Wednesday, July 24, 2013
Resveratrol and exercise: a good thing or bad?
An article just out this week suggests that resveratrol actually cancels the beneficial effects of exercise in older men. This widely cited study, not yet even in print, was a randomized prospective clinical trial in which healthy but inactive men were placed on an exercise program and given either a 250 mg resveratrol supplement or placebo. Exercise tolerance (measured by maximum oxygen uptake), improved cholesterol profiles, and blood pressure indicators in a group of men average age 65 were all improved after 6 weeks in the placebo group as compared to those taking resveratrol , who had no significant changes. This runs counter to expectations from several previous studies (mostly on mice) that suggested the opposite. Resveratrol has even been touted as a performance-enhancing supplement!
This is one reason why use of supplements based primarily on animal studies is problematic; when tested in humans, data may be contradictory. The real questions are how and why such different effects can occur. One explanation is a phenomenon called hormesis. This is sort of the inverse of the J-shaped curve of healthy drinking, with low concentrations yielding a neutral or negative effect, increasing doses having a greater effect up to a point, then adverse or even opposite effects at doses above that. It is important to recognize that paradoxical effects can occur at concentrations either low or high, and the optimal range (in pharmacology called the “therapeutic window”) may vary with different types of tissues. So the best dose for exercise training (if any) could be entirely at odds with what brain cells or blood vessels respond to. Also called a “biphasic response,” the effect has been seen in cancer cell cultures, osteoporosis, and other systems.
All this presumes of course that resveratrol in supplement form is evenly absorbed and distributed, which seems also to be highly variable. Even if resveratrol enhanced the beneficial aspects of exercise in men, there are the hormetic estrogen properties to sort out. If all this is enough to drive one to drink, I suggest a glass (or 2 at the most) of red wine.