Effects of grape juice consumption on oxidative stress and inflammation in male volleyball players: A randomized, double-blind, placebo-controlled clinical trial

Introduction: Some foods are also demonstrated benefits, such as anti-inflammatory, antioxidant, and ergogenic activity, similar to that of sports supplements. Grape juice has been considered an important source of poly -phenols and these compounds could promote positive effects to the sports players. In this sense, the objective was to evaluate the effects of purple grape juice consumption on indicators of oxidative stress, inflammation, muscle damage, global histone H4 acetylation levels, and muscle strength and muscle power in volleyball athletes. Methods: This is a randomized double-blind clinical trial in which 12 male volleyball players (16 +/- 0.6 years old) participated in three different moments with match simulation: control (without beverage) (WB), grape juice (GJ) and placebo (PLA) (400 mL/day of grape juice or placebo (maltodextrin) for 14 days in a cross-over model). Before and immediately after each match, blood collection for analysis of indicators of systemic redox status, systemic concentrations of Interferon-gamma (IFN gamma) and Interleukin-4 (IL-4), muscle damage, by Creatine Kinase (CK-NAC) and levels of global histone H4 acetylation were performed, as well as handgrip strength (HG) and lower limb power tests. Results: Consumption of grape juice significantly reduced lipid peroxidation (p = 0.04) and Deoxyribonucleic Acid (DNA) damage (p = 0.01) after the match. IFN-gamma levels, IL-4, CK-NAC, and histone H4 acetylation post-match did not alter with the grape juice consumption. Lower limb power improved after acute exercise in WB and GJ conditions (p < 0.001). Conclusion: In this pilot trial, the intake of grape juice for two weeks seems to reduce the protein oxidation and DNA damage by intermittent physical exercise, without epigenetics influence.