A group of organic or inorganic substances capable of preventing the genotoxic and carcinogenic effects of free-radical compounds. Antioxidants bind to and neutralize ('scavenge') free radicals, thereby transforming them into non-toxic compounds and blocking their genotoxic and carcinogenic effects. This class of agents includes the vitamins C and E, the carotenoids, and selenium. Organic antioxidants are found in high concentrations in fruits, seeds and vegetables. (NCI04) [ ]