For his last book, the bestselling The Omnivore's Dilemma, Michael Pollan foraged for wild mushrooms and went pig hunting as part of his research on how humans eat. In his latest work, In Defense of Food: An Eater's Manifesto (Penguin Press), he forages through the masses of conflicting scientific research and nutritional advice to hunt for wisdom on how we should eat. His conclusion: "Eat food. Not too much. Mostly plants." He arrives at this prescription not just by hewing closely to every twist and turn of nutritional science but also by looking to culture and tradition—which he thinks often turn out to be the most sensible guides.
Why does nutrition science seem to whipsaw us—something is good for us one day and bad the next?
There's a basic misfit between the way journalists work and the way scientists work: We journalists overvalue changes in conventional wisdom and undervalue anything that confirms conventional wisdom. So, saying "Eat fruits and vegetables" doesn't get as much attention as a major change in saturated fat recommendations. Science is always tentative and iterative, and there's no one answer, just a process.
You write that you were surprised by how shaky the methods of nutritional research are.
I filled out a food frequency questionnaire used in the Women's Health Initiative [asking participants to report the past three weeks'' food and drink consumption]. As soon as people see it, they realize how hard it is to answer accurately. You are expected to answer what sorts of fat are in your meals, and if you go out to eat, as people so often do now, that is impossible. This is a bedrock database used to say what any group of people is eating. And there's nothing we lie more about than food, except maybe sex. I'm not rejecting nutrition science as a worthwhile enterprise, but it's where surgery was in 1650.
So what should people do when they read about a new study?
Read it with skepticism. Take everything as provisional and as interesting, like watching the score in a baseball game. Don't go overboard. Don't eat a bunch of kiwis because a study says they're the new superfood—unless you like them. The latest research shouldn't be your guiding authority on food, because it may well change. If you look at history, the latest nutritional wisdom has often turned out to be not just wrong but dangerously wrong.
A good example is margarine, which was created as a healthy alternative to supposedly unhealthy butter.
Margarine is continually being re-engineered, and we have no idea whether those ways will be healthy. It used to be full of trans fats until we realized those were worse than saturated fats.
You offer some rules for eating. One is to avoid products that make health claims. Why?
In order to make a health claim, you usually have to have a package, which means it's a processed food. Those food companies have big marketing budgets to commission scientific studies. The really healthy foods are whole foods [fruits, vegetables, fish, and other unprocessed foods], which don't come in packages. They're being drowned out.
The public-health crisis we are facing is a direct result of the western diet: lots of refined, processed, and manufactured food, lots of red meat, lots of added fat and sugar, very little whole grains or fruits and vegetables. Without understanding the precise mechanism, we know that the western diet is responsible for probably 80 percent of heart disease, 40 percent of cancer, and most cases of type 2 diabetes. We either need to get used to that as individuals and as a culture—make the seats bigger on airplanes and install dialysis centers on every corner—or we need to resolve to change it. We all have the power right now to change how we eat.