and low-calorie fruit.  If starchy tubers were on the menu, that implies that we may have been cooking our food much longer ago than previously thought, which is possible but highly speculative.  The first clear example of fire use by humans is dated to 780,000 years ago-- long after we had begun adapting to a high-quality diet (Richard Klein. The Human Career. 2009).  That does not rule out earlier use of fire.  It's unclear to what degree our Homo ancestors relied on starchy tubers before the widespread use of fire for cooking food (tubers have a much lower food value when eaten raw).  We know for certain, however, that meat was on the menu.

A number of studies have been conducted on the diet of ancient humans and related species, using stable isotopes and other methods.  Due to the complexity of interpreting these data when little is known about the diet or ecological context, the best we can say is that our ancient ancestors ate a diverse diet (5, Richard Klein. The Human Career. 2009).  Data from more recent Paleolithic human hunter-gatherers in Europe (both Homo sapiens and Homo neanderthalensis) suggest that they probably consumed a substantial amount of meat, as part of a diverse omnivorous diet.

Human Evolutionary History with Meat: Historical Period to Present

Throughout all of recorded history including today, virtually all cultures have eaten meat.  The only exceptions I'm aware of are cultures whose religion forbids meat consumption.  Craving and seeking meat is a trait that nearly all humans share, and many go to great lengths to obtain it.  It seems we have a natural affinity for meat.  However, meat consumption varies dramatically between populations, mostly as a result of restricted availability in some parts of the world.

Current and historical hunter-gatherers offer us a window into the possible diets of our ancestors, allowing us to flesh out the rough outline that archaeology provides us.  The most comprehensive analysis of animal food consumption by hunter-gatherer cultures was published by Loren Cordain and colleagues in 2000, with University of Michigan anthropologist John Speth as senior author (6).  They sorted through data on 229 hunter-gather cultures and arrived at the following conclusions:
  1. None were vegetarian or vegan.
  2. Animal food consumption varied widely between cultures.
  3. On average, animal foods supplied more than half of all calories.
Some have criticized the conclusions of this paper, arguing that the underlying data are poor quality because they often rely on anecdotal and non-systematic accounts of diet, and sometimes include cultures that had access to guns.  This is true-- much of the underlying data are poor quality-- but this paper is the best estimate we currently have.  It is also roughly consistent with the few available detailed analyses of hunter-gatherer diets (e.g., Richard Lee's work with the !Kung).

I think we can tentatively state, based on historical data, that our more recent hunter-gatherer ancestors probably ate a substantial quantity of animal foods.  However, it's hard to say exactly how much.  As we see among contemporary hunter-gatherer societies, meat intake probably varied widely based on local availability.

Beginning about 12,000 years ago, humans around the globe independently developed agriculture.  In most locations, this eventually resulted in an extreme dietary shift away from animal foods and toward starchy grains, tubers, and legumes.  This dietary shift, when added to the infectious disease burden resulting from higher population densities and sedentism, was not good for our ancestors' health.  Early agriculturalists were typically smaller, sicker, and shorter-lived than the hunter-gatherers that preceded them (Cohen and Armelagos. Paleopathology at the Origins of Agriculture. 1984; Cohen. Health and the Rise of Civilization. 1991).  However, over time agricultural populations bounced back, presumably as their cultures and genomes adapted to the agricultural way of life.

Today, non-industrial agricultural populations tend to be of similar height and health status as hunter-gatherers, as long as they have access to a diverse diet providing sufficient calories and protein.  All non-industrial agricultural populations I'm aware of eat meat, although typically in modest quantity.


It's likely that our ancestors have been eating animal foods continuously for at least 100 million years,  and probably longer than that.  Due to this extremely deep evolutionary history with meat, we almost certainly bear genetic adaptations to animal food consumption.

Our strong affinity for meat drives humans around the world to accept substantial risk and expense to obtain it.  This suggests that meat may play an important role in our reproductive success.  However, exactly what role it plays is controversial.  It's easy to make a case that meat's value lies in its nutritional qualities, due to its high density of calories, protein, and micronutrients.  However, others have argued that hunting and meat consumption play a social role-- as a way for males to demonstrate their cleverness, bravery, and physical prowess to others.

Both explanations make sense to me, but it's clear that the nutritional explanation is part of the picture.  The reason is that humans are obligate omnivores: we have an absolute dietary requirement for vitamin B12.  Besides modern nutritional supplements, animal foods are the only food category that has been convincingly demonstrated to supply this nutrient in sufficient quantity.  This strengthens the argument that 1) our ancestors have been eating animal foods continuously for a very long time, and 2) we are genetically adapted to animal food consumption.

That said, the evidence also suggests that we're probably adapted to diets of widely varying meat content.  We aren't carnivores, and our ancestors have often gotten by on omnivorous diets containing only small amounts of meat.

Take-away points:
  • Our ancestors have been eating meat for at least 100 million years.
  • The prototypical primate diet is low in meat.
  • Humans are obligate omnivores.
  • Human cultures vary widely in meat intake, but they nearly all eat some meat.


Simon Whyatt said...

I wondered if you'd come across "Catching Fire: How Cooking made us Human" by Richard Wrangham?

He postulates that it was primarily the increased nutrient and calorie availability brought about by cooking a food preparation that lead to the shift toward smaller guts and bigger brains you mention above and makes a fairly convincing argument.

For me, this raises an interesting question - Increased calorie density, whether through the addition of meat and tubers, and/or cooking and food preparation techniques, is widely believed to be a driving factor behind our evolution.

On the flip side, increased calorie density and palatability through modern food processing techniques is blamed by many as a driving factor behind obesity and weight gain.

Is there some kind of sweet spot of food processing/calorie density?

Or is it more to do with the balance between effort and reward?

If we still had to make the effort to hunt and gather for the foods you post on food reward Friday, would we be as likely to over consume them? Or is it the combination of the perfect storm of reduced effort with increased reward/calorie density which is the issue?

Micha said...

Dear Stephan,

Thank you for this (and all other) articles. My question is what do you mean with the word 'meat' in this blog post. Is meat to mean the flesh of land-roving mammals or do you also include (shell)fish and insects, categories that are more likely gathered than hunted.

Pauly Baby said...

I can accept that humans have been historically omnivorous...clearly, eating meat is a survival tool that allowed us to migrate into temperated climes. I can also accept that meat can be instrumental in achieving a certain level of aesthetic fitness akin to using anabolic steroids. What I do not think can be demonstrated, however, is that chronic frequent meat-eating over 5% of total daily calories is necessary for or contributes to a state of health and longevity. It's a pick-your-poison meat and die in your 40's-60's of heart disease/cancer or avoid it and live healthfully into your 80's and beyond.

Tucker Goodrich said...

"All non-industrial agricultural populations I'm aware of eat meat, although typically in modest quantity."

Nice post, as usual. The only exception to the above statement I'm aware of is members of the Jain religion of India. They are not vegan, however, and depend on dairy products for the nutrients other societies get from meat (vit. B12, among others).

Ted Fair said...

Nice article, thanks for the research

raphi said...

Doesn't being an "obligate omnivore" imply that plant foods retain an 'essential' quality for the organism?

Wouldn't "omnivore" describe us more accurately?

Erik Arnesen said...

