Photo: Bartholomew Cooke
The way its proponents talk, raw food can sound like a magic potion served in a salad bowl. "When I transitioned to an all-raw lifestyle," says Karyn Calabrese, a restaurateur in Chicago, "I felt like I could walk on water. I didn't just stop aging; I began to feel as if I were actually growing younger." The 64-year-old—who could easily pass for 40—is brimming with energy. It's enough to make you want what she's having, which might be a portobello napoleon with "blue cheese" made from cashews, or an avocado puree with wakame and olives wrapped in nori.

A raw diet consists of foods (typically produce, grains, seeds, nuts, and beans) that haven't been heated above a certain temperature, usually somewhere between 104 and 118 degrees. Cooking destroys enzymes that raw foodists believe are essential to human health; without those enzymes, the thinking goes, we're not getting the full, life-supporting benefits of our food.

But this theory overlooks an important fact, says Andrea Giancoli, a spokesperson for the American Dietetic Association. "While it's true that cooking causes enzymes to unravel, the same thing happens to those enzymes as soon as they hit the acidic environment of your stomach." She says raw foodists enjoy so many health perks for a simpler reason: They're eating a lot of plants. Comprehensive lifestyle studies—like the China-Cornell-Oxford Project, which lasted 20 years and followed 6,500 participants—have found that plant-based diets greatly reduce the risk of chronic diseases and conditions.

Still, says Eat to Live author Joel Fuhrman, MD, a specialist in nutritional medicine, there is some magic in raw fruits and veggies. It's not denatured enzymes that worry Fuhrman so much as the loss of vitamins and minerals that occurs and the carcinogens that are produced at high temperatures. He recommends eating a mix of cooked and uncooked produce, because some nutrients (like lycopene in tomatoes and carotene in carrots) are better absorbed after they've been heated. And when you do cook, opt for stewing or steaming. "As a rule," Fuhrman says, "if you cook things at a lower temperature for less time, you'll be moving in a healthy direction."

Four years ago, Gena Hamshaw started shifting toward a mostly raw diet. "Not only did I feel better," says the certified clinical nutritionist, who writes a blog called Choosing Raw, "but, more importantly, I fell in love with the delicious taste of fresh food." Her advice is to start by adding simple uncooked dishes to your regular diet, like vegetable sides and blended soups. "Don't agonize over complicated recipes. Just eat a big chopped salad and you're on your way."

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