COLUMBIA, South Carolina—Move over acai berry, the newest antioxidant power player may be quercetin. Research out of the University of South Carolina’s Arnold School of Public Health in Columbia shows that quercetin supplementation boosts endurance capacity and maximal oxygen capacity (VO₂max) in healthy, active but untrained men and women.

Quercetin occurs naturally in the skins of red apples, red onions, berries and grapes. The new findings, which appear in the International Journal of Sports Nutrition and Exercise Metabolism,¹ may be just the tip of the iceberg as far as the benefits of quercetin supplementation go.

“If the findings of this study and hypothesized biological mechanisms are confirmed in more rigorous human clinical trials, the implications of this novel nutritional strategy go far beyond improvements in endurance capacity to possible prevention and treatment of metabolic (e.g. diabetes, obesity), cardiovascular and various degenerative diseases of aging in which mitochondrial dysfunction and physical inactivity are hallmarks,” conclude the researchers who were led by J. Mark Davis, PhD, a professor of exercise science at the University of South Carolina’s Arnold School of Public Health in Columbia.

Quercetin increased endurance by over 13%

In the study, 6 participants received 500 milligrams of pure quercetin twice a day in Tang for 7 days, and another 6 drank Tang with placebos for the week. Participants rode stationary bicycles to the point of fatigue after the weeklong treatment. Researchers also tested their additional VO₂max. Next, participants received the opposite treatment for another week before riding the bicycle and undergoing VO₂max testing.

After taking quercetin for 7 days, study participants had a 13.2% increase in endurance and a 3.9% increase in VO₂max.

Less fatigue, more exercise

“While there’s no magic pill to make people get up and move, or to take the place of regular exercise, quercetin may be important in relieving the fatigue that keeps them sedentary and in providing some of the benefits of exercise,” Dr. Davis said. “We believe that this could be a major breakthrough in nutrition.”

Dr. Davis said that the only readily available commercial source of pure quercetin is mixed with tea catechins, which might contribute to the effect.  

Quercetin’s anti-inflammatory properties

There are no studies on how quercetin may affect arthritis, Dr. Davis said. But “the pre-clinical data would suggest that it could be helpful. Theoretically it could reduce inflammation, reduce fatigue, and improve mobility/physical performance,” Dr. Davis told MSKreport.com.

Quercetin reduces inflammation at various steps in the process, including inhibiting NF kappa-B and reducing the inflammatory cytokines like Interleukin (IL)-6, IL-1 and TNF-alpha, he explained.

Going forward, “we are interested in reducing and or replacing some of the nonsteroidal anti-inflammatory drugs that apparently have important side effects with quercetin and/or curcumin,” he said.

Quercetin appears to be safe, and published safety studies report no side effects, according to Dr. Davis.

Reference

1. Davis MJ, Carlstedt CJ, Chen S, et al. The dietary flavonoid quercetin increases VO₂max and endurance capacity. International Journal of Sports Nutrition and Exercise Metabolism [epub ahead of print June 24, 2009].