The effect of quercetin on the prevention or treatment of COVID-19 and other respiratory tract infections in humans: A rapid review
Verdict: Current evidence on the efficacy of quercetin supplementation in the treatment and prevention of COVID-19 is insufficient for its clinical recommendation at this time. Quercetin exhibits both immunomodulatory and antimicrobial effects in preclinical studies; however, only three human clinical trials, each with a low risk of bias rating, were identified in this rapid review. One study reported a decrease in incidence of upper respiratory tract infections following a competitive athletic event. A larger community clinical trial reported a benefit in older, athletic adults only.
Adv Integr Med. 2020 Dec;7(4):247-251. doi: 10.1016/j.aimed.2020.07.007. Epub 2020 Jul 30. PMID: 32837891; PMCID: PMC7392107.