Why Vitamins May Be Bad for Your Workout

Many people take vitamins as part of their daily fitness regimens, having heard that antioxidants aid physical recovery and amplify the impact of workouts. But in another example of science undercutting deeply held assumptions, several new experiments find that antioxidant supplements may actually reduce the benefits of training.

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But their bodies had responded quite differently to the training. The runners who had swallowed the placebo pills showed robust increases of biochemical markers that are known to goose the creation of mitochondria, the tiny structures within cells that generate energy, in cells in their bloodstream and muscles. More mitochondria, especially in muscle cells, means more energy and, by and large, better health and fitness. The creation of new mitochondria is, in fact, generally held to be one of the most important effects of exercise.

But the volunteers who had consumed the antioxidants had significantly lower levels of the markers related to mitochondrial creation. The researchers didn’t actually count the specific populations of mitochondria within their volunteers’ muscles cells, but presumably, over time, those taking the antioxidants would see a smaller uptick in mitochondrial density than among those not taking them.

That finding echoes the results of another study of antioxidant supplementation and exercise, also published last year in The Journal of Physiology, in which half of a group of older men downed 250 milligrams daily of the supplement resveratrol, an antioxidant famously found in red wine, and the other half took a placebo. After two months of exercising, the men taking the placebo showed significant and favorable changes in their blood pressure, cholesterol profiles and arteries, with fewer evident arterial plaques.

The men taking the resveratrol were not as fortunate. They had exercised as much as the other men, but their blood pressures, cholesterol levels and arteries had remained stubbornly almost unchanged.

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