Create Account | Sign In: Author or Forum

Search Symptoms

Category: Endocrinology | Family Medicine | Internal Medicine | Pathology | Journal

Back to Journal Articles

Antioxidants Block Beneficial Effects of Exercise

Last Updated: May 12, 2009.

Oxidative stress resulting from exercise increases insulin sensitivity and promotes the body's own antioxidant defense, a response that is blocked by taking antioxidants such as vitamin C, according to a study published online May 11 in the Proceedings of the National Academy of Sciences.

TUESDAY, May 12 (HealthDay News) -- Oxidative stress resulting from exercise increases insulin sensitivity and promotes the body's own antioxidant defense, a response that is blocked by taking antioxidants such as vitamin C, according to a study published online May 11 in the Proceedings of the National Academy of Sciences.

Michael Ristow, M.D., from the University of Jena in Germany, and colleagues examined insulin sensitivity in 40 young men (mean age, 25.40 to 27.44 years) before and after four weeks of exercise. Half of the men were previously trained and half were previously untrained, and half of each group was randomly assigned to daily supplements of vitamin C and vitamin E.

The researchers found that insulin sensitivity, as assessed by glucose infusion rates, plasma adiponectin and fasting plasma insulin, increased after exercise, but only in men who did not receive antioxidants. Several markers of insulin sensitivity and defense against reactive oxygen species (both transcription regulators and molecular mediators) were also increased in skeletal muscle after exercise, but again only in men who did not receive antioxidants. Previous training had no effect, according to the study.

"Consistent with the concept of mitohormesis, exercise-induced oxidative stress ameliorates insulin resistance and causes an adaptive response promoting endogenous antioxidant defense capacity," Ristow and colleagues conclude. "Supplementation with antioxidants may preclude these health-promoting effects of exercise in humans."

Abstract
Full Text


Previous: Principles for Effectiveness Research Published Next: Simple Survey Assesses Adherence to Gluten-Free Diet

Reader comments on this article are listed below. Review our comments policy.


Submit your opinion: