Healthy Diets for Healthy Aging

by Nina

Kale by Melina Meza

“One lesson of science, though, is that if the best you can do isn’t good enough to establish reliable knowledge, first acknowledge it — relentless honesty about what can and cannot be extrapolated from data is another core principle of science — and then do more, or do something else. As it is, we have a field of sort-of-science in which hypotheses are treated as facts because they’re too hard or expensive to test, and there are so many hypotheses that what journalists like to call “leading authorities” disagree with one another daily.” —Gary Taubes, New York Times

If you’ve been reading our blog for a while, you may have noticed that something is missing: even though we discuss yoga for healthy eating, we never really define what healthy eating is, and we certainly never provide any specific dietary guidance (and never, ever mention dietary supplements!). But this is no accident. In fact, from the very beginning, we made a policy decision not to discuss diets for healthy aging on the blog. In an early Friday Q&A Brad addressed the issue by saying:

As a scientist who also studies aging, I am especially intrigued about how diet can influence lifespan and health. However, that is not something I want to discuss here, as I am not a nutritionist or trained in this area. It is also something that is hugely complicated, and some of the better scientific controlled studies are not done in humans, but rather in mice or other animal models. For example, I recently attended a symposium in Cape Cod in March on Metabolism and Aging sponsored by Cell Symposia and Elsevier. Data is clearly emerging about how diets high in fat and/or cholesterol are contributing to metabolic dysregulation. But defining the precise molecular pathways that regulate and control our basic metabolism and how diet can contribute to age-related diseases, such as type 2 diabetes, cardiovascular disease, and hypertension, is still in its infancy. At this point I would recommend only common sense. You know, the stuff your grandma was supposed to teach you: eat in moderation and eat your vegetables.

Unfortunately, although it is commonly acknowledged that a “healthy” diet is an important aspect of healthy aging, there is so much controversy about what that healthy diet entails (dairy, for example, is recommended in some diets and not in others) that we decided not to publicly support one theory over another. (I say publicly because obviously all of us make our own dietary decisions in our day-to-day lives.) You see, even with scientists and MDs on board to study the research, we had no real proof that any one theory made more sense than the others. And a recent opinion piece in The New York times confirmed this decision for me. The article Why Nutrition is So Confusing describes the “dysfunctional” research on nutrition as follows:

"The 600,000 articles — along with several tens of thousands of diet books — are the noise generated by a dysfunctional research establishment. Because the nutrition research community has failed to establish reliable, unambiguous knowledge about the environmental triggers of obesity and diabetes, it has opened the door to a diversity of opinions on the subject, of hypotheses about cause, cure and prevention, many of which cannot be refuted by the existing evidence. Everyone has a theory. The evidence doesn’t exist to say unequivocally who’s wrong."

The problem has to do with the particular nature of research on nutrition. The challenges of actually testing out the different theories of what foods and/or diets foster good health and long life are great:

"In nutrition, the hypotheses are speculations about what foods or dietary patterns help or hinder our pursuit of a long and healthy life. The ingenious and severe attempts to refute the hypotheses are the experimental tests — the clinical trials and, to be specific, randomized controlled trials. Because the hypotheses are ultimately about what happens to us over decades, meaningful trials are prohibitively expensive and exceedingly difficult.  It means convincing thousands of people to change what they eat for years to decades. Eventually enough heart attacks, cancers and deaths have to happen among the subjects so it can be established whether the dietary intervention was beneficial or detrimental."

Unfortunately this hasn’t stopped various “experts” from making claims about particular diets and even individual supplements based on less than reliable science. As Taubes says:

Nutritionists have adjusted to this reality by accepting a lower standard of evidence on what they’ll believe to be true. They do experiments with laboratory animals, for instance, following them for the better part of the animal’s lifetime — a year or two in rodents, say — and assume or at least hope that the results apply to humans. And maybe they do, but we can’t know for sure without doing the human experiments.

They do experiments on humans — the species of interest — for days or weeks or even a year or two and then assume that the results apply to decades. And maybe they do, but we can’t know for sure. That’s a hypothesis, and it must be tested.

For now, all we can recommend is, as Brad said, a common sense approach to a healthy diet. So eat moderately, load up on fruits and vegetables, limit the processed foods and try to maintain a balanced diet—we’re leaving it up to you to judge exactly what a balanced diet means to you. But once you make your own decisions about how you want to eat, yoga can help support you. Conscious relaxation practices help foster healthier eating habits by reducing stress eating and building will power. And mindfulness practices help you discover which foods are right for you (some of us have particular allergies, food intolerances or sensitivities), and replace old habits with new, healthier ones.

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