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Medicine & Science in Sports & Exercise:
doi: 10.1249/mss.0b013e318076b566
BASIC SCIENCES: Symposium: Exercise, Antioxidants, and Cardioprotection

Quercetin Reduces Illness but Not Immune Perturbations after Intensive Exercise

NIEMAN, DAVID C.1; HENSON, DRU A.1; GROSS, SARAH J.1; JENKINS, DAVID P.1; DAVIS, J. MARK2; MURPHY, E. ANGELA2; CARMICHAEL, MARTIN D.2; DUMKE, CHARLES L.1; UTTER, ALAN C.1; MCANULTY, STEVEN R.1; MCANULTY, LISA S.1; MAYER, EUGENE P.2

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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.

©2007The American College of Sports Medicine

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