I wanted to ask you about "Catching Fire" by Richard Wrangham too, but see that Simon beat me. :) As you may know, Wrangham's hypothesis is that what gave rise to the genus Homo was the control of fire and the advent of cooked meals. Cooking made food more digestible and safer, and even transformed our ancestors' physiology.

He believes that meat eating can explain how Homo habilis came to be, but that the evolution from H. habilis to H. erectus (about 1,8-1,9 million years ago) was a result of cooking.

Joe Mason said...

Dear Pauli,
Your comment that chronic meat consumption over 5% is not consistent with health and longevity, runs counter to our evolutionary history. The 5% meat comsumption you suggest would be more in-line with our primate ancestors, which have a significantly shorter life expectancy than human hunter-gatherers, (Hill, K. 2001). Human extended life span and longer childhood development occurred millions of years after diverging from our primate ancestors. If Cordan, et al. are reasonably close in estimating that half of calories consumed by hunter-gatherers are from animal sources, and human life spans increased over that evolutionary time span as compared to other primates, then perhaps access to significant amounts of animal protein and fats had an important role to play in that increase.

Miki said...

Thanks Stephan. Two remarks: 1. I wonder what you mean by "obligated omnivore"? one that have to consume both plant and meat? 2. The Cooking Hypothesis is very weakly supported. A paper in the next edition of The Journal of Human Evolution more or less put another big nail in nail in its coffin. A multi-layer cave (Tabun in Israel) show no habitual use of fire from 800 Kya until ca 350 Kya and a sudden appearance of habitual use ever since. This papers agrees with other papers that also find a sudden appearance of fire in other sites in the Levant and Europe around 400 Kya. Lacking habitual use of fire reduces the probability of a significant consumption of tubers and consequently raise the probability of a very high consumption of meat at least until 400 Kya, and as you mention a similar picture is evident from isotope research from Europe of 50 – 10 Kya. In summary, a very high consumption of meat during most of our evolution seems more likely than any other hypothesis.

Stephan Guyenet said...

Hi Simon and Erik,

I haven't read Wrangham's book, but I am familiar with the basic premise. It makes a lot of sense. Cooking clearly offers huge advantages because it increases the quantity of digestible calories in food (especially starches but also meat) and sterilizes it.

I'm not an archaeologist and I don't claim to have special knowledge about the history of human use of fire. However, my reading, including Klein's 2009 archaeology textbook I cited, indicates that it's currently highly speculative to say that we used fire regularly prior to 780,000 years ago. Even the evidence for fire use 780,000 years ago is from an isolated site in Israel-- not widespread. The first evidence of regular and widespread fire use was in Paleolithic Europe much later than that.

It's entirely possible that we were cooking food more than a million years ago, and that would certainly be consistent with the "high-quality diet" hypothesis that explains many of our digestive features. But my understanding is that we can only speculate at this point.

Stephan Guyenet said...

Hi Miki,

Yes, I mean that we have to consume both plants and animals for good multi-generational health. We can subsist on plant-only or animal-only diets for years at a time, but when it comes to long-term health and reproduction, both diet styles fall short. I'm not aware of any human culture that has had a purely animal-based or purely plant-based diet for generations.

Thanks for your thoughts on fire. It is indeed difficult to imagine a large amount of calories coming from tuber starch without cooking. However, salivary amylase copy number is elevated in all human populations, so we must have been eating a meaningful amount of starch for at least 100,000+ years (oldest human lineages split off around then).

Miki said...

Hi Stephan
It makes sense that Homo always consumed plants, mainly because his protein consumption is limited long term to about 35% of diet and it is unlikely that it was easy for him (except in the north pole) to obtain 65% of his calories from fat on a constant basis. Regarding AMY1 it seems to me to be a very recent development. Until today the range in humans is 2 to 15 copies, even in groups that consume carbs. There is an association between obesity and diabetes and AMY1 copy numbers. So it seems that we are not yet fully adapted on that front. If we started 100 Kya we would probably all be fully adapted already. My guess (based on stable nitrogen isotope research) is 15-20 Kya beginning gradually and an acceleration after the agricultural revolution.

Ash Simmonds said...

Nice round-up, not sure how you came to the conclusion of "obligate omnivore" though.

Obligate implies a necessity - in that way your text which notes a need for animal-based nutrients but not plant-sourced can be interpreted as we are obligate carnivores, but opportunistic or supplemental omnivores.

Michael Svensson said...

Hi Stephen. Good research as usual. Looking forward to future articles on the subject.

Are you going to address the association between milk consumtion and cancer and cardiovascular disease later in this series of articles?

It has been published many articles in recent years, demonstrating a correlation between milk consumption and diseases such as cancer and cardiovascular disease, but I don't know if they are convicing enough yet?

Today an article was published in "British medical journal" that examined whether high milk consumption is associated with mortality and fractures in women and men.

"Research Milk intake and risk of mortality and fractures in women and men: cohort studies BMJ 2014"

But also other articles

Newmark HL, Heaney RP. Dairy products and prostate cancer risk. Nutr Cancer. 2010;62(3):297-9.

Qin L, Xu J, Wang P, Tong J, Hoshi K. Milk consumption is a risk factor for prostate cancer in Western countries: evidence from cohort studies. Asia Pac J Clin Nutr. 2007;16:467–476.

Song Y, Chavarro JE, Cao Y, et al. Whole milk intake is associated with prostate cancer-specific mortality among U.S. male physicians. J Nutr. 2013;143:189-196.

Chan JM, Stampfer MJ, Ma J, Gann PH, Gaziano JM, Giovannucci E. Dairy products, calcium, and prostate cancer risk in the Physicians’ Health Study. Am J Clin Nutr. 2001;74:549-554.

Kroenke CH, Kwan ML, Sweeney C, Castillo A, Caan Bette J. High-and low-fat dairy intake, recurrence, and mortality after breast cancer diagnosis. J Natl Cancer Inst. 2013;105:616-623.

Is there any healthy culture besides Masai who eat dairy products? Almost all healthy cultures eat starches and meats in different quantities, but milk consumption is extremely rare. It also raises the question if it's possible to compare conventionally produced milk with raw milk fermented milk like Masai consume?

Honey Razwell said...

Yes, unfortunately, coronary artery disease is older than the Great Pyramid of Giza.

Egyptian mummies were loaded with diseased arteries. Obesity itself is nothing new. It dates back to 23,000 BCE

People are fragile and human.

Diseases happen as my buddy Urgelt notes.

Is meat unhealthful? Time will tell. As we learn more about how cells work and how nutrients affect the, What we NEED is COLLABORATION between physicists and biologists. The different disciplines MUST talk to each other as physicist Dr. David Gross notes.The different scientific disciplines talking with each other very often is ESSENTIAL. I wish it would happen.

I suppose the question is will the individual choice to stop eating meat help our planet? And am I willing to do it?

ALL paths lead to the grave regardless of what you chose.

ProfessorEd said...

If there is a bad effect from milk much of it is probably from A1 beta casein, which is about half of the casein in Western milk.

It appears lacking from the casein in Masai milk, and this has been suggested for why they show low heart attack risks (and was the basis for key patents).

In essence on form of beta casein breaks down into an opiod in the digestive system, and passes into the blood system of many, where it appears able to have adverse effects. The immune system in attacking it may also attack pancreatic beta cells, producing Type 1 diabetes, the basis for another series of patents.

