Barley beta-glucan consumption improves glucose tolerance by increasing intestinal succinate concentrations
Barley is rich in beta-glucan, which can alter gut microbiota and metabolome profiles, potentially affecting host metabolism. However, the microbiota and metabolites increased by barley beta-glucan remain unclear. In this study, we focused on the gut-microbiota-derived metabolite succinate and investigated the microbiome and metabolome profiles altered by barley beta-glucan intake. C57BL/6J mice were fed a standard or middle-fat diet containing barley flour rich in beta-glucan or barley flour without beta-glucan, and their gut microbiota and metabolome profiles were analyzed. The results showed increased Bacteroides, Parasutterella, and succinate due to barley beta-glucan intake independent of diet differences. Next, we used mice lacking slc13a2, a gene that is involved in the cellular uptake of succinate. Wild-type mice showed improved glucose tolerance after the intake of barley beta-glucan, but this effect was attenuated in the slc13a2-deficient mice. These results suggest that barley beta-glucan intake increases succinate and succinate-producing bacteria and affects glucose metabolism.