Journal Title (Medline/Pubmed accepted abbreviation): Br J Sports Med
Page numbers: 1202-1205
Summary of Background and Research Design
Summary of article: This brief review article summarized existing research findings examining biologic effects of flavonoids and their role in reduction of exercise-induced oxidative stress, inflammation, and immune dysfunction. The first section of this review was devoted to the classification, bioactive properties, dietary intake, and bioavailability of individual flavonoids, such as quercetin, as well as flavonoid mixtures or flavonoid-rich food. The second section outlines the results of 34 major studies on flavonoids and exercise. The majority of studies reported neutral or positive effects of flavonoids and flavonoid-rich nutrients to attenuate exercise-induced oxidative stress and inflammation or delayed onset of muscle soreness (DOMS). Seventeen flavonoid studies reported mixed results for improved performance (aerobic or muscular). Seven flavonoid studies reported neutral effects on immune dysfunction, and 5 flavonoid studies reported mixed results on the risk of upper respiratory tract infection.
Interpretation of findings/Key practice applications:
This review covers aspects of the optimal nutritional strategy to enhance endogenous antioxidant protection during exercise-induced oxidative damage. Most studies analyzed in this short but informative review concluded that both acute and chronic consumption of flavonoids and flavonoid-rich extracts and products before high-intensity exercise can effectively attenuate postexercise inflammation/DOMS and oxidative stress. The most effective and safe ways to boost antioxidant defense mechanisms are likely to involve ingesting flavonoid-rich food and products as opposed to purified flavonoids because of the poor bioavailability and increased risk of exceeding recommended levels. Further research is necessary to determine optimal flavonoid dosing regimens and the role of flavonoid mixtures. Evidence on whether flavonoids are effective in preventing immune dysfunction associated with high-intensity training remains inconclusive and requires further investigation.