David L. Katz, MD
Photo: Mackenzie Stroh
Q: With so many books and experts recommending vegan diets, I have to ask: How healthy are they?
— Kathy Dise, Cleveland

A: It depends. A vegan diet includes only plant-based foods (no meat, eggs, dairy, or animal-based foods of any kind). It does not, however, require the selection of wholesome foods. After all, doughnuts, French fries, corn chips, and lollipops can qualify as vegan if they contain vegetable oil instead of butter or lard.

But a vegan diet can be among the most healthful ways to eat. Choose plant foods—vegetables, fruits, whole grains, beans, lentils, nuts, and seeds—and you'll get plenty of vitamins, minerals, antioxidants, fiber, and healthy oils while limiting calories, salt, sugar, and harmful fats. You can get all the protein you need from soy and grains combined with beans, nuts, or seeds.

The benefits of a vegan diet extend beyond your own health to that of the planet. Eating plants, rather than feeding plants to animals and then eating the animals, makes much more efficient use of land and water, and produces far less pollution. Eating less meat means fewer industrial farms and fewer animals subjected to harsh treatment. (To learn more about the environmental benefits of being vegan, read The Food Revolution, by John Robbins, and Six Arguments for a Greener Diet, by Michael Jacobson and colleagues at the Center for Science in the Public Interest—download free at cspinet.org . A good resource for doing vegan right is Becoming Vegan, by Brenda Davis and Vesanto Melina.)

Even if you don't want to take the plunge into veganism, it bears repeating that a diet of mostly plants is good for your health. Or you might consider the Mediterranean diet, which includes seafood and some meat and dairy; it has been linked to a longer life span and reduced risk of cancer and heart disease.

David L. Katz, MD, is director of the Yale-Griffin Prevention Research Center and president of the nonprofit Turn the Tide Foundation.