Crystalline cellulose reduces plasma glucose concentrations and stimulates water absorption by increasing the digesta viscosity in rats.

Although cellulose is generally considered not to affect the viscosity of the digesta in the upper gastrointestinal tract, we found previously that the ingestion of cellulose elevated the viscosity of the gastric, small intestinal, and cecal contents when particulate matter was included in the measurements. We hypothesized that the digesta viscosity influences absorption. Here, we examined the effects of crystalline cellulose on plasma glucose concentrations by infusing control and cellobiose- and cellulose-containing artificial digesta of approximately 30 mL into the small intestine of rats. Cellulose, but not cellobiose, decreased the postinfusion plasma glucose concentration (P < 0.05), although cellulose did not cause adsorption or dilution of glucose. Among the physical properties of the artificial digesta, only viscosity was responsible for the decrease in the plasma glucose concentration, whereas water content, free water, bound water, and osmotic pressure were not. The cellulose-induced increase in digesta viscosity may delay glucose diffusion in the lumen, as found in our previous study. Cellulose also stimulated water absorption from the small intestine (P < 0.05), which may be attributable to increases in the water potential of the digesta moving through the small intestine. The ingestion of cellulose with meals, which increases digesta viscosity, is likely to modulate the postprandial plasma glucose concentration and to reduce the incidence of diarrhea associated with enteral nutrition.