It is thought that diets high in dietary fibre are associated with reduced risk for type 2 diabetes, at least in part because the short-chain fatty acids (SCFAs) produced during the colonic fermentation of fibre beneficially influence circulating concentrations of free-fatty acids (FFAs) and gut hormones involved in the regulation of blood glucose and body mass. However, there is a paucity of data showing this sequence of events in humans. Thus, our objective was to determine the effect of the fermentable fibre inulin on postprandial glucose, insulin, SCFA, FFA, and gut hormone responses in healthy subjects. Overnight fasted healthy subjects (n = 12) were studied for 6 h after consuming 400 mL drinks, containing 80 g high-fructose corn syrup (80HFCS), 56 g HFCS (56HFCS), or 56 g HFCS plus 24 g inulin (Inulin), using a randomized, single-blind, crossover design. A standard lunch was served 4 h after the test drink. Glucose and insulin responses after Inulin did not differ significantly from those after 80HFCS or 56HFCS. Serum acetate, propionate, and butyrate were significantly higher after Inulin than after HFCS drinks from 4–6 h. FFAs fell at a similar rate after all 3 test drinks, but were lower after Inulin than after 56HFCS at 4 h (0.40 ± 0.06 vs. 0.51 ± 0.06 mmol·L–1; p < 0.05). Compared with 56HFCS, Inulin significantly increased plasma glucagon-like peptide-1 concentrations at 30 min, and reduced ghrelin at 4.5 h and 6 h. The results are consistent with the hypothesis that dietary fibre increases the production of colonic SCFAs, which may reduce type 2 diabetes risk by reducing postprandial FFAs and favorably affecting gut hormones, which regulate food intake.
Colonic fermentation of dietary fibre to short chain fatty acids in patients with adenomatous polyps and colonic cancer.