The easiest entry into this literature is the work of Prof. Woodford, whose book "Devil in the Milk: Illness, Health and the Politics of A1 and A2 Milk" (March 2009) provides details.

There is more recent research which can be found referenced on his blog at

Some of his posts discuss the following (with the references).
For instance, a recent article in European Journal of Clinical Nutrition documents differences in human fecal consistency depending on the type of casein consumed, and a highly significant difference in stomach pains.

"An important paper has recently been published in the journal Peptides reporting the presence of bovine beta-casomorphin (BCM7) in urine of both healthy and autistic children." showing the opiod does make its way into humans and can be detected. It also documents a statistically significant assoication with autistic symptoms.

"Scientific evidence has linked bovine BCM7 to many health conditions such as Type 1 diabetes and heart disease (4, 5), child development and symptoms of autism (6, 7). On the PUBMED database there are now more than 250 peer reviewed medical and scientific papers on casomorphins. However, the evidence that BCM7 might be a major villain for SIDS has, until now, been somewhat indirect."

This is an extremely important line of research. Anyone who plans to write on milk (hint to Dr. Guynet) should be aware of this research.

Those who consume milk should also look at it (especially in Australia and New Zealand where there is a brand of milk, A2, free of the A1 beta casein.

rummy said...

Cooking has many nutritional advantages,but it also causes cholesterol to become oxidised. Not a huge problem when infectious diseases stopped most people reaching advanced ages. But is its role in CVD and other diseases of aging as important as the likes of Fred Kummerov believe? And of course oxidised cholesterol cannot be avoided if you eat meat(steak tartare excepted).

LPaForLife said...

Yes there are healthy cultures. Two long lived Blue zone cultures in Sardinia and the Greek Islands use dairy products, mostly from sheep or goat.

As you are probably aware there are many studies that show positive aspects to dairy.

Another controversial aspect of dairy is the idea that Dairy has different amounts of A1 and A2 Beta Casein depending upon the animal and the breed. It is interesting that both of the blue zones above are high in the A2 form. The Swiss mountain people have cows that are also high in A2. They are purported to be very healthy. It is interesting that my ancestry is from the South Mediterranean and I sometimes can not tolerate the A1 form, but am always fine with the A2 form.

Jack C said...

Recent studies found that BMC7, "the milk devil" is broken down during fermentation of milk products such as cheese and yogurt

Hmmmm said...

I do not think you answered your own question which I understand was "Is Meat Unhealthy?". I will provide a link to someone who has.

Also, what is your evidence that we humans cannot eat all plants or all animals? There is evidence that eating all plants can be health promoting and you were introduced to people at the McDougall weekend that eat entirely plant based. You may be already familiar with the experiment where men called Stefansson and Anderson ate only meat for one year. I tried to look up a link for you to follow and found this
Plant positive also discusses this in detail.
Just because humans can eat meat, should they?

Kevin said...

The takeaway point:
'Our ancestors have been eating meat for at least 100 million years'
seems to be missing a big point. Your blog post indicates that the majority of that 100 million years was spent eating insects. Most claims that meat is unhealthy focus on red meat vs chicken. So how does a long history of eating insects relate to eating cows?

Stephan Guyenet said...

Hi Hmmm,

Stay tuned-- I'm just getting started.

Hi Kevin,

I'll address that-- stay tuned. There are plenty of people who think all animal foods are unhealthy and that we should avoid them all for health reasons (e.g., the "Plant Positive" guy referenced in the comment above yours). Both flavors of the question need to be addressed.

JMo said...


Thanks for this series of posts. I have to agree with Hmmmm above, though--I don't think you fully answered your own question, and I'll definitely stay tuned to see how your analysis develops. I see two holes in your argument:

A) You concluded that humans are "obligate" omnivores solely on the basis of the need for vitamin B12. This strong conclusion is unwarranted for a number of reasons. 1) It is still unclear whether vitamin B12 is ever present in plant foods, in the absence of animal cross-contamination. A systematic review of the availability of vitamin B12 in plant foods can be found here: URL might indicate that the source is biased, but it isn't. See for yourself.) 2) Even if it IS the case that plant foods contain no B12, the environment inhabited by the typical hunter gatherer or primitive agrarian almost certainly contained sufficient 'cross contamination' by the bacteria of other animals, deposited on plant foods, to sustain healthy B12 levels. (This is conjecture, but primitive farms and forests are anything but "sanitary" places from a bacterial perspective.) 3) We need a truly TINY amount B12 to be healthy, and we store several YEARS worth of the nutrient in our bodies. ( - Absorption and Distribution section). A little cross-contamination would go a long way. All of this serves to show, in essence, that in a "natural" environment, eating solely plant foods that contain B12 (if any exist), or eating solely plant foods, some of which have been naturally cross contaminated, would have probably been sufficient to sustain healthy B12 levels in primates and early humans.
B) None of the arguments in A) ultimately matter. It's true that eating no animal products whatsoever, and therefore (presumably) getting no dietary vitamin B12, is "unnatural" and historically unprecedented. Yes, our ancestors ate meat and/or insects, and if they didn't (and their plant food was not contaminated with B12 producing bacteria), they would not have been able to survive. But this does not mean, and it would be improper to infer, that we SHOULD continue eating meat solely on this basis. What if it were the case that a whole-foods, plant-based vegan diet, with the addition of a B12 supplement, were superior to the more "natural" and evolutionarily vetted omnivorous diet from the standpoints of longevity, chronic disease prevention, and overall health? What then? I assume that you would not maintain that the empirically inferior omnivorous diet is the ideal, despite its aesthetic consonance with our evolutionary past.

In my estimation, the scientific research has sufficiently demonstrated (as evidenced by the work of Drs. Esselstyn, Furhman, McDougall, et al) that the vegan + B12 diet IS in fact superior to an omnivorous diet. No, a vegan+B12 diet is not "natural." Yes, it is historically and evolutionarily unprecedented. So what? So is the internet, the printing press, and civilization itself. If a whole foods vegan + B12 diet is in fact the best diet we currently know of for maximizing human health and longevity (and even athletic performance, but that is a different discussion), why should we not embrace it? In other words, why should diet itself not be understood as a form of technology? I think we should remain open to the possibility that humans could have engineered a diet (vegan+B12) for themselves that is both unprecedented AND legitimately superior. What do you think of this "diet as technology" argument? This understanding of veganism has profoundly changed my view of it (and, actually, I think it is only when the nutritional sufficiency of a vegan diet is confirmed that a discussion of veganism's ethical dimensions can begin) and I think it may change your perspective as well. What do you think? In the final analysis, could all of this this nutritional anthropology be water under the bridge?

Honey Razwell said...

I just found my password. I am back again under my own name :)

I think health is something that is out of our control to a large extent. This is scary to some people. We are all mortal and fragile. Disease happen. ALL roads lead to the grave. All.

Genetic factors are an extremely huge player. A lot of it boils down to that and there is not much you can do sometimes. We now know from extensive examination of mummies from ALL over the world that atherosclerosis is VERY commonplace.It is incredibly easy to find in ancient people.

