[troutman]

Antioxidants and Exercise: More Harm Than Good?

http://www.sciencebasedmedicine.org/...arm-than-good/

Multivitamin supplementation has been getting a rough ride in the literature, as evidence emerges that routine supplementation for most is, at best, unnecessary. Some individual vitamins are earning their own unattractive risk/benefit profiles: Products like folic acid, calcium, and beta-carotene all seem inadvisable for routine supplementation in the absence of deficiency or medical indication. Vitamin E, already on the watch list, looks increasingly problematic, with data recently published confirming the suspected association of supplementation with an elevated risk of prostate cancer.

Reading through the vitamin posts here at SBM, one issue comes through repeatedly: The danger of assuming therapeutic benefits in the absence of confirmatory evidence. Vitamin supplement have the patina of safety and of health, a feature that’s reinforced when you purchase them: You don’t need a prescription, you don’t get counseled on their use, and there isn’t a long list of frightening potential side effects to accompany the product. You can pull a bottle off the shelf, and take any dose you want. After all, how harmful can vitamins be when you can buy 5 pounds of vitamin C at a time, or vitamin E capsules in a 1000-pack? But the research signals seem to be getting stronger, and most are pointing in the same direction: what we though we knew about antioxidants was based on simplistic hypotheses about nutrition and health. And while we thought we were doing ourselves good with antioxidant supplements, we may have been doing harm.

In light of what we know about antioxidants and exercise, the trend in the data is strongly suggestive of zero benefit, at best, with the real possibility that there may be negative consequences to supplementation. Overlay the epidemiologic evidence that looks at mortality, cancer, and other outcomes, and the attractiveness of antioxidant supplements drops even further. The best advice for those that exercise seems to be to focus on consuming a diet rich in fruits and vegetables, and leaving the antioxidant bottles on the shelf. There appears to be little that is complementary about them.