D-allulose reduces postprandial glucose absorption in small intestine by competitive binding to glucose transport sites

Abstract

d-allulose, a C3-epimer of d-fructose, is a naturally occurring non-metabolic sugar found in small amounts. Since d-allulose can inhibit the intestinal absorption of glucose,it is necessary to investigate the role of the sodium-coupled glucose cotransporter 1 (SGLT1) in intestinal transport of d-allulose. In this study, the transcellular pathway of d-allulose in small intestinal epithelial cells was investigated by constructing a monolayer model of Caco-2 cells and in situ single-pass intestinal perfusion experiment. We observed a notable decrease in the permeation rate of d-allulose with the addition of phlorizin, a SGLT1 inhibitor, and that phloretin, a GLUT2 inhibitor, leads to a moderate decrease in the permeation rate. This suggests that both SGLT1 and GLUT2 can mediate the transport of d-allulose in small intestine. These observations were supported by computer molecular simulation. Additionally, the mRNA abundance of sugar transporters in Caco-2 cells treated with d-allulose were decreased, determined by quantitative real-time PCR. This study suggests that d-allulose can competitively bind to the sugar transport sites and reduce the mRNA abundance of sugar transporter proteins within the small intestine to effect postprandial glucose absorption.