Effects of chronic resveratrol supplementation in military firefighters undergo a physical fitness test – A placebo-controlled, double blind study

•Firefighters were supplemented with resveratrol (100 mg) and applied a fitness test.•RES increased glucose and triglycerides in firefighters after the fitness test.•IL-6 and TNF-α were decreased in the RES group after the fitness test.•Fitness test applied was not sufficient to challenge the antioxidant defense systems.•100 mg of RES for three months did not induce significant effects.

PurposeThe purpose of this study was to determine the plasma metabolic response and certain indicators of oxidative stress (antioxidant system and oxidative stress biomarkers) in plasma and erythrocytes of Brazilian military firefighters supplemented or not with resveratrol (RES) for 90 days (100 mg/day). The analyses were performed before and after a typical physical fitness test (FT) used to induce oxidative stress.Methods/ResultsIn this placebo-controlled double-blinded study, we observed that RES supplementation did not present hepatic consequences compared with the placebo group following analysis of AST, ALT and GGT plasma activities. Plasma glucose and triglycerides levels were increased after the FT in firefighters supplemented with RES but were not elevated at baseline. Neither total nor cholesterol fractions were modified by RES supplementation. CK levels were increased after the firefighters performed the FT; however, no differences were determined between the placebo and RES groups. Ferric-reducing ability of plasma as well as uric acid was increased after the FT, but was not modified by RES supplementation. Plasma oxidative stress biomarkers, such as thiol content, 8-isoprostane and 8OHdG, showed no modifications, while IL-6 and TNF-α were decreased in the RES group after the FT. Among antioxidant enzyme activities determined in erythrocytes from the firefighters, only GPx activity was reduced by RES supplementation both before and after the FT.ConclusionIn summary, the most pronounced effect of RES supplementation is its anti-inflammatory effect, which reduced IL-6 and TNF-α level. The FT applied to Brazilian military firefighters was not sufficient to challenge the antioxidant defense systems, and, therefore, 100 mg of RES for three months did not induce significant effects.