HUMAN HEALTH AND THE MYTHOLOGY OF MEAT

• David L. Katz

Director, Yale University Prevention Research Center; president, American College of Lifestyle Medicine; founder, the Truth Health Coalition

We Homo sapiens are constitutionally omnivorous, and have been since before sapiens was appended to the family name. That means we have choices.

While processed meat has been robustly, if not definitively, associated with adverse health outcomes, the same is not true of, say, antelope or venison or wild salmon. The distinction is worth emphasizing: Much of the meat that most people eat in the modern context is potentially hazardous to health, associated with inflammation, dyslipidemia, atherosclerosis, and increases in chronic disease risk.

But such meats as those are nearly as far from the versions truly native to the Homo sapiens experience as is diet soda relative to water. Meat, per se, is surely not toxic to human health.

Why? Because there is nothing intrinsically toxic about any given potential food. What determines toxicity is not so much the food, as the feeder, or better yet, the interaction between the two and the environmental context. Eucalyptus leaves are considerably toxic to cats, dogs, and horses, yet clearly rather the contrary for koala bears. If fish accumulate toxins because we have adulterated our oceans, the fault lies not with the fish but our environmental abuses. Toxicity is defined by adaptation and physiology. Famously, one man’s meat is another man’s poison, and that much more so when comparing across species.

Exactly the same is true of essential nutrients or foods. The limits of biological adaptation, and any given species’ expression of them, define what is essential. Universal assertions about necessary sustenance suffer the same liabilities as such declarations about toxicity.

The ardent advocates of our Stone Age hunting, or at least the modern mythology built around it, often go so far as to contend that eating meat is essential for optimal health. One argument is that meat eating was a factor in the marked increase in the size of our brains and is now vital to feed those large brains. Another argument is that meat and its high-quality protein are essential to optimize the form and function of our own muscles.

Both contentions are, in a word, baloney. Just consider gorillas, who build their massive muscle from a diet that is 97 percent vegetarian, the small remainder coming from termites and caterpillars. Or for that matter, consider a horse, such as the magnificent, Triple Crown–winning American Pharaoh: a mountain of sleek muscle built entirely from plants. Meat is not required to build muscle. Rather, animal muscle can be built from any fuel that kind of animal is adapted to burn. We Homo sapiens are, as noted, adapted to burn both plant and animal food.

As for brains, there are predatory animals with far smaller brains (or, more important, brain size to body size ratio, which is the defining metric of species intelligence) than ours, and others with larger brains; and the same is true of plant eaters. The animals with intelligence most approximating our own are vegetarians, or nearly so.

The argument that our big brains arose in the context of eating meat and therefore we must eat meat now is no more valid than the argument that our big brains arose in the context of dodging large predators and hitting rival clan members over the head with cudgels, so we should release lions, tigers, and bears into every suburb and hit one another over the head routinely. Environmental associations do not cause-and-effect requirement make.

We are neither carnivores nor herbivores. We are constitutional omnivores. There are specific aspects of our physiology particular to meat consumption, and perhaps even the consumption of cooked meat per se. There are adaptations even since the advent of civilization that are particular to dairy consumption. Valid arguments over the place of dietary meat and dairy in human health are far more challenging and nuanced than the opposing clamors would suggest and might well come down to: What meat and which kind of dairy?

Meat is not intrinsically toxic to our natively omnivorous species. Claims that it is are at odds with the elegant logic of evolution by natural selection; the two are unavoidably in conflict. But even so, we may reasonably decide that any dietary choice that places on the menu the perpetration of cruelty upon our fellow species is toxic. We may reasonably decide that any dietary choice unsustainable by more than 7 billion Homo sapiens is now, in that context, toxic. We may reasonably conclude that accelerating the depletion of aquifers is toxic. These ancillary considerations about meat are worth chewing. I cannot improve on a recent headline in IFLScience!: “Meat Is a Complex Health Issue but a Simple Climate One.” Amen.

Meat is not essential for Homo sapiens either. There are vegans among the world’s most elite athletes. There are vegetarians among the world’s great intellectuals. But the most ardent vegetarians might constructively concede that we have no true evidence that an optimal diet of only plants (vegan) is better for human health than an optimal diet of mostly plants (Mediterranean).

Perhaps the best resolution of the matter, and one entirely concordant with the reducetarian principle, is derived neither from fantasies about the Stone Age nor the canonization of cauliflower but from the real-world experience of entire populations over generations. To date, all of the Blue Zone populations discovered, recognized for exceptional longevity and vitality, practice variations on the same basic dietary theme: wholesome foods, mostly plants, in sensible combinations.

We Homo sapiens are neither constitutionally carnivorous, like cheetahs, nor constitutionally herbivorous, like the impalas they pursue. We are constitutionally omnivorous, and that means we have choices to make. We have ample information and robust reasons to make sensible choices—based on our own health, the treatment of our fellow species, the sustainability of resources, and the fate of our planet.

There can be a place for meat in human diets, assuming the meat is wholesome, from animals fed their native diets, and spared incarceration or abuse. But aggregate evidence regarding both human health and the health of the planet indicates clearly: that place should be small.