d-Allulose is a substrate of glucose transporter type 5 (GLUT5) in the small intestine.

D-Allulose has been reported to have beneficial health effects. However, the transport system(s) mediating intestinal D-allulose transport has not yet been clearly identified. The aim of this study was to investigate whether intestinal D-allulose transport is mediated by glucose transporter type 5 (GLUT5). When D-allulose alone was gavaged, plasma D-allulose levels were dramatically higher in rats previously fed fructose. This suggests enhanced intestinal D-allulose absorption paralleled increases in GLUT5 expression observed only in fructose-fed rats. When D-allulose was gavaged with D-fructose, previously observed increases in plasma D-allulose levels were dampened and delayed, indicating D-fructose inhibited transepithelial D-allulose transport into plasma. Tracer D[C-14]-fructose uptake rate was reduced to 54.8% in 50mM D-allulose and to 16.4% in 50mM D-fructose, suggesting D-allulose competed with D-[C-14]-fructose and the affinity of D-allulose for GLUT5 was lower than that of D-fructose. GLUT5 clearly mediates, likely at lower affinity relative to D-fructose, intestinal D-allulose transport.