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Quercetin was first introduced to our A–Z series in the article on flavonoids.1 In Part 33, the author of the flavonoid review, Dr Nieman, updates this topic. We also cover another intriguing plant-based compound with proposed benefits as an antioxidant and stimulator of mitochondrial biogenesis, resveratrol. Rhodiola rosea, a claimed adaptogen, concludes this issue.
D C Nieman
Epidemiological studies support multiple disease prevention benefits for individuals consuming foods rich in the flavonol quercetin. In vitro and animal studies indicate that quercetin is a strong antioxidant and anti-inflammatory agent, and exerts antipathogenic and immune regulatory influences.2 Quercetin supplementation studies in community-dwelling humans do not reflect these positive benefits, but research is continuing in order to determine the proper outcome measures, dosing regimen and adjuvants that may amplify any perceived bioactive effects of quercetin in vivo.
Quercetin supplementation studies in athletes have focused on potential influences on post-exercise inflammation, oxidative stress and immune dysfunction, illness rates following periods of physiological stress and exercise performance.
Results thus far have been negative for quercetin's countermeasure effects on postexercise physiological stress indicators, such as immune perturbations.3,–,5 However, when quercetin supplementation is combined with other polyphenols and food components such as green tea extract, isoquercetin and fish oil, a substantial reduction in exercise-induced inflammation and oxidative stress occurs in athletes, with augmentation of innate immune function.6
Quercetin exerts strong antiviral activities when cultured with a wide variety …