Thirty days of resveratrol supplementation does not affect postprandial incretin hormone responses, but suppresses postprandial glucagon in obese subjects

AimsResveratrol, a natural polyphenolic compound produced by various plants (e.g. red grapes) and found in red wine, has glucose-lowering effects in humans and rodent models of obesity and/or diabetes. The mechanisms behind these effects have been suggested to include resveratrol-induced secretion of the gut incretin hormone glucagon-like peptide-1. We investigated postprandial incretin hormone and glucagon responses in obese human subjects before and after 30days of resveratrol supplementation. MethodsPostprandial plasma responses of the incretin hormones glucagon-like peptide-1 and glucose-dependent insulinotropic polypeptide and glucagon were evaluated in 10 obese men [subjects characteristics (meanstandard error of the mean): age 522years; BMI 321kg/m(2), fasting plasma glucose 5.50.1mmol/l] who had been given a dietary supplement of resveratrol (Resvida((R)) 150mg/day) or placebo for 30days in a randomized, double-blind, crossover design with a 4-week washout period. At the end of each intervention period a standardized meal test (without co-administration of resveratrol) was performed. ResultsResveratrol supplementation had no impact on fasting plasma concentrations or postprandial plasma responses (area under curve values) of glucose-dependent insulinotropic polypeptide (11.2 +/- 2.1 vs. 11.8 +/- 2.2pmol/l, P=0.87; 17.0 +/- 2.2 vs. 14.8 +/- 1.6minxnmol/l, P=0.20) or glucagon-like peptide-1 (15.4 +/- 1.0 vs. 15.2 +/- 0.9pmol/l, P=0.84; 5.6 +/- 0.4 vs. 5.7 +/- 0.3minxnmol/l, P=0.73). Resveratrol supplementation significantly suppressed postprandial glucagon responses (4.4 +/- 0.4 vs. 3.9 +/- 0.4minxnmol/l, P=0.01) without affecting fasting glucagon levels (15.2 +/- 2.2 vs. 14.5 +/- 1.5pmol/l, P=0.56). ConclusionsOur data suggest that 30days of resveratrol supplementation does not affect fasting or postprandial incretin hormone plasma levels in obese humans, but suppresses postprandial glucagon responses.