Antioxidants and Exercise May Not Mix

Antioxidants are among the most popular of all dietary supplements and include many familiar nutrients like vitamins C and E.  Antioxidants have a wide-range of health benefits that all stem from their ability to  neutralize unstable chemicals  (known as ‘free radicals’)  that damage delicate cellular structures by oxidizing them, just like bleach ruins fabric.  Exercise also has a wide-range of health benefits that stem from the fact that it improves body strength and functions. But paradoxically, exercise and antioxidants may not go well together.

A study conducted at the University of Jena in Germany looked at the effects of vitamin C and E supplementation on some of the metabolic benefits of exercise  in health young men.

So they weren’t looking specifically at things like muscle mass or fat loss. But the parameters they did study –  insulin sensitivity and the body’s ability to increase natural antioxidant mechanisms –  are  ultimately much more important in terms of promoting overall health than having big muscles or being skinny.

Antioxidants are thought to be beneficial because they protect against a kind of ongoing chemical damage that occurs at the cellular level, throughout life, as a result of both natural and un-natural causes. This damage is known as free radical damage or oxidation damage. According to some theories, free radical damage is a major mechanism in the aging process, especially with respect to the gradual deterioration of body structures and functions negatively associated with aging.  Free radical damage is to some extent unavoidable since it arises from normal metabolism, too, but avoidable factors like smoking, alcohol and overexposure to sunlight also induce free radical damage and increase the oxidative load on the body.

Exercise itself also induces a great deal of free radical damage in the body, and in the process of learning to cope with these periodic waves of free radical damage, the body adapts by increasing things like insulin sensitivity and the production of natural antioxidant enzymes.  These adaptations are responsible for the conditioning and metabolic benefits of exercise.

So the study may have been motivated by a question of whether antioxidants interfere with this adaptive process, and in so doing undermine the metabolic benefits of exercise.  The results and the researchers conclusions indicate that they did, with uncertain  implications for the tens of millions using antioxidants in conjunction with an exercise program.

If you’re tempted to stop using antioxidants (or the gym) altogether, we’d urge you to wait until further studies answer the many questions this study raises. Does the effect occur with other antioxidants? What about effects on body composition and muscle mass, are those affected? To what extent is the effect dose-dependent?  Only when these questions are answered can a case be made one way or the other.