How Not to Get Sick

Hippocrates once said, "Let food be thy medicine and let thy medicine be food," and doctors now believe that ancient Greek healer may have been onto something. We need food for nourishment, of course. Without it, our cells and tissues would wither away from starvation. But what's becoming clearer is that food is more than just fuel. What you eat can determine how elastic your blood vessels are, how easily you resist cancer-causing toxins and whether or not you will barrel down the road toward heart disease.

"There is an overwhelmingly strong database of studies suggesting that the quality of calories we eat has a huge impact on our well-being and our risk of chronic disease and longevity," says Dr. David Ludwig, director of the Optimal Weight for Life Program at Children's Hospital Boston. (Photos: What Makes You Eat More Food.)

But does food have real power to prevent disease? That's the claim behind functional foods — products that are enhanced or otherwise designed to do much more than simply supply us with needed calories and nutrients.

And the early evidence suggests that the kitchen may indeed contain potent disease-fighting agents, just as the medicine cabinet does. In a groundbreaking 2002 study, researchers found that people at risk of diabetes could delay or in some cases even prevent the disease from developing by eating fewer calories, getting them from the right kinds of foods and exercising more than two hours a week. Even more intriguing, the study revealed that people who were genetically predisposed to diabetes benefited most. In essence, diet and other lifestyle factors altered their genetic destiny.

But before you eat to treat, say experts, remember that not every health claim on a label makes the food a functional food — and not all functional foods help prevent or reverse disease. The Food and Drug Administration does not recognize functional foods as a category, which means that a product's promise to control cholesterol, tame inflammation or protect you from fractures may not be supported by studies. Experts don't even agree on the exact definition of a functional food, but many go by the simple guide that it's something that's often good for you to begin with and that has some added benefit not found in the food's natural state. Other-than-butter spreads enhanced with plant oils, for example, qualify as functional foods, since they are less likely than animal fats to contribute to plaques in blood vessels, and the added plant sterols help reduce cholesterol even further. Soft drinks with extra vitamins and minerals don't make the cut, however, since soda isn't nutritious to start with.

It's confusing, yes. But the best advice, according to experts: stick with foods that are naturally nutritious, and consider adding functional foods where you can. You have to eat anyway, so you might as well make it count.