Antioxidant vitamins may mitigate some of the benefits of exercise, report scientists in Germany (Ristow et al. Proc Natl Acad Sci U S A. doi:10.1073/pnas.0903485106 [published online ahead of print May 11, 2009]).
Exercise improves sensitivity to insulin. But when muscle cells metabolize glucose, “free radicals”—reactive oxygen species (ROS), which can cause cell damage—are produced. However, the researchers reasoned, because reduced mitochondrial metabolism has been linked with type 2 diabetes, ROS generated by exercise also may have a health-promoting effect that antioxidants such as vitamin C or E might undermine.
Stephenson J. Exercise and Antioxidants. JAMA. 2009;301(23):2432. doi:10.1001/jama.2009.820