Do vegans actually live longer?

In 1940 the nutritionist and radio personality Dr. Victor Lindlahr published a book entitled, “You are what you eat.” If this were actually the case, then anyone could just go on a high protein diet and develop the physique of an Olympian. It seems that we are all surrounded by recommendations for diets that will cure obesity and all its complications. Since today is National Vegan Day and it seems appropriate to take a look at the claims of veganism.

Veganism is the practice of consuming nothing in the diet that came from an animal source. The Vegan Society was formed in 1944 (George Bernard Shaw was an initial supporter) as a splinter group from the Vegetarian Society, which dates back to 1847. Vegans eliminate milk products and eggs, as well as meats. This differs from vegetarians who don’t eat meat but do consume dairy and eggs.

{mosads}Animal-free diets, in various degrees, have been around for millennia especially in India and among the ancient Greeks. In its stricter forms, ethical vegans will eschew using anything animal derived, including leather or wool. Its most extreme form is probably Jainism whose practitioners seek salvation, in part, by avoiding harm to any living thing and sweep the ground ahead of them as they walk to avoid killing insects.

As nutrition experts, we will leave the spiritual nature of veganism to others and focus on the onslaught of conflicting health claims regarding the beneficial effects of veganism on blood pressure, weight, longevity and just about every other system in our bodies. Unfortunately, most Americans get this information from our least reliable medical news source, the morning talk shows. Spoiler alert. The answer is going to be, “We’re not sure.” Don’t keep reading if you don’t like an honest response.

Despite all the new medications, exercises, diet plans, tummy jigglers and cryotherapies, the prevalence of obesity over the last decade has increased from 34 to 40 percent in adults and from 17 to 19 percent in children. There has been a parallel increase in diabetes; hypertension and all the other complications associated co-morbidities. Strict vegans tend to be thinner than animal eaters. However, we don’t know if they were thinner before they became vegans or if they are intrinsically just better at adhering to any lower calorie diet and would do just as well on a similarly lean low carb or low fat diet.

A recent review of the medical literature regarding different weight loss diets reported that vegans and vegetarians lost more weight. The difference diminished over time suggesting that either the effect is limited or that the research participants just can’t stay on the diet. Compliance with any diet is the key and is one of many difficulties in nutritional research. Imagine participating in a study in which you would need to strictly adhere to a specific randomly assigned diet for 20 years, especially if it wasn’t what you normally eat. Imagine doing that when the food available to you in your local emporia did not cater to that particular diet. Could you really have resisted that candy bar you snuck out of the Halloween stash you bought for the trick-or-treaters last night?

Other health benefits of a vegan diet are equally vague. Some studies report that a vegan diet is beneficial to individuals with type II diabetes while others report that it exerts no health benefits on diabetes risk (though does lower blood pressure).

Biology is complicated and, unlike mice of a specific strain, all humans are not the same. We evolved as omnivores and require certain nutrients that are seriously lacking in a vegan diet. Vegans have an increased frequency of fractures due to inadequate vitamin D (at least drink some almond milk) and may actually increase their risk of cardiovascular disease and neurological disease as a result of low vitamin B12.

So, anyone opting for a vegan diet should probably meet with a nutrition expert who will assess the nutrient availability in the individual diet and how it fits in with other medical issues that each person may have.

To be sure, there is an advantage to being thinner up to a point. But whether or not the vegan diet is the optimal means to achieve this goal is not clear. Like any other weight loss plan, its success is mainly dependent upon compliance and there is no evidence that maintaining a vegan diet is any more likely than other recommendations. A much larger volume of lettuce than pasta can be eaten for the same number of calories. It is possible that effects of filling up the stomach on various gut hormones related to feeding behavior will enhance adherence to a vegan diet, but it is yet to be proven.

Last, but not least, everyone is biologically different. There may turn out to be health benefits from veganism, or at least something close to it, but they remain more theoretical than demonstrated. Benefits may also only apply to some of us with particular metabolic makeups. What’s best for adults may not be best for children. Again, these areas require more research.

The relationship between diet and health is complicated, poorly understood and very poorly reported to the public. But the principle of moderation and a diet mostly of plant sources seems to be a recommendation that has stood the test of time, as have other overall healthful diets that include the occasional egg, piece of chicken, or even a glass of milk. We are not what we eat but the key questions remaining are what should we eat and how can we best achieve that goal.

Dr. Michael Rosenbaum is a professor of pediatrics and medicine at Columbia University Medical Center and a practicing pediatrician in New York. He has spent over 30 years studying obesity and nutrition in adults and children. David Seres M.D. is the director of medical nutrition, associate clinical ethicist and an associate professor of medicine at Columbia University Irving Medical Center and chair elect of the Medical Nutrition Council at The American Society for Nutrition.