The impact of dietary fiber supplementation on bile acid metabolism under western-diet challenge.

Dietary fibers are essential for preserving a healthy and functional gut microbiota and influence the biochemical transformation of host metabolites, such as primary bile acids. Here we show that the soluble dietary fiber oligofructose sustains the production of 6a-hydroxylated bile acids from primary bile acids by gut bacteria under western-style diet challenge. Mechanistically, we demonstrated that the effects of oligofructose on 6a-hydroxylated bile acids were microbiota dependent and specifically require functional TGR5 signaling to reduce body weight gain and improve glucose metabolism. Furthermore, we show that the 6a-hydroxylated bile acid hyodeoxycholic acid stimulates TGR5 signaling, in vitro and in vivo, and increases GLP-1R activity to improve host glucose metabolism. Modulation of the gut microbiota with dietary fibers that enrich 6a-hydroxylated bile acid levels might be a promising therapeutic strategy to alleviate obesity and type 2 diabetes.