The shared belief, as articulated on the many and growing Web sites dedicated to the practice, is that cooked food is poison — "dead food" — that we primates were never designed to eat. "In nature, all animals eat living foods," wrote T.C. Fry, an early raw-food advocate who nonetheless passed away six years ago at the relatively early age of 70…This health regime goes beyond mere Veganism: For the Rawist, even a simple baked potato has been rendered not only less nutritious, but carcinogenic by virtue of its time spent in an oven.

Pick up an enthusiasts' book on the subject and you will read that the diet can cure a host of ills, from obesity to aging to cancer. But read an article in a publication like the journal of the American Medical Association, you'll be told that any benefits of a raw-foods diet are pure fantasy. Where does the truth lie?

The cornerstone of the "rawist" philosophy is simple: Nature is perfect. Proponents say that raw foods are nutritionally complete, and that cooking food is not only unnatural, but detrimental to its nutritional content. They shun baking, boiling, sauteing, steaming, microwaving, frying and pasteurization—in short, any method of food preparation or processing that requires heat. "If you can't eat a food in its fresh, natural state, you shouldn't be eating it at all" is a popular rawist mantra. "Man is the only animal who cooks his food" is another.