Consumption of blueberry polyphenols reduces exercise-induced oxidative stress compared to vitamin C

This study examined whether blueberries or, vitamin C consumed for 7 days in a randomized, double-blind, crossover design would attenuate oxidative stress and cytokine changes versus placebo. Nine subjects ran at 70% VO2max in a hyperthermic environment (35degreesC, 70% relative humidity [RH]) until a core temperature of 39.5degreesC was reached, and for an equivalent time and intensity in the two remaining treatments. Blood samples were drawn before exercise and immediately, 15 minutes, and 30 minutes after exercise. Plasma samples were analyzed for F-2-isoprostanes, lipid hydroperoxides, vitamin C, ferric reducing antioxidant potential, urate, interleukin-1ra, interleukin-6, interleukin-8, and interleukin-10. The pattern of change between treatments was significant for lipid hydroperoxides but not for any other marker. Significant correlations were found between 172-isoprostanes, lipid hydroperoxides, ferric reducing antioxidant potential, and urate. This study indicates that blueberry supplementation may be beneficial for athletes exercising in hot environments. (C) 2004 Elsevier Inc. All rights reserved.