Could Your Vitamins Be Hampering Your Endurance Training?
If you’re popping vitamin C and vitamin E pills to stay healthy this winter, this might give you pause: A new study in the Journal of Physiology finds that those supplements might reduce the effectiveness of endurance training. (Eep!)
Two caveats right off the bat: This was a small study — the subjects were 54 healthy, young men and women — and we’re bending an in-house rule and reporting on it without having received any response to our requests for comment from the study author (though we’ll keep you posted if we do hear back!).
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Anyway, the study subjects were assigned to either a group that took daily supplements of vitamin C (1000 mg) and vitamin E (235 mg) or a placebo. (Note: Those vitamin dosages are consistent with what you’ll find in typical supplements available in drugstores.) All participants also completed a training program where they did endurance exercise such as running three to four times a week. And they underwent fitness tests, blood samples and muscle biopsies both before and after the 11-week supplement-and-training program.
The results? There was no difference in performance or VO2 max (aka oxygen uptake), but researchers found that an important indicator of muscle power increased only in the placebo group. Specifically, those who took supplements did not show an increase in markers for the production of new muscle mitochondria.
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“Our results indicate that high dosages of vitamin C and E — as commonly found in supplements — should be used with caution, especially if you are undertaking endurance training,” lead author Goran Paulsen said in a release. “Future studies are needed to determine the underlying mechanisms of these results, but we assume that the vitamins interfered with cellular signaling and blunted expression of certain genes.”
Just another reason to get those nutrients from food.