QUERCETIN IS NOT PERFORMANCE ENHANCING

Goulet, E. D., Asselin, A., & Lacerte, G. (2011). A meta-analysis of the effect of Quercetin supplementation on endurance performance and maximal oxygen consumption. Medicine and Science in Sports and Exercise, 43(5). Supplement abstract 1783.

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This study determined the magnitude of the effect of Quercetin supplementation on endurance performance and VO2max using a meta-analytic approach. Database searches and cross-referencing used to locate articles included the following criteria for selection: 1) data necessary to compute the effect estimates and variances; 2) protocols were placebo-controlled, double-blinded; 3) laboratory-based exercise protocols; 4) exercise protocol durations >5 minutes for endurance performance; and 5) studies published in English and in peer-reviewed journals. Exclusion criteria were: 1) Quercetin supplementation <5 days; and 2) research with animals. All endurance performance outcomes were adapted to the same scale and converted to mean changes in power output when necessary. A random-effects model was used to determine the mean weighted summary effects, along with a random-effects meta-regression (method- of-moments) to establish the relationship between fitness level and Quercetin supplementation-induced endurance performance changes. Magnitude-based inferential statistics were also used: the smallest worthwhile % change in VO2max was set at 2.5%, and for half-marathon and marathon-runners and long-distance cyclists the changes in power output were set at 2.15, 2.7, and 1.6%, respectively.

Ten research articles were located providing four (VO2max) and nine (endurance performance) effect estimates from four and six research articles meeting the inclusion criteria. Supplementation duration was 21±18 days (endurance performance) and 18±23 days (VO2max), with a daily amount of Quercetin of 1000 mg. For endurance performance, mean exercise duration was 82±87 min. Quercetin supplementation increased mean power output by ~0.73% and VO2max by ~2.06, compared with the placebo. The meta-regression established no relationship between the changes in endurance performance and VO2max. Under real-world conditions, the effect of Quercetin supplementation on VO2max half-marathon, marathon and long distance cycling performances is very likely to be trivial at best.

Implication. Quercetin supplementation (1000 mg/day) for 18-21 days does not provide an endurance performance advantage or incur a meaningful VO2max change in real-world conditions.

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