jupiterimages

There may be a new antioxidant powerhouse poised to enter the realm of natural endurance enhancers. Quercetin, a natural flavonoid found in red apples, red onions, berries, cabbage, broccoli and tea (green and black), may be able to boost exercise endurance by 13 percent, according to a new study published in the International Journal of Sports Nutrition and Exercise Metabolism.

Twice a day, 12 fit college students with an average age of 23 were given either a placebo or a 500 mg quercetin table dissolved in Tang, which apparently masks the taste, texture and color of quercetin quite well. Who knew? After seven days, researchers calculated how long it took for each student to become fatigued on a stationary bike. The placebo and study groups were then swapped, and the process repeated.

Compared to their starting endurance capacity, the participants who were given quercetin showed a 13 percent increase in ride time before becoming too tired to continue.

Researchers posit that quercetin's ability to increase endurance may mimic the effects of a psychostimulant, such as caffeine, due to an ability to block receptors in the brain, which can delay fatigue and increase dopamine activity. In addition, the antioxidant qualities of quercetin may also contribute to a person's ability to exercise longer.

The downside? It seems that while untrained participants (such as the students who were studied) may receive a substantial endurance push from quercetin, highly trained athletes may not achieve as much of a benefit because they may have "already reached a ceiling with respect to antioxidant...capacity."

While more studies need to be done to assess quercetin's effects on endurance in humans, there are already quercetin supplements lining the shelves of your nearest nutritional center.

"People are always looking for the magic bullet and the quick fix," says Nancy Clark, M.S., R.D., sports nutritionist and author of "Nancy Clark's Sports Nutrition Guidebook." "It's really naïve to think that any pill can replace a whole food. It's a preliminary study and certainly worth of exploring more, but until the facts come out, keep eating your apples."