Glucomannan promotes Bacteroides ovatus to improve intestinal barrier function and ameliorate insulin resistance

Bioactive dietary fiber has been proven to confer numerous health benefits against metabolic diseases based on the modification of gut microbiota. The metabolic protective effects of glucomannan have been previously reported in animal experiments and clinical trials. However, critical microbial signaling metabolites and the host targets associated with the metabolic benefits of glucomannan remain elusive. The results of this study revealed that glucomannan supplementation alleviated high-fat diet (HFD)-induced insulin resistance in mice and that its beneficial effects were dependent on the gut microbiota. Administration of glucomannan to mice promoted the growth of Bacteroides ovatus. Moreover, colonization with B. ovatus in HFD-fed mice resulted in a decrease in insulin resistance, accompanied by improved intestinal barrier integrity and reduced systemic inflammation. Furthermore, B. ovatus-derived indoleacetic acid (IAA) was established as a key bioactive metabolite that fortifies intestinal barrier function via activation of intestinal aryl hydrocarbon receptor (AhR), leading to an amelioration in insulin resistance. Thus, we conclude that glucomannan acts through the B. ovatus-IAA-intestinal AhR axis to relieve insulin resistance.