None of these people ate a "rich diet"

Scientists note that we must reconsider what we think we know about the causes of coronary artery disease. Again, as I mentioned often , scientists do not understand how cells work that well. This has huge implications an dis apparent in this case with the mummies.

All of these RCT on diet remain rather weaker evidence. There is no explanation. Stuffing people with various foodstuffs and tracking mortality over the next several years will not cut it to make us understand this disease better. No deeply explanatory mechanism.

The Iceman "Otzi" ( loaded with atherosclerosis) was found to have specific genetic mutations that increase risk of coronary artery disease.

YES, Hunter gathers were found to be pretty much loaded with this disease. Why would these people ( Egypt, Peru American Southwest, Aleutian Islands) have very significant incidence of this disease when the mean ages of death was around 36 years of age?

Although tempting to fantasize and romanticize, ( for vegan gurus and Paleo gurus alike) both obesity and coronary artery disease are nothing new at all. Scientists have found that FOUR DIFFERENT DIETS of these ancient people were NOT at all protective against atherosclerosis.

The techniques and tools were too simplistic or non-existent to identify and diagnose it, let alone treat it for try to lower the risk of getting it back in 1900. Obesity and coronary artery disease are almost as ancient as we are. That is what genuine scientific investigation found.

The Paleo and vegan gurus are living a lie and fantasy NOT based upon what genuine science has shown us. Science shows us how we are WRONG. But there is no money for them in admitting this.

Yes, science makes us uncomfortable sometimes as Dr. Krauss and Dr. Wilzcek publicly note in their lectures.It forces us to reconsider and change how we view things.

Robert Andrew Brown said...

It is arguably important to bear in mind the likely role and influence of a shoreline diet on development of the human brain, and so in setting the terms in terms of nutrient requirements of healthy existence and optimal function.

Of course other diets will supply nutrients, and the body has limited facility to convert plant based fats to long chain fats, but arguably getting the nutrients available in a shoreline diet in equivalent amounts in other diets is not easy; and that is before the advent of nutrient depleted process foods and agricultural products.

glib said...

I think at this point there is enough evidence that K2 is in the same boat as B12, something we obtain from meat/eggs (natto notwithstanding). It was one of the main points of Price's book (that we do not thrive without K2).

The aggregation of insects with meat continues to baffle me. I think there are reasons to consider them separately. They have generally much higher micro-nutrient content, they have chitin, and they have a broad micronutrient spectrum but they are the only "meat" with low phosphorus and high calcium on average. The fat is mostly saturated.

Jack C said...

@Michael Svensson

You mentioned that a 2014 study published in the British medical journal found that high milk consumption was associated with increased mortality and fractures in Swedish women and men. For every glass of milk, the adjusted hazard ration of all cause mortality was 1.15 in women (1.15 for chd, 1.07 for cancer) and 1.03 in men.

The study also found that increased intake of fermented dairy products such as cheese and yogurt resulted the opposite effect. The decrease in mortality and fractures associated with a serving of cheese or yogurt approximated the increased in mortality and fractures that associated with a serving of milk.

The authors attributed the increase in mortality and fractures to the galactose derived from lactose, and suggested that the decrease in adverse effects associated with intake of fermented cheese and yogurt was due to the degradation of lactose during fermentation.

Another adverse effect of milk may be the atherogenic effect of beta-casomorphin 7 (BMC7)
Fermentation of cheese and yogurt degrades both lactose and galactose,and also degrades beta casopmorphin-7 (PMID 8675779, PMID: 24176353). However, the reductions in galactose and BMC7 would not be expected to provide the protective effects against CHD and fractures beyond that associated with no milk consumption.

It is probable the the protective effects of increased intake of fermented dairy products is due to vitamin K2 synthesized by fermentation of dairy. Lactose fermenting bacteria are "gram positive" bacteria that require vitamin K2 for survival as it is the essential electron carrier in their respiratory chain.

There are many subtypes of vitamin K2, MK-4 through MK-10.
MK-4 from unfermented animal foods, is a "short chain" subtype. Because all vitamin K subtypes can be converted to MK-4, M-4 is considered to have specific functions.However,
nutritional doses of MK-4 do not increase serum vitamin K2 levels in humans and will not increase carboxylation of osteocalcin. In contrast, "long chain" vitamin K2 subtypes fermentation are well absorbed and are detectable at nutritional levels (45 -90 mcgm/day) and are effective for carboxylation of osteocalcin.
Intake of a nutritional dose of MK-4 will not increase the MK-4 levels in tissues, whereas "long chain MK-7 significantly increases MK-4. Thus, long chain vitamin K2 subtypes from fermentation appear to be better suppliers of MK-4 than MK-4 itself.

The "long chain" vitamin K2 subtypes MK-8 and MK-9 produced by fermentation of diary have been found in epidemiological studies to be more effective in reducing fractures and mortality from CHD and cancer than subtype MK-4 from unfermented foods such as meat, eggs and dairy.

In summary, it does seem that consumption of "regular" milk is not such a good idea because of the adverse effects of galactose and BMC7. In contrast, consumption of fermented dairy products seems advisable because of the many protective effects of the "long chain" vitamin K2 subtypes synthesized during fermentation.

John said...

Jmos, your vegan-as-a-religion bent, is well-writ, a good read, and the idea that "we" can "engineer" a superior diet--vegan, of course, strikes a false note. (BTW McDougall's a kook)
I am far from a "localvore", so there's no advocacy in this: but most of us, especially vegans, make a deal with the devil in order to eat My Vegan Way--the devil being Big Oil. This devil, as it was (some say 'were" but that was never correct grammar), allows the finicky self-righteous vegan to sit huddled in an overheated apartment in seom northern city mid-January eating starches and fruit grown "south of the border". I write this, BTW, as a vegan. B12 is found in plants?, ABSURD! Adivce: Find a religion other plant food. Live Long and Prosper \\ //

22678d00-6bc4-11e4-aecc-97801613a833 said...

Am curious where traditional vegetarian communities like Jains, or my own South Indian one, fits into all this. is there any relevant research on this? my "traditional" vegetarian south indian diet is heavy on grains and I've never known how to reconcile that with anti-grain, paleo theories.

Miki said... explanation is the different(at least)in wheat variety. India sued Monsanto for patenting its low gluten wheat variety. By the way south India has the world highest rate of heart disease and was never a very healthy region. Look up McCarisson and Madras Punjub. Link for gluten
link for McCarrison

Jack C said...

The high rate of heart disease in south India has been attributed in part to low levels of Coenzyme Q10 that result from inadequate intake of vitamin B-12 required for endogenous synthesis of CoQ10.

TruthCkr said...

That recent article on the association between milk consumption and cardiovascular disease that Michael Svensson referenced found a protective effect, not the harmful one that was implied by his comment! And it was full-fat milk, too.

Jack C said...

@ TruthCkr

Michael Svensson referred to a half dozen articles in his comment, but the 2014 article he referenced from the BMJ, "Research Milk intake and risk of mortality and fractures in women and men" found only a negative association between milk intake and chd mortality and fractures in women. Nowhere in the article does it say that milk is protective in anyway for for men or women, whereas fermented dairy was found to be protective against CHD mortality and fractures.

While data on the fat content of milk was apparently collected in the FFQs, no results were presented in the study regarding the association between dairy fat content of milk and CHD mortality and fractures.

