Workout supplements aren’t just for serious athletes or guys who hang around the weight room. The American College of Sports Medicine estimates that 40-50 percent of recreational athletes take vitamin and mineral supplements to help improve exercise and training outcomes. The most common: antioxidants including vitamins A, C and E and the mineral selenium. But does mixing antioxidants and exercise help your goals, or hinder them?

First, what’s an antioxidant?

Antioxidants are substances that help fight free radicals, a byproduct of oxidation, a normal chemical process that occurs in the body every day after exposure to pollution, cigarette smoke, stress, or in this case, exercise. Free radicals have been linked to many chronic diseases, including cancer and heart disease. Research suggests that a diet rich in foods naturally high in antioxidants, including fruits, vegetables and whole grains, is associated with better health outcomes.

So what’s the deal with antioxidants and exercise?

Working out puts stress on the body and can damage muscle tissue, leading to an increase in free radicals. Research on the effects of antioxidant supplements — such as vitamins A, C and E — on muscle damage shows that these supplements may decrease oxidative stress. This has lead many in the exercise community to believe that antioxidant supplementation post-workout may result in quicker recovery and less muscle soreness. 

But…

Two recent studies suggest that antioxidant supplementation after exercise could delay recovery and may even lead to muscle injury.

Please explain.

A 2014 study looked at 54 healthy men and women, who had been running or cycling recreationally between one and four times per week for 6 months, and divided them into two groups. One group received daily supplementation with 1,000mg of Vitamin C —the same amount found in one packet of Emergen-C— and 235mg of Vitamin E, while the other group received placebo pills.  The study found that those who received the antioxidants had smaller endurance gains compared to those who received the placebo.

A similar response was shown in a study that looked at the effect of antioxidant supplements — same dosage of vitamins C & E as the study above — after 10 weeks of progressive strength training. At the end of the study, all 32 participants showed an increase in muscle size, but the antioxidant group made fewer strength gains than those who received the placebo.

What’s the deal?

Researchers aren’t sure why antioxidants affect your body’s reaction to cardio exercise or weight training, but they suspect that there may be a difference between free radicals generated by exercise and those generated by, say, pollution. The latter is definitely harmful, but it may be that exercise free radicals are actually essential to improving your fitness level.

So, to supplement or not to supplement?

I vote no. While these studies were small, there doesn’t appear to be any benefit to supplementing in an attempt to maximize your workout gains. The best advice: focus on consuming a varied diet rich in fruits, vegetables, whole grains, legumes, nuts and seeds, and leave those antioxidant bottles on the shelf.