We recently reported that doctors are recommending that you should stop taking multivitamins. Well, there's more bad news for supplement fans: A new study published in the Journal of Physiology found that taking vitamins C and E may hinder your ability to improve your muscular endurance.
Researchers asked 54 healthy participants (both men and women) to complete an 11-week running-based endurance program. Half of the participants were randomly assigned to take 1,000 mg of vitamin C and 235 mg of vitamin E daily (researchers say that's about the amount found in store-bought supplements). The other half took a placebo pill.
After the 11 weeks, researchers found that the supplement-taking participants showed fewer markers of the production of muscle mitochondria—essentially, the power cells in muscles. Your body produces muscle mitochondria as the muscles grow—so producing more means that you've gained strength, or endurance, in that muscle, and producing less, on the other hand, means that your workout wasn't as effective.
Why the lag in effectiveness? The researchers point to the antioxidants in these vitamin dosages as the culprit in inhibiting muscle-building cells. That's consistent with previous research on antioxidants—they inhibit inflammation, which is what nutritionists celebrate them for. But the flip side of that coin is that they can also inhibit muscle growth.
According to the National Institute of Health's Office of Dietary Supplements, women need just 75 mg of vitamin C and 15 mg of vitamin E daily. And something we've said before and we'll say again: The best way to get your recommended daily dose of almost all vitamins and nutrients is through whole foods.