Perhaps you found something in supplemental data that I did not find. Let me know if that is the case.

Galina L. said...

I wish(unrealistically) for the separation of the discussions about healthiness of a meat-eating from the discussions about an ethical aspect of killing animals for food. Different people have different priorities, and when some animal rights advocates mix two topics of the conversation together,and it is easy to perceive it as a calculated attempt to scary away opponents from their favorite foods.

pmgardner said...

Regarding the "Research Milk intake and risk of mortality and fractures in women and men: cohort studies BMJ 2014" study"...

Read this analysis then decide whether the study convincingly demonstrates any association (either negative or positive) between milk intake and anything else.

kkrev said...

You have to wonder a bit about the aquatic ape hypothesis. The various bivalves, urchins, and crustaceans are nutritionally fantastic.

tomR said...

@Simon @Erik @Stephan - the alternative use of fire by humans is to artificially keep the grassland in places, where naturally a woodland would form. Basically humans - the steppe/savannah animals - terraform environmnent to be their favored place.

It has been confirmed that both Native Americans as well as Australian Aboriginals did such things.

Jack C said...

@Robert Andrew Brown: On November 2, you said:

"It is arguably important to bear in mind the likely role and influence of a shoreline diet on development of the human brain, and so in setting the terms in terms of nutrient requirements of healthy existence and optimal function." You referenced an interesting article from Scientific American: "When the sea saved humanity" 2012) which stated in brief:
At some point between 195,000 and 123,000 years ago, the population size of Homo sapiens plummeted, thanks to cold, dry climate conditions that left much of our ancestors' African homeland uninhabitable.
Everyone alive today is descended from a group of people from a single region who survived this catastrophe. The southern coast of Africa would have been one of the few spots where humans could survive during this climate crisis because it harbors an abundance of shellfish and edible plants.
Excavations of a series of sites in this region have recovered items left behind by what may have been that progenitor population.
The discoveries confirm the idea that advanced cognitive abilities evolved earlier than previously thought—and may have played a key role in the survival of the species during tough times.

Another article published about the same time, "Docosahexaenoic acid, DHA: An ancient nutrient for the modern brain", fits well with the referenced article. Major points;

-A new picture is emerging which places docosahexaenoic acid (DHA) in an integral role in the evolution of human intelligence. The creation of a new database of the fossil record has been analyzed to demonstrate that a turning point in human evolution coincides with the inclusion of seafood in the diet. Multi-generational exploitation of seafood by shore-based dwellers coincided with the rapid expansion of grey matter in the cerebral cortex which characterizes the modern human brain

-The DHA molecule has unique structural properties that provide optimal conditions for a range of cell membrane functions including grey matter, which is membrane-rich tissue. The rudimentary source of DHA is marine algae found concentrated in fish and marine oils. Mammalian cells lack the enzymes required for synthesis of alpha-linolenic acid (ALA), the precursor for all omega-3 fatty acid syntheses. Endogenous synthesis of DHA from ALA in humans is much lower and more limited than previously assumed.

-Three million years of evolution had little effect on the brain capacity of Australopithecus spp. Conversely, brain capacity doubled in the million years between Homo erectus and Homo sapiens. The growth rate of the brain was exponential in the past 200,000 years, the beginning of which time period approximates the start of the severe climate conditions discussed in the article "When the sea saved humanity"

-It is argued that the brain expansion due to the exploitation of a convenient source of high-quality marine dietary nutrients is likely to have preceded both the expansion of the grey matter and the development of language and tools making.

Miki said...

I find it difficult to accept the marine dha hypothesis. 1. Vegans' children do manage to grow a reasonable size mind without a gram of dietary dha. Most other humans do the same on very little if any marine food for mothers or children. 2. N and C isotopes studies in Europe show introduction of marine food to be a later stage, maybe 50 K years ago phenomena

Hmmmm said...

I have been checking your references and have some questions and comments.
17- link does not work
18 and 19 authored by Campbell and at least 19 seems to support the conclusion that meat consumption is associated with CVD or cancer.
20 - Willet - I must spend more time with this author, he is not yet making sense to me.
21 - Denise Minger!!! Really? She does not have education in statistics. Nor do I, do you? She is an entertaining writer but I do not trust she understands the data better than Campbell and his team of scientists that worked on the China Study Project. She is just a blogger! Geesh!
21 - study from 1963. Kind of an old study, I think. Anyway, the total fat consumption was high at 84-189g/d, everyone ate animal fat 55-173g/day and the LOW cholesterol levels were as I now understand in the level that cause heart disease at around 200mg/dl. I understand that in this homogeneous group that individuals varied in their response to their high fat diet.
23 - Tecumsey 1976. Again an old study. These people were eating a diet of 40-41% fat! I looked but could not determine what the authors considered to be the numbers for the different tertiles of cholesterol and triglycerides. If you know, please help me find this information.
24- could not read online
25- Bogalusa Heart Study diet recall of 10 year olds. Must take a break from this for now.

Anyway, I understand that the higher your serum cholesterol the less additional dietary cholesterol matters to your serum cholesterol. What would be better, would be to compare a whole foods plant based diet to one of these diets or even better a low carb diet. I know about the A to Z trial, but that was not a real comparison, the diets were much to similar. I understand that individuals vary in how they respond to dietary cholesterol as shown by 22. I understand that eating low saturated fats, trans fats and no cholesterol will likely help give a person the lowest serum cholesterol possible for that individual.

I am interested in your question. I am finding it challenging to make sense of research study papers but I intend to keep at it. I realize we need to find help from others with the work of trying to understand how diet affects health. Right now I am not finding your argument to be convincing but I am still interested in hearing it.

Logato said...

Really interesting summary of our evolutionary history as it relates to meat. I, like others who have commented, am unsure about the nuances, importance of fire and relative quantity of meat as a calorie source. And I think it's easy to get caught up in this mental tail chasing minutiae. But, to me, the takeaway conclusion is this: all generationally successful cultures ate some meat (and rarely just the muscle meat, at that). Personally, I believe this is a key understanding that should guide our modern food choices. I also feel it's wise to model our diets after historically proven eating strategies (the diets of our hunter-gatherer ancestors), rather than experimenting with "promising" ideas we don't have conclusive data on. Thanks for the post, Stephan. I admire your attention to detail.

Stephan Guyenet said...

Hi Hmmm,

I think you meant to add your comment to the next post. I just checked the reference to the raw China Study data (17), and it works fine for me. Professional epidemiologists such as Walter Willett, Frank Hu, and others have stated clearly that the China Study found no association between meat intake and cardiovascular or cancer risk, which is correct.

Regarding Denise Minger, I have not yet seen anything approaching a rational refutation of her points, from Campbell or anyone else. Campbell and other vegan diet advocates have used argument from authority and taken an arrogant and dismissive attitude toward Minger's work without actually offering a scientific defense of the bizarre methods Campbell used to come to his conclusions.

I'm not a stats whiz but I do understand basic stats and have published papers using a variety of statistical methods. The way Campbell analyzed the China Study data is inconsistent with best practices, and it's not difficult for a non-statistician to understand why. This is the scenario: you have data for 1) meat intake quantity, 2) circulating apoB (LDL particle concentration), and 3) cardiovascular mortality. Your hypothesis is that meat intake is associated with cardiovascular disease. How do you test that hypothesis?

