We get hyperbolic headlines about nutrition studies almost every week; it’s how we roll. We can come back to the reasons why we roll that way, and who profits from it, some other time.
For now, it’s enough to note that the global spate of headlines saying things like “vegetarian diet raises risk of heart disease and cancer,” allegedly in response to a new study by scientists at Cornell, takes it to a new, absurd, stupefying level. Maybe this is all just tailor-made for April Fools’ Day. The headlines are making fools of the journalists and editors writing them, and anyone reading them. Maybe it’s all a joke. It’s certainly hard to take it seriously.
The study does not report that vegetarianism increases the risk of heart disease, cancer, or any other bad outcome. Nothing of the sort. Not even close.
The study, accessible here for the brave among you, is by some leading experts in fat metabolism at Cornell. The senior author, J. Thomas Brenna, is a friend and colleague known globally for just such expertise. I have written about Dr. Brenna’s work before.
In this instance, the team speculated that human beings might show adaptations to the fats in their diets over time. In particular, they hypothesized that vegetarian populations might display some known genetic variants that make them better at producing the fats they weren’t getting directly from their food.
So, they compared genetic markers in a population of 234 primarily vegetarian Indians, to those in 311 Americans with fairly typical diets, and found, indeed, that the Indians had a higher frequency of genetic mutations that make them good at producing the fats their diet doesn’t provide.
An example? Well, one is that vegetarians are better at converting plant-based omega-3 fat, notably one called ALA, into the long-chain omega-3’s often called “fish oil,” namely EPA and DHA. This is what the authors predicted.
How did headlines about harm emanate from this? Well, the authors also found that among those adapted to the oils and foods of a traditional vegetarian diet, the imbalances of the modern diet might be especially harmful. The study did not suggest that vegetarian diets were harmful. Rather, it showed that traditional vegetarian populations might be especially prone to the harms of the modern diet. This might help explain, for example, why ethnic Indians seem so prone to type 2 diabetes when they transition to a diet of burgers, fries, and soda.
A reasonable take-away, then, might be that traditional, balanced vegetarian diets are an excellent, healthful choice for anyone so inclined, but may be especially important for people from populations that have made that choice for a long time. They have a higher likelihood of being specifically adapted to it.
As for the mechanisms by which the imbalances of oils in the modern diet can conspire against the health of all of us, and perhaps traditional vegetarians even more so, they are featured in prior work by Dr. Brenna and colleagues, and as noted, I cover them, at least nominally, in my prior column on that work.
As for the current study, it looked only at gene frequencies. Not heart disease, not cancer, not death. Despite the insane headlines, the study had nothing to do with death, or disease. It was a study of gene patterns. We already know that good vegetarian diets prevent disease, even reverse it, and are in the mix with the most health-promoting dietary options on the planet. We know they are good for the planet as well. All of that is established. Designing a study to challenge that would be like conducting a study to see if maybe the earth is still flat after all.
As for the general idea that creatures adapt to what they eat, just visit a zoo. It’s on rather flagrant display. Bamboo isn’t very nutritious food, but it works for the pandas. At some level, this new study is simply affirmation that we are creatures, too. We, too, adapt to our diets.
That’s it, folks- really. Traditional vegetarian diets are very good for us, and the typical American diet, very bad for us. The specific contribution of this study is to note that the typical American diet may be especially bad for traditional vegetarians who haven’t evolved defenses against it. They have, in accord with prediction, adapted to thrive on their native diet.
The world, by the way, remains spherical- more or less.
P.S. - I never like to put words in a colleague's mouth. I ran this by Dr. Brenna himself. His reaction, truncated, was: "...terrific, right on..."
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.