It almost seems as if the faddish claims of nutritional science have an inverse relationship with reality. If a nutrient is supposed to be good for us, chances are that later research will contradict the claim. Here’s Michael Pollan in the Times Magazine:
Last winter came the news that a low-fat diet, long believed to protect against breast cancer, may do no such thing — this from the monumental, federally financed Women’s Health Initiative, which has also found no link between a low-fat diet and rates of coronary disease. The year before we learned that dietary fiber might not, as we had been confidently told, help prevent colon cancer. Just last fall two prestigious studies on omega-3 fats published at the same time presented us with strikingly different conclusions. While the Institute of Medicine stated that “it is uncertain how much these omega-3s contribute to improving health” (and they might do the opposite if you get them from mercury-contaminated fish), a Harvard study declared that simply by eating a couple of servings of fish each week (or by downing enough fish oil), you could cut your risk of dying from a heart attack by more than a third — a stunningly hopeful piece of news. It’s no wonder that omega-3 fatty acids are poised to become the oat bran of 2007, as food scientists micro-encapsulate fish oil and algae oil and blast them into such formerly all-terrestrial foods as bread and tortillas, milk and yogurt and cheese, all of which will soon, you can be sure, sprout fishy new health claims.
Pollan’s article is a persuasive takedown of “nutrionism,” which he defines as an ideology built around “the widely shared but unexamined assumption is that the key to understanding food is indeed the nutrient.” The problem with this approach is that it involves breaking whole foods apart, until the carrot is nothing but an assemblage of different nutrients, vitamins, and minerals. Unfortunately, nutrionism is too often depends upon shoddy science, and ends up causing Americans to indulge in one food fad after another.
So why does nutrionism endure? Pollan blames the scientific process:
Because a nutrient bias is built into the way science is done: scientists need individual variables they can isolate. Yet even the simplest food is a hopelessly complex thing to study, a virtual wilderness of chemical compounds, many of which exist in complex and dynamic relation to one another, and all of which together are in the process of changing from one state to another. So if you’re a nutritional scientist, you do the only thing you can do, given the tools at your disposal: break the thing down into its component parts and study those one by one, even if that means ignoring complex interactions and contexts, as well as the fact that the whole may be more than, or just different from, the sum of its parts. This is what we mean by reductionist science.
Scientific reductionism is an undeniably powerful tool, but it can mislead us too, especially when applied to something as complex as, on the one side, a food, and on the other, a human eater. It encourages us to take a mechanistic view of that transaction: put in this nutrient; get out that physiological result.
Needless to say, Pollan takes issue with this reductionist approach and shows, in study after study, that nutrient-based nutrition is bad science. It relies on medical oversimplifications and faulty longitudinal studies. It has helped to create a food industry that is making us fatter, sicker and less satisfied with dinner. So what’s the alternative? Pollan argues for the de-medicalization of food. He begins the essay with the secret of healthy eating:
Eat food. Not too much. Mostly plants.
PS. For those interested in the shoddiness of most nutrionism, you might also want to check out this book.