You test it by looking for a direct association between (1) meat intake and (3) cardiovascular mortality. The problem is that meat intake and cardiovascular mortality were not associated in the China Study, and Campbell never claimed they were associated in any of his papers (to my knowledge). So what did he do? He looked for an association between (1) meat and (2) apoB, which he found. Then, he looked for an association between (2) apoB and (3) cardiovascular mortality, which he also found. Then he argued that this means meat intake is associated with cardiovascular risk, even though there was no direct association between meat intake and cardiovascular risk. No epidemiologist worth his salt would buy this kind of indirect argument. Minger is absolutely right about this, Willett and Hu made the same point, and no one has refuted it.

Campbell made a number of other similar arguments that are inconsistent with best scientific practices, but consistent with a strong desire to validate a personal belief system.

Further, Campbell glossed over what may be the largest cardiovascular association in the whole study: the large positive association between wheat consumption and cardiovascular risk. Wheat is a major plant food in the US diet. I don't know whether or not that association reflects cause and effect, but don't you think the finding at least deserves to be addressed in a serious manner?

Heather said...

Stephan, I wondered if you'd seen the following in-depth response to Denise Minger by T Colin Campbell:-

It sounds pretty persuasive to a layperson like myself and I wondered if it changes your view of The China Study in any way? The following is a quote:

In summary, Denise’s critique lacks a sense of proportionality. She gives (with considerable hyperbole, at times) the analyses of the China data more weight than they deserve by ignoring the remaining evidence discussed in the other 17 chapters in the book. The China research project was a cornerstone study, yes, but it was NOT the sole determinant of my views (as I have repeated, almost ad nauseum in my lectures). In doing so, and except for a few denigrating remarks on our experimental animal research, she also ignores the remaining findings that I presented in our book. She seems not to understand what our laboratory research was showing. Using univariate correlations mostly without adjustment for confounding factors, qualification of variable authenticity, and/or biological plausibility can lead to haphazard evidence, subject to the whims of personal bias. Also, univariate correlations of this type can lead to too much emphasis on individual nutrients and foods as potential causes of events.

He also addresses the issue of wheat in the post.

I'll admit the tone does come across as patronising.

Thanks for this series of posts by the way.

Stephan Guyenet said...

Hi Heather,

Campbell appears to not have read Minger's critique carefully enough. She adjusted her correlations extensively for confounding variables, contrary to his claim that she primarily reported univariate (unadjusted) correlations. She explained her methods in detail so that anyone could follow along and critique them if necessary. I have not yet seen a serious critique of her methods.

Campbell makes no real attempt to refute the serious concerns Minger and others have raised about his methods. His response is mostly an attempt to question Minger's credibility as a young lady without a post-college degree.

His main argument is that his position is based on data from a variety of sources, not just the China Study. That's all well and good, but it's beside the point. The question at hand is whether or not the China Study supported the hypothesis that animal food consumption is associated with cardiovascular disease and cancer. Like Minger, most researchers who have seen the data do not agree with Campbell's interpretation. Campbell offered no justification for his unusual interpretation of the study data.

Also, he may base his conclusions on a number of different lines of evidence, but his book is in fact titled "The China Study". The study is obviously an important piece of evidence for him.

Heather said...

Thanks for the reply, Stephan. I appreciate the feedback as I trust your objectivity.

Jack C said...

@TomR, you said: "the alternative use of fire by humans is to artificially keep the grassland in places, where naturally a woodland would form."----"It has been confirmed that both Native Americans as well as Australian Aboriginals did such things."

The book "1491" by Charles C. Mann contends that, contrary to what many Americans learn in school, preColumbian Indians were not sparsely settled in a pristine wilderness: rather there were huge numbers of Indians who actively molded the land around them, in part by the extensive use of fire.

The following excerpts from "1491" provide insight into the use of fire by Native Americans to manage their environment to enhance their food supply.

"Constant burning of the undergrowth increased the number of herbivores, the predators that fed on them and the people who ate them both. Rather than the thick, unbroken, monumental snarl of tree imagined by Thoreau, the great eastern forest was an ecological kaleidoscope of garden plots, blackberry rambles, pine barrens and spacious groves of chestnut, hickory and oak. The first white settlers of Ohio found woodlands that resembled English parks -- they could drive their carriages right through the trees. Fifteen miles from shore in Rhode Island Giovanni da Verrazzano found trees so widely spaced that the forest "could be penetrated even by a large army." John Smith claimed to have ridden through the Virginia forest at a gallop.

Bison roamed from New York to Georgia. A creature of the prairie, Bison were imported to the East by Native Americans along a path of indigenous fire as they changed enough forest into fallows for it to survive far outside its original range.

1637, Mass., Thomas Morton: "Of their custom of burning the country:-- The salvages are accustomed to set fire of the Country in all places where they come, and to burne it twice a year, viz.: at the Spring and the fall of the leaf. The reason that moves them to do so, is because it would other wise be so overgrown -- that it would be all a coppice wood, and the people would not be able to pass through the country out of a beaten path."

1641 -1655, New Amsterdam (Albany New York:) Adrian van der Donk, a lawyer for the Dutch West India Company, spent a lot of time upstate with the Haudenosaunee whose insistence on personal liberty fascinated him. Every fall, he remembered, the Haudenosaunee set fire to "the woods, plains and meadows" to "thin out and clear the woods of all dead substances and grass, which grow better the ensuing spring"

1792, southern Alberta: Peter Fidler, surveyor, rode with several groups of Indians for many weeks in high fire season. Fidler noted " Every fall and spring & even in the winter when there is no snow, these large plains either in one place or another is constantly on fire----"

"When Lewis and Clark headed west from Saint Lewis, they were exploring not a wilderness but a vast pasture managed by and for Native Americans". (Dale Lott, ethologist".

These accounts help explain how Native Americans were able to provide sufficient food, both meat and vegetables, to keep large populations in good health.

Olinda Spider said...

"Also, he may base his conclusions on a number of different lines of evidence, but his book is in fact titled "The China Study". The study is obviously an important piece of evidence for him."

I have heard Campbell say that that is his biggest regret about that book. He chose a publisher that gave him complete control over the content, but he did have to yield on the book's title. It was the publisher that chose to call it "The China Study" over Cambell's objections.

Stephan Guyenet said...

Hi Olinda,

Fair enough. Thanks for the additional info.

Honey Razwell said...

Hi Stephan, :)

Obviously this does not apply to you.

I see all the time in the Blogosphere the cutesy phrases about "correlations". I think a lot of studies in medicine are weak, but I want to expound on this phrase.

Some of the best science educators in the world note that: correlations can mean a hell of a lot and be very important IF, IF there is an underlying physical principle which explains the correlations. For instance, Ray Davis' solar neutrino experiment was extremely highly correlated ( correlation coefficient of greater than .95) with the value of the U.S. stock market, yet no scientist even suggested there was a relationship, nor did any write any paper about it. Of course they would not. The reason is that there was no underlying physical principle which explained the correlations- which

The correct phrase I wish I would read more among the various blogs is that : "Correlations do no mean anything, in science, UNLESS, UNLESS ( and this is important) there is an underlying physical principle which explains the correlations". That is how the pros say it.

