Oat β-glucan reshapes gut microbiota to enhance glucose homeostasis via coordinated modulation of bile acid conjugation and succinate-dependent intestinal gluconeogenesis

Dietary fibers-induced gut microbiota changes influence diabetes through bile acid metabolism. Oat β-glucan is a beneficial dietary fiber that improves glucose metabolism, but its mechanism of regulating gut microbiota-mediated bile acid metabolism and exerting hypoglycemic effects remains unclear. Here, we found that oat β-glucan improved glucose intolerance and insulin resistance and promoted glucagon-like peptide-1 (GLP-1) secretion in obese mice. The enhanced production of secondary bile acids such as lithocholic acid (LCA) and deoxycholic acid (DCA), which were associated with the enriched Faecalibaculum , norank_f_Muribaculaceae , Bifidobacterium and Akkermansia induced by oat β-glucan, were proven to promote GLP-1 secretion via inhibiting FXR. Simultaneously, succinic acid, which was elevated in fecal metabolites by oat β-glucan, was linked to enhanced intestinal gluconeogenesis and contributed to GLP-1 secretion. Overall, oat β-glucan modulated gut microbiota to increase secondary bile acids and succinic acid, thereby stimulating GLP-1 secretion to promote glucose metabolism in mice fed a Western diet.