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Randomized Controlled Trial
. 2007 Sep;39(9):1561-9.
doi: 10.1249/mss.0b013e318076b566.

Quercetin reduces illness but not immune perturbations after intensive exercise

David C Nieman  1 , Dru A Henson, Sarah J Gross, David P Jenkins, J Mark Davis, E Angela Murphy, Martin D Carmichael, Charles L Dumke, Alan C Utter, Steven R McAnulty, Lisa S McAnulty, Eugene P Mayer
Affiliations
Randomized Controlled Trial

Quercetin reduces illness but not immune perturbations after intensive exercise

David C Nieman et al. Med Sci Sports Exerc. 2007 Sep.

Abstract

Purpose: To investigate the effects of quercetin supplementation on incidence of upper respiratory tract infections (URTI) and exercise-induced changes in immune function.

Methods: Trained male cyclists (N=40) were randomized to quercetin (N=20) or placebo (N=20) groups and, under double-blind procedures, received 3 wk quercetin (1000 mg.d(-1)) or placebo before, during, and for 2 wk after a 3-d period in which subjects cycled for 3 h.d(-1) at approximately 57% Wmax. Blood and saliva samples were collected before and after each of the three exercise sessions and assayed for natural killer cell activity (NKCA), PHA-stimulated lymphocyte proliferation (PHA-LP), polymorphonuclear oxidative-burst activity (POBA), and salivary IgA output (sIgA).

Results: Pre- to postexercise changes in NKCA, PHA-LP, POBA, and sIgA did not differ significantly between quercetin and placebo groups. URTI incidence during the 2-wk postexercise period differed significantly between groups (quercetin=1/20 vs placebo=9/20, Kaplan-Meier analysis statistic=8.31, P=0.004).

Conclusion: Quercetin versus placebo ingestion did not alter exercise-induced changes in several measures of immune function, but it significantly reduced URTI incidence in cyclists during the 2-wk period after intensified exercise.

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Comment in

  • What is a true placebo?
    Goldfarb AH. Goldfarb AH. Med Sci Sports Exerc. 2008 Apr;40(4):775; author reply 776. doi: 10.1249/MSS.0b013e318164bceb. Med Sci Sports Exerc. 2008. PMID: 18347475 No abstract available.

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