The bottom line:
- Quercetin is a well-known antioxidant and an abundant flavonoid found in several foods derived from plants.
- Laboratory and animal studies have demonstrated quercetin’s antiviral and antibacterial properties.
- Clinical trials have shown that Quercetin can reduce the incidence of viral upper respiratory tract infection such as the common cold following periods of intensive exercise or high mental stress.
Quercetin is a well-known antioxidant and an abundant flavonoid found in several foods derived from plants. Robust scientific evidence has demonstrated Quercetin’s physiological properties including anti-inflammatory, antioxidant, anti-pathogenic and immunomodulatory effects. Having been previously identified as playing an important role in the protection of plants from bacterial and fungal infection; in vitro (i.e. laboratory-based) and animal studies have also demonstrated quercetin’s antiviral and antibacterial properties(1,2).
While research to establish the role of Quercetin in the treatment of viral disease in humans is still in its infancy, preliminary data suggest that Quercetin may be beneficial in the prevention of upper respiratory tract infections. Research has shown that Quercetin can reduce the incidence of viral upper respiratory tract infection in the immediate post-exercise period following intensive exercise and in individuals suffering from high mental stress, conditions in which it is known that immune function is decreased and the incidence of viral infections is higher(3-6).
- Patrick R. FoundMyFitness Topic - Quercetin [Internet]. FoundMyFitness. 2020. Available from: https://www.foundmyfitness.com/topics/quercetin
- Kinker B. Quercetin: A Promising Treatment for the Common Cold. Journal of Ancient Diseases & Preventive Remedies [Internet]. 2014;02(02). Available from: https://www.longdom.org/open-access/quercetin-a-promising-treatment-for-the-common-cold-2329-8731.1000111.pdf
- Heinz S, Henson D, Austin M, Jin F, Nieman D. Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial. Pharmacological Research [Internet]. 2010;62(3):237-242. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/
- Li Y, Yao J, Han C, Yang J, Chaudhry M, Wang S et al. Quercetin, Inflammation and Immunity. Nutrients [Internet]. 2016;8(3):167. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/
- Nieman D, Henson D, Gross S, Jenkins D, Davis J, Murphy E et al. Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise. Medicine & Science in Sports & Exercise [Internet]. 2007;39(9):1561-1569. Available from: https://journals.lww.com/acsm-msse/
- Nieman D, Henson D, Maxwell K, Williams A, Mcanulty S, Jin F et al. Effects of Quercetin and EGCG on Mitochondrial Biogenesis and Immunity. Medicine & Science in Sports & Exercise [Internet]. 2009;41(7):1467-1475. Available from: https://journals.lww.com/acsm-msse/