Quercetin supplementation reduces upper respiratory tract infections in the fit-over 40 set

September 10, 2010

In middle aged and older subjects, daily supplementation with the polyphenol Quercetin was associated with fewer sick days related to upper respiratory tract infections (URTI) and a reduction in the severity of infections, according to findings published in the journal Pharmacological Research. The researchers were led by Professor David C. Nieman at Appalachian State University. The study involved 12 weeks of supplementation with Quercetin at doses of 500 and 1000 mg/day.

     Upper respiratory tract infections (URTI) are the most common of all human illnesses. Such infections occur in the nose, sinuses, pharynx, larynx, trachea, and bronchi, and are epitomized by the common cold. According to the National Institute of Allergy and Infectious Diseases, the average adult suffers from between two and four colds every year, but children can catch between six and ten. Quercetin is an antioxidant flavonoid found in fruits and vegetables. It has been shown to possess strong anti-viral properties when cultured with target cells and causal agents of URTI.

     The new study aimed to assess the effects of Quercetin on URTI outcomes. The randomized, double-blinded, placebo controlled trial measured URTI rates and severity in a large community group (1002 participants), over a 12 week period. The authors report that physically fit individuals over 40 year of age experienced a 36 % reduction in URTI severity and a 31 % reduction in total URTI sick days when receiving the high dose. The supplement had no effect on infection in younger adults. “These findings are consistent with published studies linking URTI risk to age, gender, and exposure to stressful life events,” wrote the authors. The study is published online ahead of print in the journal Pharmacological Research.