What Is Quercetin?

Quercetin (KWAIR-suh-ten) is a flavonoid, a plant-derived compound found in fruits and vegetables. Flavonoids have generated scientific interest because of their potential beneficial effects on human health, including antioxidant, anti-inflammatory, antitumor, and antiviral activities.

Herbs and botanicals have a long history of traditional medicinal use in many countries. Flavonoids were not discovered until the 1930s, but now more than 4,000 types have been identified. In recent years, these naturally occurring substances have been receiving increased attention by researchers, and quercetin in particular has shown great promise.

Quercetin is widely found in apple skins, berries, tea, and red wine. There has been increasing interest in quercetin in the sports science and athletic communities due to scientific and clinical research results that show quercetin’s antioxidant, anti-inflammatory and other properties are likely to improve mental and physical performance. In addition, emerging evidence suggests quercetin may reduce infection risk during intense physical exercise.

To learn more, click here and read "Quercetin: A Scientific Journey of Discovery"

Quercetin: Myths v. Facts

MYTH: No studies have proven that quercetin can improve athletic performance.

FACT: In recent years, there have been several credible clinical studies that have shown that athletes, as well as untrained individuals, can experience increased endurance by consuming quercetin.

• An independent, randomized, double-blind, placebo-controlled, cross-over study from the University of South Carolina showed that when 12 healthy, active (but not highly trained) men and women consumed 500 mg of quercetin (QU995™) in an enriched drink mix twice daily for 7 days, they experienced a 13.2 percent increase in ride time to fatigue (based on bicycle endurance capacity) and a 3.9 percent increase in VO2max (maximum oxygen consumption).
• An independent, randomized, double-blind, placebo-controlled, crossover study by researchers at Pepperdine University on the effect of FRS (a liquid antioxidant formula containing quercetin) on cycling performance in eleven elite cyclists showed a 3.1% improvement in time to complete a simulated 30km mountainous time trial when subjects consumed FRS for a 3 week period.
• An independent, randomized, double-blind, placebo-controlled, cross-over study from Appalachian State University showed that when untrained males consumed 1000 mg of quercetin each day for two weeks they experienced a statistically significant improvement of 2.9% in 12-minute treadmill time trial performance.

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MYTH: If you want to achieve the optimal benefits from quercetin, you can simply eat quercetin-rich fruits and vegetables.

FACT: While there are many benefits to consuming quercetin-rich foods, you cannot achieve the endurance benefits such as those found in the University of South Carolina, Pepperdine, and Appalachian State University studies through food and diet alone. For example, in the University of South Carolina and Appalachian State University studies, participants consumed 500 mg of Quercetin twice a day. A large red apple contains about 10 mg of Quercetin, so you’d have to eat 100 apples a day to get the same amount of quercetin.

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Click here for all Myths and Facts

An Interview with J. Mark Davis, PhD, FACSM

Dr. Mark Davis discusses animal and human studies with quercetin. Dr. Davis is a Professor and Director of the Exercise Biochemistry Laboratory at the University of South Carolina. He has published more than 110 scientific articles on exercise science.