Although antioxidants play a role in defending our bodies cells against oxidative stress, research has shown that these substances may not always be beneficial, especially if theyre consumed in larger-than-usual amounts.

Extensive studies have evaluated the effects of antioxidant dietary supplementsparticularly vitamin E and beta-caroteneon chronic diseases associated with aging. In general, except for age-related macular degeneration, there is currently no evidence that antioxidant supplements have a positive impact on these diseases.

Antioxidant supplements may have harmful effects when taken at high doses. In particular, high-dose beta-carotene supplementation can increase the risks of lung cancer and cardiovascular disease. These effects have been seen primarily in people at high risk of these diseases, such as smokers.