Intragastric administration of the bitter tastant, quinine, lowers the glycemic response to a nutrient drink without slowing gastric emptying, in healthy men.

Abstract

Gastric emptying and the release of gastrointestinal (GI) hormones are major determinants of postprandial blood glucose concentrations and energy intake. Preclinical studies suggest that activation of GI bitter taste receptors potently stimulates GI hormones, including glucagon-like peptide-1 (GLP-1), thus, may reduce postprandial glucose and energy intake. We evaluated the effects of intragastric quinine on the glycemic response to, and gastric emptying of, a mixed-nutrient drink, and on subsequent energy intake, in healthy men. The study consisted of two parts; part A included 15, and part B 12, lean men (aged 26±2 years). In each part, participants received, on 3 separate occasions, in double-blind, randomized fashion, intragastric quinine (275 mg or 600 mg), or control, 30 min before a mixed-nutrient drink (part A), or before a buffet-meal (part B). In part A, plasma glucose, insulin, glucagon and GLP-1 concentrations were measured at baseline, after quinine alone, and for 2 h following the drink. Gastric emptying of the drink was also measured. In part B, energy intake at the buffet-meal was quantified. Q600 and Q275 alone stimulated insulin modestly (P<0.05). After the drink, Q600 and Q275 reduced plasma glucose and stimulated insulin (P<0.05), Q275 stimulated GLP-1 (P<0.05), and Q600 tended to stimulate GLP-1 (P=0.066) and glucagon (P=0.073), compared with control. Quinine did not affect gastric emptying of the drink or energy intake. In conclusion, in healthy men, intragastric quinine reduces postprandial blood glucose and stimulates insulin and GLP-1, but does not slow gastric emptying, or reduce energy intake, under our experimental conditions.