Carotene is a precursor to vitamin A, which means that it turns into vitamin A in your body. In fact, carotene's scientific name is Provitamin A. Carotene can be found in most yellow, orange, or red fruits and vegetables, among other foods like seaweed.

Beta-carotene is the most effective and possibly the best-known form of carotene; it also serves as an antioxidant. Signs of a deficiency include deteriorating eyesight, oversensitivity to light, irritated eyes, and various skin disorders.

Go Ask Alice (the advice column, not the book) notes that "beta-carotene along with other phytochemicals (nutrients of plant origin) may be effective against macular degeneration (an eye disease causing blindness), prostate, and other cancers." (