Short chain fatty acid absorption in lean vs obese humans

Abstract

Short chain fatty acids (SCFA) produced during the colonic fermentation of dietary fiber may reduce risk for obesity and type 2 diabetes. Our objectives were to determine if fecal SCFA concentration and absorption differ and/or are correlated in lean and overweight/obese (OW) subjects. Lean (n=11) and OW (n=11) subjects were recruited. After completing a 3‐day diet record subjects provided a fresh fecal sample to measure SCFA concentration. Subjects then inserted a rectal dialysis bag filled with 10ml of SCFA solution for 30 min. The procedures were repeated after two weeks. Fecal SCFA was higher in OW than lean subjects (80±6 vs 56±6 mmol/kg, p=0.02). The rate of SCFA absorption was similar and proportional to the SCFA concentration in the dialysis bag in both groups. There was a significant positive correlation between the SCFA absorption and fecal SCFAs for the OW group (r 0.44, p=0.04), but not for the lean group (r −0.22, p= 0.33) (difference in slopes, p=0.03). Since SCFA absorption from the dialysis bag was concentration dependent in the groups, OW people may absorb more colonic SCFA from their own feces. Within the OW group, the positive correlation between SCFA absorption and fecal SCFA concentration may be a result of upregulation of transporter expression for ionic diffusion.This work was supported by a grant from the Canadian Institutes for Health Research.