I am quite confident about the fundamental truths of diet for good health. I am quite confident because they are predicated on a massive aggregation of evidence of every description, spanning methods, populations, and decades. I am quite confident because I share these convictions with a veritable who’s who of leading experts, with predilections from vegan to Paleo, from all around the globe.
But I am not absolutely, incontrovertibly certain about much. In the company of the wisest, most thoughtful, most expert and knowledgeable people I know- I have many legitimate doubts about many details of nutrition.
I am perfectly comfortable with these uncertainties. I have long subscribed to the view best expressed by Bertrand Russell: The whole problem with the world is that fools and fanatics are always so certain of themselves, and wiser people so full of doubts.
Let’s allow for the wisdom of doubt, then, and consider the PURE study currently roiling if not the nutrition world, at least its representation to the public. These articles, which I have reviewed at length, effectively part dietary perspective like Moses and the Red Sea: to one side, there is advocacy for more plant foods (vegetables, fruits, legumes, whole grains, nuts, and seeds); to the other, there is advocacy for more animal foods (meat, butter, cheese, eggs) and more animal fat. I am decisively in the former camp.
What the allowance for doubt tells us is that if, in fact, the evidence is insufficient to be absolutely certain that one of these is right- then we cannot be absolutely certain that the other is right, either. Let’s pretend the playing field is level; let’s give all the same benefits of all the same doubts to all the members of both camps. I am not entirely sure that’s deserved- but let’s toss the benefit of that doubt into the pot as well.
It all leaves you with a choice - now, and whenever you hear the latest “news” about nutrition. You can risk being wrong in one direction, or you can risk being wrong in the other.
Let’s say that those of us recommending more whole plant foods, and a dietary pattern in which they predominate, are wrong. What are you risking by listening to us?
Well, we know that all of the world’s longest lived, most vital peoples discovered to date eat this way. So even if we are wrong about whole foods, mostly plants being best for your health- they are clearly compatible with it, as measured by what matters most: both years in life, and life in years. At worst, you wind up eating in a way that is entirely compatible with the best of health, even if not explicitly the best for health. At worst, you wind up missing out on some foods you might otherwise enjoy (although that’s a minor matter, because over relatively little time, you are apt to learn to love the foods you are with).
That’s it. That’s the consequence of choosing to go with the “more plants” camp, if that camp- my camp- is, in fact, wrong.
What are the alternative risks of listening to the “more meat” camp, if that camp is wrong? Well, none of the longest lived, most vital peoples yet discovered eat meat predominant diets, or diets high in saturated fat. So if this camp is, in fact, wrong- then it’s possible that their advice is actually incompatible with the health outcomes that matter most: longevity, plus vitality. If this camp is wrong, you might be increasing your personal risk of disease and premature death. To be clear, I am not saying (at the moment) this is true; I am simply noting that if the “more meat” crowd CAN be wrong, then this COULD be the implication for your health of listening to them.
But that’s the least of it, really, because if you get coronary disease you will probably find some cardiologist to clean out your arteries; you get to have your disease, and make it chronic, too.
The consensus among environmental scientists about meat and dairy is even greater than that of nutrition scientists. Producing plants to feed animals to produce meat for human consumption uses vastly more water than producing plants for direct human consumption; beef, compared to almost any other food, is literally off the chart (in the company of chocolate). Producing meat, and dairy, makes massive contributions to greenhouse gas emission.
So, unless all of the environmental scientists- experts in everything from life cycle analysis to conservation, sustainable agriculture to biodiversity- are wrong, too, then listening to the “more meat” camp and being wrong means potentially devastating effects on the world’s climate, ecosystems, and aquifers. In contrast, if the “more plants” camp is wrong about the best diet for health, listening to them will almost certainly confer diverse environmental benefit.
And, finally, there is the matter of ethics, decency- and what we ironically call “humane” treatment. If the “more plant” camp is wrong about what’s best for your health, listening to them will nonetheless reduce the cruelty and abuse perpetrated on vast populations of animals that think and feel an awful lot like the dogs, and cats, and horses so many of us love. If, however, you listen to the “more meat” camp and they are wrong, then ever more such animals will be subject to cruelty, abuse, and often traumatic death- in the service of your dietary degradation.
Let’s summarize. If the “more plant” message is wrong, then the worst case scenario is that it’s still compatible with optimal health (just not necessary for it); still massively beneficial to the environment and planet (unless all of the environmental scientists are also wrong); and massively conducive to the kinder, gentler treatment of our fellow creatures (unless…well, nothing. Period).
If the “more meat” message is wrong, then the worst case scenario is that it may be incompatible with optimal health, and listening to it may potentially take life from your years, with or without taking years from your life. Along the way, you will almost certainly be contributing to environmental degradation, aquifer depletion, global warming, and cruelty to animals at an industrial scale.
None of this says that one camp is right and the other wrong. It simply stipulates that if we really have cause to be uncertain about fundamentals of nutrition, then what’s good for the plant-loving goose should be good for the meat-loving gander. Human fallibility is non-denominational.
And, presumably, you- like the rest of us- are not infallible either. So if obligated to eat despite the routinely broadcast doubts about diet and health- perhaps the best you can do is choose how you would rather be wrong.
David L. Katz, MD, MPH, FACPM, FACP, FACLM, is the Founding Director (1998) of Yale University’s Yale-Griffin Prevention Research Center, and current President of the American College of Lifestyle Medicine. He has published roughly 200 scientific articles and textbook chapters, and 15 books to date, including multiple editions of leading textbooks in both preventive medicine, and nutrition. He has made important contributions in the areas of lifestyle interventions for health promotion; nutrient profiling; behavior modification; holistic care; and evidence-based medicine. David earned his BA degree from Dartmouth College (1984); his MD from the Albert Einstein College of Medicine (1988); and his MPH from the Yale University School of Public Health (1993). He completed sequential residency training in Internal Medicine, and Preventive Medicine/Public Health. He is a two-time diplomate of the American Board of Internal Medicine, and a board-certified specialist in Preventive Medicine/Public Health. He has received two Honorary Doctorates.