disorders of nutrition
Vitamins and Minerals
Antioxidants
Some vitamins (such as vitamins C and E) and minerals (such asselenium) act as antioxidants, as do other substances in fruits and vegetables (such as beta-carotene). Antioxidants protect cells against damage by free radicals, which are by-products of the normal activity of cells. Free radicals readily participate in chemical reactions—some useful to the body and some not—and are thought to contribute to such disorders as heart and blood vessel disorders and cancer. People who eat enough fruits and vegetables, which are rich in antioxidants, are less likely to develop heart and blood vessel disorders and certain cancers. However, whether these benefits are due to antioxidants, other substances in the fruits and vegetables, or other factors in people's diet and lifestyle is not known; also, taking antioxidant supplements has not been shown to prevent disease or mortality and sometimes can cause harm. 