Carrots have few rivals when it comes to beta-carotene. A mere half-cup serving of cooked carrots packs a walloping four times the RDA of vitamin A in the form of protective beta-carotene. One raw carrot supposedly contains as much, though it's not clear if all of it's usable by your body. Beta-carotene may ward off cancers of the stomach, cervix, uterus, and the oral cavity, and it helps prevent heart disease due to its antioxidant abilities. The National Cancer Institute is studying the whole family of umbelliferous foods, of which carrots are a member, for protective effects. Recent research results from Harvard University suggest that people who eat more than five carrots a week are much less likely to suffer a stroke than those who eat only one carrot a month