Effects of in vitro simulated digestion on the hypoglycaemic capacity of wheat bran-soluble dietary fibre

Wheat bran-soluble dietary fibre (WB-SDF) is known for its hypoglycaemic properties and its potential to control postprandial blood glucose levels in individuals with hyperglycaemia. However, the digestive process may alter its glucose-lowering potential. This study investigated the effects of in vitro simulated digestion on the hypoglycaemic efficacy of WB-SDF. The hypoglycaemic effects of WB-SDF were determined by examining its glucose-binding capacity, glucose dialysis retardation index and ability to inhibit glucose uptake and transport in Caco-2 cells. Structural changes after digestion were analysed via polysaccharide conformation analysis, microstructure observation and particle size measurements to evaluate their impacts on hypoglycaemic efficacy. Results indicate that WB-SDF and digested wheat bran-dietary fibre significantly decreased glucose adsorption and α-glucosidase activity compared with the control group in Caco-2 cells. However, simulated digestion resulted in a relatively smaller reduction in α-glucosidase activity compared with the WB-SDF treatment group. The massive loss of surface laminar structure, reduction of –OH groups and partial glycosidic bond breakage in digested wheat bran-dietary fibre after digestion led to reduced glucose adsorption capacity and glucose dialysis retardation index. Moreover, the reduction in particle size after digestion enhanced the inhibition of glucose transport–related gene expression in Caco-2 cells. Thus, although digestion weakens the glucose adsorption of WB-SDF, it improves its ability to inhibit glucose transport, highlighting the intricate interplay between structural modifications and hypoglycaemic efficacy.