It's no contest. Fiber has been shown to be important in the prevention and treatment of certain conditions and diseases. Vegetarians, especially vegans, often have weights that are closer to desirable weights than do nonvegetarians. Vegetarian diets that are low in animal products are typically lower than nonvegetarian diets in total fat, saturated fat, and cholesterol, factors associated with reduced risk of coronary artery disease and some forms of cancer. . . . Lung cancer rates are lower in vegetarians, chiefly because they usually do not smoke, but possibly also because of diet.
Research suggests that vegetarians are also at decreased risk for breast cancer.
Mortality from coronary artery disease is lower in vegetarians than in nonvegetarians. . . . Studies of vegetarians indicate that they often have lower mortality rates from several chronic degenerative diseases than do nonvegetarians. Vegetarian diets are very safe, have real benefits, and generally require very little planning for maximum health. In contrast, diets that include meat must include careful, extremely complex planning to reduce the risks of the most prevalent diseases. For more information, please see the journal article and other ADA literature.