The sheer numbers of studies only measuring effects or describing things are almost meaningless without replication AND an explanation that is open to falsification and testable. Medicine runs into this problem a lot. Studies which feature two groups stuffing foodstuffs into their mouths and doctors tracking their mortality explain nothing.They don't cut it.

We need deep explanations. Description, deep explanation and predictive, deeply explanatory testable and falsifiable theories. Without that, it is not science.

Empiricism, induction, deduction- all failed. Scientific knowledge is not 'derived' from anything- it is like all human knowledge- conjecture. We use experience to choose between theories. We certainly do not know about the nuclear reactions inside of far away stars through empiricism.Nor the curvature of space time from the senses etc. From the outset it was obvious something was wrong with empiricism.

Good explanations , ones that are "hard to vary" are the driving principle of all of science and progress. Explanations cannot be over emphasized. Prediction itself is not nearly enough.

I am rooting for anybody to make progress with coronary diseases, but until Dr. Esselstyn or any doctor , uses IVUS to test for plaques and efectiveness of intervention , the result is not up to snuff. Outdated technology won;t work.

Without explanatory theories, evidence is not science, without evidence, theory is not science. Both are required. :)

Best wishes,


Theodore said...

I must say I'm aghast that you haven't read any convincing rebuttals to Denise Minger's China Study critique. You wouldn't've had to look too far to find one. If your eyes had only wandered a few inches down the page you would've seen Denise getting torn to shreds in the comment section of her own blog. Just to give you a taste, why not google "rawfoodsos Vivek Rau" and see if you can address the criticisms he/she raises. I'm sure Denise would've addressed them herself had she not been so busy trolling the McDougall forums, or fudging graphs of heart disease incidence in war time Norway !

You may also want to read Dr Campbell's deceptively beautiful rebuttal. I'm assuming you haven't read it yet, because your concern about his use of indirect correlations was addressed very nicely in the paragraph about dynamic range.

The quote from page 106 of the book is also extremely useful. It's a testament to Dr Campbell's intellectual honesty and could've saved Denise and all the other China-Study-debunking hopefuls a lot of time if they'd actually bothered to read it. Here it is again for ease of reference:

"An impressive and informative web of information was emerging from this study. But does every potential strand or association in this mammoth study fit perfectly into this web of information ? No. Although most statistically significant strands readily fit into the web, there were a few surprises. Most, but not all, have since been explained."

I watched the video of you speaking at the Advanced Study Weekend and you seemed like a knowledgeable guy, but I'm starting to wonder how closely you actually look at what you're reading. I think if you take a more in depth look at Denise's work and the numerous criticisms it invoked, you'll realise that she'd have trouble debunking the China Study Cookbook let alone Campbell's original.

Best of luck to you anyway.

Theodore said...

Regarding the B12 issue, you seem to be unaware that a large percentage of (even grass-fed) cows and sheep require some form of B12 and/or cobalt supplementation. Not to mention a whole plethora of other supplements.

I doubt anyone would question the fact that cows and sheep are natural herbivores just because they need to take B12/cobalt supplements. Either way, I think it would be especially interesting to do a study comparing B12 levels in vegans vs B12 levels in non-vegans eating animal products that have come only from unsupplemented animals. If the results could also be adjusted for the participants' use of multivitamins that would be even more interesting.

Stephan Guyenet said...

Hi Theodore,

I have read through the comments after Minger's posts, and I was not able to identify a compelling scientific rebuttal. If you know your stats and you feel that one of them was compelling and I should reconsider, please reiterate the argument and I'll have a look.

I have read Campbell's statements in detail and they do not contain a compelling scientific rebuttal of the points raised by Minger, Willett, or Hu. Just to remind you, Willett and Hu are professional epidemiologists at Harvard, and they have stated clearly in writing that the China Study found no association between meat eating and cardiovascular disease. Campbell's rebuttal contained little rational argumentation and instead relied primarily on the ad hominem implication that Minger lacks credibility because she is a young lady without a post-college degree. He made no attempt to rebut Willett or Hu's statements about the China Study.

Regarding B12 for cows, dairy cows are supplemented because we've bred them to produce ungodly amounts of milk per day while eating grain/legume-based feed concentrate. They typically get a feed concentrate that contains corn/soybeans and vitamin and mineral supps. I don't see the relevance to humans.

Grass-fed cows don't need B12. Aurochs, cows' wild ancestors, didn't get B12 supplements. Gorillas don't get B12 supplements. Natural herbivores don't need B12. Humans do need B12, and the only two sources proven to supply sufficient B12 are animal foods and supplements.

Theodore said...

Hi Stephan

Thanks for your feedback. Clearly you're unaware of the prevalence of B12/cobalt supplementation in pasture-based animal farming systems. If you have any contacts in animal agriculture I'm sure they'll be happy to confirm what I'm saying. In the meantime the following links may shed some light on the matter:

Stephan Guyenet said...

Hi Theodore,

Your claim is that ruminants require B12 supplementation. Your references do not support that. Your references show that ruminants in areas with low soil cobalt availability benefit from cobalt supplementation. Not exactly a shocking conclusion. Certain soils are naturally low in specific minerals, including cobalt, iodine, zinc, selenium, and others, as your references detail. Correcting those deficiencies is important for healthy animals.

Cobalt is an element that is required for B12 synthesis by microorganisms, but it is not vitamin B12. If the pasture is too low in cobalt, rumen microorganisms do not have enough cobalt to produce B12. But this is only a problem in specific locations with low cobalt availability, as detailed in the references you provided.

Humans cannot supplement cobalt instead of B12, because we don't have a rumen full of B12-synthesizing bacteria. We absorb B12 in the small intestine, before significant microbial fermentation of food residue has occurred. That is why we require animal foods for B12, although in the 21st century we can also use supplements.

Theodore said...


I think you're twisting my words somewhat. I never said that ALL grass-fed ruminants require B12/cobalt supplements. In fact I was quite careful not to. But for what its worth I did speak to several pasture-based farmers back in 2010 and there wasn't one of them who didn't give their animals cobalt or B12 supplements in one form or another. Not to mention a whole host of other mineral supplements. This completely puts paid to the idea that animal products are a rock solid NATURAL source of vitamin B12. Numerous soils all over the world fail to supply ruminant animals with adequate cobalt for internal B12 synthesis. So without cobalt supplementation, animal flesh as a source of vitamin B12 would be hit and miss at best. Perhaps you can explain to me how eating animals that have been given supplements is any different from taking supplements directly.

I'll say again that it would be interesting to see a study comparing B12 levels in vegans vs B12 levels in non-vegans eating unsupplemented animals (and no multivitamins or fortified foods). I think it would also be interesting to see some studies examining the B12 status of vegans in areas where the soil is rich in cobalt. I'm not aware of any existing studies that took either of these issues into account. If you know of any then please forward me the link(s). Its certainly true that monogastric animals don't seem to use cobalt in quite the same way as ruminants, but I doubt that cobalt deficiency in the soil is completely unrelated to B12 deficiency in non-ruminant animals. I recall at least one study showing that cobalt supplementation significantly reduced hyperhomocysteinemia in pigs.

Either way, the wild setting in which our ancient ancestors lived could easily have provided enough pre-formed vitamin B12 to survive, so I'm not sure how vital internal B12 synthesis would've been to them.

