A Powerful Antioxidant May Improve Endurance Without Additional Exercise
Quercetin, an antioxidant found in fruits and vegetables , may increase endurance without regular exercise, according to a study funded in part by the U.S. Department of Defense.
The study was published in the June 2009 issue of the International Journal of Sports Nutrition and Exercise Metabolism.
Quercetin is a phytochemical with powerful antioxidant, anti-histamine and anti-inflammatory properties. It is found naturally in the skins of red apples, red onions and grapes and has also been isolated and used as a dietary supplement.
The researchers, lead by Dr. Mark Davis from the University of South Carolina's Arnold School of Public Health, recruited 12 participants for the study. All of the participants were college aged and, while none were athletes, all were healthy and relatively active.
The participants were randomly divided into two groups. One group was given 500 mg of quercetin twice daily dissolved in the fruit drink Tang for seven days. The other group was given Tang that contained a placebo.
After the seven days of treatment, the participants were told to ride stationary bicycles to the point of fatigue.
The researchers measured the amount of time the participants were able to ride the bicycles as well as levels of maximal oxygen uptake (V02max), which is the best known measure of a person's cardiovascular and aerobic endurance.
The participants then received the opposite treatment for another seven days before riding the bicycle to the point of fatigue once again.
The researchers found a 13.2% increase in endurance and a 3.9% increase in VO2max for the participants following the quercetin supplementation.
The study did not look into the mechanisms behind these results, but pre-clinical data suggests these benefits may be due to an increase in mitochondria in brain and muscle cells. Mitochondria are essentially the powerhouse of the cell and are responsible for producing most of its energy.
The researchers have received a grant to determine further potential benefits for quercetin including its potential to reduce the risk of age-related dementia, cancer, diabetes, obesity and cardiovascular dysfunction.