A diet rich in chiles may also prevent or slow the development of some cancers, apparently because of the antioxidant effects of capsaicinoids. Most medical research lumps all capsaicinoids together, but some studies test the effects of one particular capsaicinoid. In one case, for instance, researchers found that dihydrocapsaicin in particular helped guinea pigs' bodies offset the effects of a cholesterol-rich diet. Hungarian medical researcher Albert Szent-Gydrgyi was studying chile peppers in the early 1930s when he discovered and isolated vitamin C, which earned him a Nobel Prize. Chiles, it turns out, contain even more vitamin C per unit weight than oranges do.
Chiles are also high in vitamin A, which, studies suggest, can improve night vision.
Sounds as if, at last, we've found a box to put chiles into. As dazzling as all the medical findings are, an undertone of contradiction accompanies them. In high doses, capsaicinoids can function as a neurotoxin . Other research suggests that, although eating chiles reduces overall cancer risks, too many can actually increase the chances of colon cancer. It also turns out that chiles may be mildly addictive, apparently because they start a chain reaction that stimulates the brain to release endorphins, the body's natural painkillers.