Acute increases in serum colonic short-chain fatty acids elicited by inulin do not increase GLP-1 or PYY responses but may reduce ghrelin in lean and overweight humans.

Abstract

BackgroundColonic fermentation of dietary-fibre to short-chain-fatty-acids (SCFA) influences appetite hormone secretion in animals, but SCFA production is excessive in obese animals. This suggests there may be resistance to the effect of SCFA on appetite-hormones in obesity.Objectivesto determine the effects of inulin (IN) and resistant-starch (RS) on postprandial SCFA, and gut hormone (GLP-1, PYY, and ghrelin) responses in healthy overweight/obese (OWO) vs lean (LN) humans.MethodsOvernight fasted participants (13 OWO, 12 LN) consumed 300mL water containing 75g glucose (GLU) as Control, or 75g glucose plus 24g IN, or 28.2g RS using a randomized, single-blind, cross-over design. Blood for appetite-hormones and SCFA was collected at intervals over 6h. A standard lunch was served 4h after the test drink.ResultsRelative to GLU, IN, but not RS, significantly increased SCFA AUC from 4–6h (AUC4-6). Neither IN nor RS affected GLP-1 or PYY-AUC4-6. Although neither IN nor RS reduced ghrelin-AUC4-6 compared to GLU, ghrelin at 6h after IN was significantly lower than that after GLU (p<0.05). After IN, relative to GLU, the changes in SCFA-AUC4-6 were negatively related to the changes in ghrelin-AUC4-6 (p=0.017). SCFA and hormone responses did not differ significantly between LN and OWO.ConclusionsAcute increases in colonic SCFA do not affect GLP-1 or PYY responses in LN or OWO subjects, but may reduce ghrelin. The results do not support the hypothesis that SCFA acutely stimulate PYY and GLP-1 secretion; however, a longer adaptation to increased colonic fermentation or a larger sample size may yield different results.