A Word About Antioxidants
Oxygen is a highly reactive molecular component that is important for metabolism, but also produces damage to other complex molecular structures like DNA, proteins and lipids. In chemistry terms, when electrons are transferred from one molecule to an oxidizing agent, an oxidation reaction has occurred and often can produce free radicals. Free radicals are highly reactive and usually have a free electron that will quickly form a new reaction with other molecules, often resulting in cellular damage. Antioxidants are molecules that slow or prevent the oxidation reaction. Vitamins C and E, glutathione, phials, polyphenols, the red wine molecule called resveratrol and many other substances are antioxidants.
Oxidation reactions are believed to occur in neurodegenerative disease, stroke, coronary artery disease and cancer, but it is not yet clear whether the oxidative stress is a cause or a result or simply a concomitant feature of these diseases. The clinical trial data has been far less than reassuring, with the largest recent clinical trial showing no benefit and possible harm due to excess antioxidant supplements (Bjelakovic, G. Journal of the American Medical Association. 2007; volume 297, page 842-857).
Indirect evidence suggests antioxidants may be an important and useful nutritional supplement to prevent disease, but we have not determined how to use them and in what doses, strengths and combinations to be successful. A review study in Public Health Nutrition in 2004, volume 7, page 407-422 by Stanner and Colleagues, lays out the epidemiological evidence for the antioxidant hypothesis and notes that people who eat fruits and vegetables have a lower risk of heart disease and some neurological diseases and there is suggested similar benefits with some types of cancer. These fruits and vegetables are excellent sources of antioxidants, but in the clinical trials to date antioxidant supplements have demonstrated no clear beneficial effect on the risk of these chronic diseases. Studies of vitamin E, vitamin C, beta carotene, green tea and Jiaogulan have failed to prove the hypothesis that antioxidant supplements could prevent disease. Some large meta-analysis trials have actually shown there may be an increased risk of mortality and colorectal cancer with antioxidant supplements, specifically vitamin E.
The bottom line is that laboratory and basic science research on cellular damage and DNA cell wall and protein disruption due to oxidation continues to spur efforts to find antioxidant supplements that may improve health or prevent disease. There is a logic to this science that has, this far, not been born in the sort of clinical trials we would find convincing. Nonetheless, there is indirect evidence that a healthy range of nutrients, which do contain natural antioxidants, including fruits, vegetables, whole grains, legumes, teas and red wine may contribute to reduce the risk of chronic diseases including cardiovascular disease and cancer. So, as of today, while there is interest, hope and some indirect evidence, there is no clear cut advice I can give to recommended particular antioxidant supplements, but the advice to enjoy the healthy range of whole grains, fruits, vegetables, legumes and even a bit of dark chocolate and red wine now and then, remain as strong as ever.