I haven't forgotten your point about Drs Willet and Hu, by the way. I hope to come back to that once we've dealt with the B12 issue.


Stephan Guyenet said...

Hi Theodore,

Let's take a step back here. Please state your claim clearly so we can discuss it clearly.

My understanding is that you're arguing that animal foods are not a reliable source of B12. Is that correct?

I also understand that you are claiming that ruminants on pasture typically receive B12 supplementation. Please provide evidence of this claim or I will consider it to be incorrect based on the references you provided previously, as well as common sense.

Animals that are alive and healthy are a good source of B12, because it's a vitamin that is essential to life and health. Wild animals don't get B12 supplements, yet they supply dietary B12. It is well established that rumen bacteria synthesize B12 that ruminants then absorb for their dietary needs. There is a vast literature demonstrating quite convincingly that animal foods are a reliable source of B12 for humans, and there is no evidence of any other significant dietary source. This is just nutrition 101, textbook stuff.

You asked if vegans have lower B12 levels than omnivores. This has been studied extensively, and B12 deficiency is far more common among vegans (and vegetarians to a lesser extent) than omnivores, even though vegans are more likely to supplement B12. That's because omnivores regularly eat B12-rich animal foods.

Stephan Guyenet said...

Epic-oxford study:

"In all, 52% of vegans, 7% of vegetarians and one omnivore were classified as vitamin B12 deficient (defined as serum vitamin B12 <118 pmol/l)"

Theodore said...


No, your two most recent posts didn't even remotely speak to what I was asking. I'm not sure how much more explicit I can be, but I'll give it one last shot:

1) A large percentage of pasture-based animal farmers fortify their animals' diet with cobalt in order to prevent B12 deficiency. I spoke to several such farmers back in 2010 at various farmers markets and every single one of them was fortifying their animals' diet with some form of cobalt (as well as various other minerals).

2) Without this cobalt fortification, animal flesh as a source of B12 would be hit and miss. You say:

"Wild animals don't get B12 supplements, yet they supply dietary B12."

In fact the whole point is that they wouldn't supply much dietary B12 unless their own diet contained adequate levels of cobalt. The fact that they're alive doesn't automatically mean that they're a good source of B12. Animals don't die straight away as soon as they start running low on B12.

3) The cobalt fortification of these animals' diets represents a massive indirect B12 supplement for the people who eat the flesh and milk of those animals. Please explain to me how eating animals whose diet has been fortified with cobalt (as well as a whole host of other minerals) is any different than consuming supplements or fortified foods directly.

4) As far as I know, none of the studies comparing B12 status in vegans vs non-vegans adjusted for the indirect supplement the non-vegans were getting via the cobalt-fortified diet of the animals they were eating. If you know of any studies that did adjust for that then please post the link(s).

5) As far as I know, none of the studies comparing B12 status in vegans vs non-vegans adjusted for multivitamin use (or consumption of fortified foods) in the non-vegan subjects. If you know of any studies that did adjust for those things then please post the link(s).

6) As far as I know, none of the studies comparing B12 status in vegans vs non-vegans took into account the cobalt status of the soil in which the vegans' food was grown. Again if you know of any studies that did adjust for that then please post the link(s).

You can obviously respond to these points in any way you choose, or even ignore them completely. But I hope at the very least you'll respond to the points I've actually made rather than the points you would've liked me to have made.


Stephan Guyenet said...

Hi Theodore,

Your claim is that wild animals are a "hit and miss" source of B12. This flies in the face of common sense, and a quick perusal of conclusively refutes it:

100g wild deer meat supplies 31-60% RDA of vitamin B12 depending on the sample. Of the 6 venison samples listed on NutritionData, all 6 contained high levels of B12.

All samples of wild elk were similarly rich in B12.

Wild rabbit is rich in B12.

I'm sorry but you are simply incorrect. Wild animal foods, including ruminants not supplemented with B12 or cobalt, are consistently an excellent source of B12. Animal foods are the only known reliable dietary source of B12.

Omnivores are less likely than vegans to supplement B12 yet their B12 status is better. It's because of the animal foods. Again this is just nutrition 101.

I am going to end this "debate" now because it has become unproductive.

Honey Razwell said...

Great points about B12, Stephan. We can know what is wrong and the typical vegan B12 arguments have no evidence behind them- they are pure belief. It is difficult to argue with extreme believer types.Nothing will convince them.Campbell and his followers are unreasonable. real scientists are always willing to change their mind. That is the whole point of it all.

As Bruce Lee and other philosophers noted " They need to empty their cups , so they can taste Stephan's tea." LOL ! :)

There is no surer sign of unscientific thought than a "take-no-prisoners" view that we have a complete understanding of any given phenomenon and that it is 100 % correct.

There is NOT a SINGLE thing we can say OR conclude about the universe that is "absolutely" right or wrong. Nothing.

Recently , the it has been suggested through some early evidence that the speed of light may not be constant- rather, it might - MIGHT be variable .

The "war" will never be won against guys like Campbell because his mind is made up fully.He is unwilling to even consider anything positive in favor of meat whatsoever.

I acknowledge much remains to be discovered in nutrition- as well as physics. Roger Penrose himself said that there is much left in physics undiscovered.

Are meat extremely heavy meat diets ideal? Likely not. But only crackpots say, "Here is a chunk of meat, the cause of coronary heart disease 100 % certain." There is no deep explanation as to HOW this can be.

Campbell also misrepresents Chinese diets as a la-la land of nothing but green vegetables and no fat source. I know what they generally eat. My sister-in-law is Chinese and I have many Chinese friends - some born here.Their diets are nicely balanced and include animal and seafood.

Campbell discredits himself simply by his attitude about meat. It is unscientific as it gets from the get go. His own research is not even supporting it, let alone his undesirable certitude. He dismisses everything. Most of these vegan doctors are crackpots who have deep beliefs. They want the prestige associated with science, but are not themselves acting like genuine scientists.

I am neither for nor against meat. I know, though, that blaming it for THE 100 % cause of all of our troubles is as bad as it gets science wise.

e MUST have a deep hard to vary explanation as David Deutsch notes. Without this, no scientific progress is made.

They are not "curious characters" as Richard Phillips Feynman was.

Deutsch, Hawking, Feynman, Penrose- I wish we had those types of thinkers in the nutrition and medicine.

That we need to make much more progress with how cells work is the thorn in the side of T. Colin Campbell ( and everyone) . If I were Minger, i would mention that. That would stop Campbell in his tracks.

Take care, Stephan.


Richard Nikoley said...

Cool post, even cooler comment thread.

Stephan, have you looked at all into the relatively recent research on c4 grasses showing up on teeth (nutcracker man) and that it turns out to be the tubers (tiger nuts)?

They grow like weeds, are easy to harvest (baboons eat lots) and most interesting of all, they have a similar macro ratio to mammal milk and in terms of nutrition, edge out muscle meat.

Jen said...

Hello Stephan,

I'm wondering if you could address the claim that lacto-fermented vegetables such as krauts, kimchis, fermented brine pickles, etc. can provide vegans with adequate sources of B12? I'm not vegan, but I'm curious about the accuracy of such statements, which I see a lot (in addition to things like large amounts of B12 listed on the nutrition labels of kombucha, etc.)