Dietary Intake of Antioxidants and Risk of Alzheimer Disease

SEVERAL FINDINGS SUGGEST THAT oxidative stress may play an important role in the pathogenesis of Alzheimer disease. First, the brains of patients with Alzheimer disease contain lesions that are typically associated with exposure to free radicals. In addition, oxidative stress in brains of Alzheimer patients is indicated by elevated cerebral levels of endogenous antioxidants that scavenge free radicals. Moreover, in vitro studies suggest that exogenous antioxidants reduce the toxicity of -amyloid in brains of Alzheimer patients. Based on these findings, it has been hypothesized that antioxidants from food may reduce the risk of Alzheimer disease. A previous randomized controlled trial found that patients taking vitamin E supplement had a slower progression of Alzheimer disease than patients taking placebo. It is thus possible that high intake of antioxidants may also prevent the onset of dementia, because antioxidants may reduce neuronal loss due to oxidative damage. Two studies examined the longitudinal relationship between antioxidants from supplements and risk of Alzheimer disease. These studies found conflicting results: vitamin C supplement use was related to lower risk of Alzheimer disease in one study, whereas the other found no association for combined use of vitamin C and vitaminEsupplements. However, studies on supplement use are prone to bias, because people who use supplements may also have more health problems and more health-seeking behavior. In addition, use of supplements is generally of short duration. To date, only 1 study has prospectively examined the association between dietary antioxidants and risk of dementia, and found a reduced risk of dementia associated with increased intake of flavonoids. We investigated whether intake of a range of antioxi-