are antioxidants helpful for disease prevention?

free radicals are produced continuously in the cells as part of normal cellular function, however excess production might play a role in pathophysiology of many disease conditions, including cancer, alzheimer's disease, atherosclerosis and some of the drug-induced toxicity. many basic research studies and observational epidemiologic studies in human suggest that antioxidants can prevent oxidative damage. however, this is still a controversial issue because the results of clinical trials have been inconsistent. this article provides a brief overview of some of the diseases which are associated with free radicals, then discusses the roles of some of dietary antioxidant supplements in disease prevention, with particular reference to the findings of latest clinical trials.