Do Some People Need Meat?

Vegetarianism and Genetics

In her book Animals in Translation, Temple Grandin says that some people are genetically required to eat meat. She’s hardly alone; probably most Americans think the same thing, not to mention the Dalai Lama, who eats meat despite the first precept of Buddhism, not to take the life of any sentient creature. He believes, evidently sincerely, that he will suffer physically unless he eats meat.  Obviously, millions of vegetarians who are in excellent health demonstrate that it is equally true that some people do not need to eat meat. But the meat-eaters beg off, in an apologetic sort of way, by suggesting that not everyone is alike in this way, and Temple Grandin is a distinguished example.

Context of her remarks

In fairness to Temple Grandin, whom I greatly respect and who has done much valuable work with respect to animals, her comments occur in a larger context of talking about autism (a condition which she has). This is what she says:

"If I had my druthers humans would have evolved to be plant eaters, so we wouldn’t have to kill other animals for food. But we didn’t, and I don’t see the human race converting to vegetarianism anytime soon. I’ve tried to eat vegetarian myself, and I haven’t been able to manage it physically. I get the same feeling you get with hypoglycemia; I get dizzy and light headed, and I can’t think straight. My mother is exactly the same way, and a lot of people with processing problems have told me they have this reaction, too. . . ." (Animals in Translation, p. 179)

"A gene that contributed to autism might contribute to a metabolic difference, or any other kind of difference. Parents have always said that their autistic children have lots of physical problems, too, usually involving the gut, and mainstream researchers haven’t paid a lot of attention to this. So until someone proves otherwise I’m operating from the hypothesis that at least some people are genetically built so that they have to have meat to function." (Animals in Translation, p. 180)

There are several distinct thoughts here:

1. That humans have evolved to eat meat.

2. That autistic persons might need meat.

3. That symptoms of dizziness and light-headedness are related to a vegetarian diet in some persons.

4. That some people are genetically built to require meat.

Our Biological Evolution

The idea that humans "evolved" to eat meat is highly problematic and depends on semantics. It hinges first of all in how far back you want to take hominids, and whether you view meat-eating as an opportunistic strategy or a change in our biological nature. I don’t want to get into an involved discussion of evolutionary biology, but prima facie it is fairly obvious that this was an opportunistic strategy and did not involve any genetic evolution. Go back 5 million years, and the creatures we evolved from (and with which are extremely similar genetically) were pretty strict vegetarians. Even after we became "hominids," our exact diet was not at all clear and when, how, and to what extent meat entered the human diet is debated at great length.

But let’s move on to autism. Actually, the question of autism and diet has been studied. There is some good evidence (discussed in The McDougall Newsletter, November 2006) that autism is connected in some way with intake of gluten and dairy products. This relates not to a food deficiency, but to food toxicity. Some food ingredients (namely, allergens) are toxic to some people, but not others. Those who convert to vegetarianism often increase their intake of both wheat and milk, since they often increase their intake of all non-meat foods to "compensate" for the missing meat.

Thus, there is some evidence that autistic people really do have a negative reaction to vegetarian diets. This, however, is not due to something that meat has, that vegetables don’t (a deficiency problem), nor with vegetarianism per se, but with toxic elements found in conventional vegetarian (and nonvegetarian) diets.  

While this isn't scientific, I did find several references on the web to autistic vegans: one to autistic adults on vegan gluten-free diets, another on a neurodiversity petition (Thomas Sandifer, signatory #819), and another reference to an autistic vegan who is really upset with Temple Grandin, so I suspect an impartial study would probably conclude that autism as such does not preclude veganism.

The Evidence

And what is the evidence, for Temple Grandin, that there is a deficiency problem solved by eating meat? It is her own personal experience: light-headedness and dizziness. At this point, though, I do have to object to the comments on dizziness, light-headedness, etc., as a consequence of vegetarianism, based on my personal experience.

I’m sure that some people experience this on converting to vegetarianism -- because I myself experienced exactly these symptoms, and in a most alarming way, too. I became a vegetarian in 1978, and in 1980, at the urging of some vegan friends, decided to try veganism -- I would give up dairy and eggs in addition to meat, fish, and fowl which I had already given up. The results, over the next few months, were catastrophic. Not only did I feel light-headed and dizzy, I was tired all the time, though I found I could compensate by increasing my caffeine intake. On top of that, I started to lose weight. I was already thin, at 117 pounds or so, but promptly went down to 102 pounds. I was almost certainly protein-deficient, too, though I never went to a practitioner to try to verify this.

