Research on the mechanism by which a high-fiber diet regulates the gut microbiota-bile acid metabolism axis and improves glucose metabolism

Abstract

This study examined how a high-fiber diet affects the gut–bile-acid pathway and blood sugar control in mice with type 2 diabetes. Thirty-six male C57BL/6J mice were assigned to three groups: normal control, diabetic control, and high-fiber diet. After 12 weeks, bile acids, gene markers, and gut bacterial changes were tested. LC–MS/MS showed that total secondary bile acids increased by 62%, intestinal FXR expression dropped by 35%, and plasma FGF19 rose about two times compared with diabetic controls. Gut RNA data showed higher activity of bile-acid–related genes and more Faecalibacterium, which was strongly linked with dehydroxylation levels (r = 0.78, P < 0.01). These results show that a high-fiber diet changes bile-acid balance through gut bacteria and adjusts the FXR–FGF19 signal to support better glucose control. The findings suggest that adding dietary fiber may be a simple and safe way to improve metabolism in diabetes.