Your supplement isn’t just worthless—it’s detrimental to performance. A recently published study by the Norwegian School of Sports Sciences shows that taking large doses of vitamins C and E may blunt the effects of endurance training by interfering with cellular adaptations to exercise.
The study tracked 54 athletic men and women participating in an endurance training program over an 11-week period. Subjects received either 1,000 milligrams of vitamin C, combined with 235 milligrams of vitamin E, or a placebo pill. (These dosages are consistent with amounts commonly found in such over-the-counter products as Emergen-C.)
At the study’s conclusion, its researchers noted that the group taking supplements didn’t show any increase in the biomarkers that signal the production of new mitochondria, the power supply for cells. On the other hand, they didn’t experience a decline in actual performance.
While the link between biomarkers and performance is unclear, “antioxidant supplementation has almost always proven either to be ineffective or detrimental,” says Thomas Sherman, an associate professor of pharmacology and physiology at Georgetown University Medical Center. “I can finally sense in the research literature a growing acceptance of the fact that there is little or no evidence that our endogenous mechanisms for dealing with reactive oxygen species needs any dietary assistance.”