By Margarita Nahapetyan
Quercetin, a powerful antioxidant and anti-inflammatory compound that is commonly found in the skin of some fruit and vegetables, could improve endurance in healthy, active people without regular exercise training, claims a new study.
The scientists at the University of South Carolina's Arnold School of Public Health, discovered that quercetin supplementation - available in FRS Healthy Energy products - significantly improves endurance capacity as well as maximal oxygen capacity (VO2max) in healthy but untrained men and women, and also prevents or treats a number of diseases and health-related conditions.
Quercetin is a kind of plant pigment which is known as a flavonoid and is found naturally in red wine, apples, red onions, berries and other foods. In general, the potential of flavonoids is to produce health benefits and quercetin appears to be no exception. In some cases, it is used to treat the symptoms of prostatitis, and it is also being examined for prevention of cancer, allergies, glucose absorption in diabetics, childhood asthma, and the lung condition sarcoidosis.
For the new study purposes, the investigators involved 12 volunteers, who were randomly assigned to two treatment groups: the participants in one group were given 500 milligrams of quercetin twice a day in Tang for a period of one week. The other group of participants received Tang in combination with placebos. At the end of each week, the experts measured maximal aerobic capacity (VO2max), a measure of fitness, and time-to-fatigue on a training bike, a measure of endurance.
The results revealed that when compared with the control group, VO2max in the quercetin treatment group increased by 3.9 per cent. This benefit was roughly identical to that gained by runners who were taking part in altitude training, said Dr. J. Mark Davis, director of the exercise biochemistry laboratory at the University of South Carolina's department of exercise science and a principal author of the study.
The study also found that there was a 13.2 per cent increase in the time to fatigue when riding the training bike at 75 per cent of maximal aerobic capacity. "If you translate that into some sort of race situation, that is almost always going to be the difference between almost first and last place. That is a big difference," Dr. Davis said. The expert added that it is very unlikely that such a benefit could be achieved just through diet. A person would need to consume approximately 100 apples on a daily basis in order to reach the dose of quercetin used in the study.
If this mechanism is being supported, Dr. Davis continued, the new findings could have implications beyond physical activity for diseases characterized by mitochondrial deficiency or dysfunction, such as Alzheimer's disease and diabetes. Researchers said that quercetin also appears to have beneficial properties to fight inflammation, which has been associated with health-related conditions, such as colon cancer and heart disease. Other possible mechanisms, according to the study authors, include the antioxidant effect on fatigue and the caffeine-like psychostimulant effect. Quercetin blocks adenosine receptors in the brain, which leads to an increased dopamine activity.
Dr. Davis and his research team have recently received a National Institutes of Health grant to investigate on quercetin's effects on colon cancer and there are oter future studies pending that involve breast cancer.
The study appears in the August issue of the International Journal of Sports Nutrition and Exercise Metabolism. The study was partially funded by the Department of Defense (DOD).