As I write this, I am about to leave for Boston to speak at iV, the Ivy League Vegan Conference, at Harvard. Prominent voices will gather there and collectively, one anticipates, make the case for veganism.
The timing is a bit ironic. A paper was just published in the Lancet, describing the lifestyle and health status of the Tsimane. The paper generated considerable excitement, and widespread media attention, because the Tsimane, a population in the Bolivian Amazon described as living “a subsistence lifestyle of hunting, gathering, fishing, and farming,” were found to have “the lowest reported levels of coronary artery disease of any population recorded to date.”
The Tsimane, obviously, are not vegans, as the references to both hunting and fishing indicate. On the other hand, they are not hunting for meat in the supermarket, as I pointed out to one correspondent who sent me the study and asked if his penchant for meat was now exonerated. My answer was perhaps, provided it was satisfied by advent of bow and arrow and involved no cellophane.
The Tsimane, in common with our Stone Age ancestors, eat the meat of wild animals and fish they obtain the hard and old-fashioned way. Those animals, in turn, get their food the hard and old-fashioned way, too; they are not fed copiously in captivity. Consequently, their own bodies are lean, and represent the fats they derive from their food sources. The result is that the Tsimane diet has virtually no trans fat, is very low in saturated fat, and is quite low in total fat. The study authors report a diet that is 72% carbohydrate, 14% fat, and 14% protein.
Of course, this diet made up of foods direct from nature is very low in simple starches, and sugars as well. The authors note that the carbohydrate sources in the Tsimane diet are generally complex, and high in fiber- just as vegetables, fruits, whole grains, beans, lentils, nuts, and seeds are. These, of course, are the plant foods all but universally recommended for health promotion.
While the inclusion of meat in the Tsimane diet, conjoined to stunningly low levels of atherosclerosis demonstrated by CT imaging of the coronary arteries, might seem a rebuke to vegan diet advocacy, it is a mild rebuke at most. The nutrient composition of the Tsimane diet is much more akin to high-quality vegan and vegetarian diets than to anything remotely like the meat-heavy diets that prevail in the U.S. and many industrialized countries.
But even a mild rebuke, born of evidence, may deserve respect and certainly warrants reflection.
I have long noted, with all due respect to the ardent vegans among my colleagues, that we lack evidence to prove that any one specific diet is the singular “best” for human health. This should come as no surprise when you consider what kinds of studies would be needed to generate such evidence: randomized trials of optimized versions of competing diets in large populations over a span of decades with incident disease and mortality the outcome measures. The diet producing the greatest combination of longevity and vitality would be the winner. Such a study has not been done, and don’t hold your breath.
What we do know, from a veritable sea of confluent evidence, is the basic theme of the optimal diet for Homo sapiens. Famously described by Michael Pollan as “food, not too much, mostly plants,” it is just so: a diet of minimally processed, wholesome foods, mostly plants, in any balanced and sensible combination. The Tsimane diet represents such a combination. So do the Blue Zone diets, encompassing traditional Mediterranean, Asian, vegetarian, and omnivorous variants.
Our species is constitutionally omnivorous. That makes it unlikely the kind of meat to which we are natively adapted, the kind of meat the Tsimane consume, would be “bad” for us as some contend. It does nothing, however, to exonerate the fatty meats of domestic animals and the processed meats that many eat under a “Paleo diet” halo.
In fact, all it really means is that our species, by virtue of our anatomy and physiology, is endowed with a particularly wide array of dietary choices.
I can’t support the argument I sometimes hear from colleagues that a vegan diet is “best” based on human health considerations alone. In fact, we know that a strictly vegan diet is sure to be deficient in at least one nutrient essential to our species, vitamin B12. Supplementing B12 is easily done, however, and a well-balanced vegan diet is certainly among the contenders for best diet laurels.
There are, however, considerations other than our own health. The meat that feeds modern appetites is overwhelmingly the meat of animals raised not just in captivity, but relatively confined spaces. Often, it is the meat of animals not fed the diet native to, or optimal for, their own species. Animal husbandry may at times involve use of hormones and antibiotics, as we have all heard. And, there can be cruelty in the mix that most of us would find distasteful, if not disgusting, if ever we saw it. There are, therefore, arguments for veganism related to ethics, the decent treatment of our fellow species, and the avoidance of exposure to harmful food contaminants.
There are compelling environmental arguments as well for veganism and approximations of it. The domestic production of meat, and beef in particular, is associated with high environmental impact in every area of importance: water consumption, land allocation, greenhouse gas emissions, and biodiversity.
I can imagine an anti-elitist rebuttal, protesting the high cost of produce- but that argument is specious. For one thing, the relative costs of foods reflect our cultural priorities, not natural law. If beef is inexpensive relative to kale, it’s because we direct subsidies to make it so, subsidies we could redirect whenever the will is mustered. For another, many of the best foods – beans, lentils, whole grains- are already exceptionally economical. And, if so inclined, we could enable the economically disadvantaged to afford better food in ways that would likely reduce health care costs into the bargain, as some are already doing.
This, then, is the message I am taking to the iV conference, as I add my voice to a chorus singing the praises of well practiced veganism. We are omnivores, and we have choices. A good vegan diet is not the only option for health promotion, but it is among the best. When the case is broadened from the health of people to that of the planet, too, the case for veganism is very much fortified. After all, the Tsimane are few; we are many.
Director, Yale University Prevention Research Center; Griffin Hospital
Immediate Past-President, American College of Lifestyle Medicine
Senior Medical Advisor, Verywell.com
Founder, The True Health Initiative