Alarmed at all of this, I was about to call my experiment with veganism off, but one of my vegan friends (Robin Hur) suggested an extremely simple modification of my diet -- that I start eating more food. It worked! I was accustomed to a high fat diet, even as a lacto-ovo-vegetarian, so the portion sizes I was used to just wouldn’t give me the calories I needed on a low-fat, high-fiber vegan diet. As soon as I started consciously eating larger portions, I quickly regained my weight, felt much better, and eventually weaned myself from the coffee habit as well. It may seem incredible that an intelligent, college-educated person with plenty of money for food could get in trouble by failing to eat -- wouldn’t you get hungry? -- but I can testify that it is more than theoretically possible.

So I object to anyone who complains of light-headedness and dizziness when they try vegetarianism as if that were necessarily an objection to vegetarianism. 

Social Conditioning

What we eat, and how much we eat, is often intensely socially conditioned, as Brian Wansink recently pointed out in Mindless Eating. Wansink postulates that our subjective feeling of satiety is notoriously unreliable, as we have essentially three levels of awareness:

1. Starving, want to eat now;

2. Satisfied, but could eat more;

3. Stuffed and can’t eat more, as on Thanksgiving after the third helping of pumpkin pie.

Most of our time is spent in the second category, which however encompasses a wide range of actual consumption, thus making us susceptible to other factors than subjective satiety in how much we eat.  That's why, Wansink argues, so many people overeat.  Wansink does several interesting experiments to show that this happens -- people often completely misreport how much food they’ve eaten, basing it instead on social cues or other contextual factors. Wansink is more concerned with people who overeat without realizing it, but this mechanism could operate in the case of people who undereat as well.

Which brings me to her fourth point, the working hypothesis that some people have a need for certain ingredients only found in meat. I wish to suggest a different working hypothesis, exactly the opposite: that no human being has any need for any nutrient that cannot be supplied from a non-animal source. As Karl Popper famously pointed out, it is the hallmark of a true scientific hypothesis, not that it be absolutely provable -- nothing in science can be absolutely proved, and science is constantly being modified -- but that it be refutable. If a hypothesis is refutable, but not actually refuted, then it is a strong hypothesis.

My hypothesis could be easily refuted. All you would have to do is produce a single case of a single person needing a single nutrient. Yet everything we know about nutrition, so far, and quite a bit of research has been done on this, has failed to produce such a counter-example. The most problematic nutrient is vitamin B-12, the problem which proves the rule. Vegans (but not lacto-ovo-vegetarians!) need to get a vitamin B-12 supplement, though the symptoms can take decades to develop. People such as Temple Grandin, the Dalai Lama, and countless others frequently assert that they need meat, but no one has actually identified a nutrient that anyone needs that can only be found in meat. Specific diets are often deficient (or toxic, in the case of allergens), and people may eat badly simply out of ignorance, but not because of an intrinsic problem with lack of animal foods as such.

The opposite hypothesis, that some people need meat, is a vague hypothesis that is virtually impossible to refute. To refute it, you would have to examine over 6 billion people, and verify the entire nutrient requirements of each individual human being.  (Using sampling techniques, you could show that it was improbable short of 6 billion examinations, but it would still be a lot of work and you'd never have the absolute simplicity of a single concrete counter-example as a refutation.)  In the meantime, millions of people are eating meat which has a known and serious toxicity -- because meat has cholesterol, saturated fat, etc., over long enough time it will usually kill you. This happens all the time; heart disease and cancer are the two leading causes of death in the United States.

I can’t object to someone who says that it is possible that there is some factor in meat, as yet unknown, which is not found in other foods and which autistics (or others) require. I would not necessarily object to someone who eats meat as as a matter of convenience -- some people are allergic to wheat, soy, and dairy products, and in our society it’s hard to find vegan food or recipes that don’t have wheat or soy. I would not even necessarily object to someone who eats meat as a precaution -- in a society in which there are so few vegans or vegetarians, how much work has been done on the nutritional problems of autistic vegans, an intersection of two very rare sets of people?

With those preliminaries, though, I would state that the hypothesis that some people have a genetic requirement for meat is, at its basis, unscientific. There’s been a lot of work done on nutrition for well over a hundred years; countless nutrients have been identified; countless foods have been analyzed; and there is every ideological predisposition for meat-eating scientists, in a meat-eating society, to identify nutrients that meat has that other foods don’t.

Yet despite all this, no necessary nutrient found only in meat has been identified. All the evidence that we have so far indicates that there is no nutrient which any human requires which can only be found in meat. Temple Grandin and the Dalai Lama are in abundant company. Many (perhaps most) people have a vague belief that meat is somehow necessary, at least for them -- that’s why the frenetic slaughter of 300 animals a second is going on worldwide. However, it is not very likely that this is the case.

Keith Akers
August 28, 2007