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A–Z of nutritional supplements: dietary supplements, sports nutrition foods and ergogenic aids for health and performance—Part 33
  1. D C Nieman1,
  2. M W Laupheimer2,
  3. M K Ranchordas3,
  4. L M Burke4,
  5. S J Stear5,
  6. L M Castell6
  1. 1Human Performance Laboratory, Appalachian State University, Kannapolis, North Carolina, USA
  2. 2Department of Sport and Exercise Medicine, Queen Mary Hospital, University of London, London, UK
  3. 3Department of Sport, Faculty of Health & Wellbeing, Sheffield Hallam University, Sheffield, UK
  4. 4Australian Institute of Sport, Canberra, Australia
  5. 5Performance Influencers Limited, London, UK
  6. 6Green Templeton College, University of Oxford, UK
  1. Correspondence to L M Castell, Green Templeton College, University of Oxford, Oxford OX2 6HG, UK; lindy.castell{at}

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Introductory Remarks

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 …

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  • Competing interests David C Nieman is on the Scientific Advisory Board for Quercegen Pharma; this research has also been funded by Coca Cola.

  • Provenance and peer review Commissioned; not externally peer reviewed.