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From an exercise perspective, accumulating data in the last decade have indeed demonstrated positive physiological effects of quercetin supplementation on aiding components of training adaptation and reducing symptoms of illness during intensive periods of training. For example, double blind studies have demonstrated that 3 weeks of quercetin supplementation (1 g/day) prior to a 3 day intensive winter cycling training block reduced the incidence of upper respiratory tract infections in the subsequent 2 week recovery period.2
Additionally, 2 weeks of quercetin supplementation has also been shown to improve endurance running capacity, an effect potentially mediated via increased mitochondrial content of skeletal muscle.3 Furthermore, when quercetin is co-ingested with green tea extract and fish oil supplementation, post-exercise inflammation is reduced and markers of immune function are improved in trained cyclists.4
When consumed in supplement form, supplementation of quercetin is deemed medically safe and does not cause any adverse symptoms or harmful physiological effects. Consumption of quercetin with green tea extract has also been shown to enhance bioavailability thus potentially exacerbating its beneficial effects. It is recommended that daily quercetin supplementation is commenced at least 7-14 days prior to the competitive event or intensive training period.
Dr James Morton SENr is a professor of exercise metabolism and nutrition at LJMU and Head of Nutrition for Team Ineos. He has authored over 120 research publications in the fields of sports nutrition, physiology and metabolism, as well as numerous books.
Find out more about Professor James Morton.
Nothing beats a healthy, balanced diet to provide all the nutrients we need. But when this isn’t possible supplements can help. This article isn’t intended to replace
medical advice. Please consult your healthcare professional before trying supplements or herbal medicines.
IntroChun O. K, Chung S. J, Song W. O. Estimated dietary flavonoid intake and major food sources of U.S. adults, The Journal of Nutrition2007;137(5):1244
2Nieman D. C, Henson D. A, Gross S. J. et al. Quercetin reduces illness but not immune perturbations after intensive exercise, Med Sci Sports Exerc.2007;39(9):1561-9.
3Nieman D. C, Williams A. S, Shanely R. A. et al. Quercetin's influence on exercise performance and muscle mitochondrial biogenesis, Medicine & Science in Sport & Exercise2010b;42(2):338-45.
4Nieman et al. 2009. Effects of quercetin and EGCG on mitochondrial biogenesis and immunity, Medicine & Science in Sport & Exercise 41(2), 1467-1475.