Antioxidants

Dietary antioxidants are compounds in foods that significantly decrease the adverse effects of reactive species (also called free radicals), including reactive oxygen and nitrogen species, on normal physiological function in humans. An imbalance between antioxidant defenses and the production of reactive species is defined as oxidative stress. Oxidative stress has been implicated in the pathogenesis of many age-related degenerative conditions, including Alzheimer's disease, cancer, cardiovascular disease, cataract, diabetes, macular degeneration, and rheumatoid arthritis. Observational studies consistently reveal an inverse relationship between consumption of foods rich in antioxidants and the risk of these chronic diseases. In contrast, randomized clinical trials of selected [Page 68]antioxidants administered as supplements have largely failed to find any health benefits. This entry reviews the mechanisms of action of antioxidants, their interactions ...