Modeling of fluid flow, carbohydrate digestion, and glucose absorption in human small intestine

The aim of this study was to develop a numerical model for simulating fluid flow, carbohydrate digestion, and glucose absorption in human small intestine. COMSOL Multiphysics® software was used to develop the numerical model. The intestinal geometry parameters, motility parameters, intestinal content properties, and digestion kinetics were obtained from the literature. The glucose absorption process was simulated by assuming that the intestinal tube is enclosed in an outer cylindrical tube with an intermediate diffusion wall. The properties of the intermediate diffusion wall were estimated by comparing numerical predictions with experimental results of in vitro digestion of 5 g glucose and 5 g maltodextrin in water-based food solutions. The jejunum numerical model with the intermediate diffusion wall of 2 mm thickness and the glucose diffusivity value of 5.25 × 10⁻⁹ m²/s, predicted the experimental cumulative jejunal glucose absorption values of 3.67 g (glucose feed) and 3.74 g (maltodextrin feed) with an average error of 0.07 g and 0.2 g, respectively.