Skip the vitamins?

From the NY Times:

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.

That is the message of a surprising new look at the body’s reaction to exercise, reported on Monday by researchers in Germany and Boston.

Exercise is known to have many beneficial effects on health, including on the body’s sensitivity to insulin. “Get more exercise” is often among the first recommendations given by doctors to people at risk of diabetes.

...

The Jena team 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,” Dr. Ristow 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 The Proceedings of the National Academy of Sciences.

The effect of vitamins on exercise and glucose metabolism “is really quite significant,” said Dr. C. Ronald Kahn of the Joslin Diabetes Center in Boston, a co-author of the report. “If people are trying to exercise, this is blocking the effects of insulin on the metabolic response.”

The advice does not apply to fruits and vegetables, Dr. Ristow said; even though they are high in antioxidants, the many other substances they contain presumably outweigh any negative effect.

I don't take handfuls of vitamins like I used to, but can't quite wrap my head around skipping them entirely.