Vitamins Found to Curb Exercise Benefits

If you exercise to improve your metabolism and prevent diabetes, you may want to avoid antioxidants like vitamins C and E.

Researchers found that in the group taking the vitamins there was no improvement in insulin sensitivity and almost no activation of the body’s natural defense mechanism against oxidative damage.

The reason, they suggest, is that the reactive oxygen compounds, inevitable byproducts of exercise, are a natural trigger for both of these responses. The vitamins, by efficiently destroying the reactive oxygen, short-circuit the body’s natural response to exercise.

“If you exercise to promote health, you shouldn’t take large amounts of antioxidants,” researchers said. A second message of the study, he said, “is that antioxidants in general cause certain effects that inhibit otherwise positive effects of exercise, dieting and other interventions.” The findings appear in this week’s issue of Proceedings of the National Academy of Sciences.

The advice does not apply to fruits and vegetables, according to researchers. Even though they are high in antioxidants, the many other substances they contain presumably outweigh any negative effect.

Steve - it is ridiculous that this study was structured the way it was and even more ridiculous that the media would pay so much attention to it, given how tiny the subject size was (39 men).

I would never put an “untrained” person, no matter what their BMI or age, into a program that requires 85 minutes of exercise 5 days per week for 4-weeks, as required in this study. The body needs to accommodate an increase in physical activity to build up its endogenous antioxidant defenses to the anticipated increase in ROS. There are far more nutrients and phytochemicals found in the diet and available supplements and antioxidant-rich foods and juices that would be needed to anticipate the degree of oxidative stress an individual would experience with such an exercise program (as opposed to the 1000 mg vitamin C and 400Iu vitamin E they received).

Athletic clubs that sell memberships have long realized that individuals who sign up and begin at an intense level of exercise can feel defeated due to the side effects they experience in the first month and for this reason often stop their exercise program and revert to a more sedentary lifestyle.

Skeletal muscle biopsies were obtained from the right vastus lateralis muscle of study subjects. But some of the data is missing for a number of subjects, and reported as such by the authors.

The authors noted that biopsies for the ‘early’ time-point were only obtained from five people in the vitamin group, and four in the placebo group. Yet the authors conclude a “strong induction of PGCl-alpha, PGCl-beta, and PPAR-gamma expression in skeletal muscle following 4 weeks of exercise training in previously untrained, antioxidant naïve individuals” and “markedly reduced exercise-related induction” in those taking antioxidants, based on these limited number of biopsies.

In addition, the authors flippantly say antioxidant-rich fruits and vegetables are not an issue. How do they know this without doing the research?