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

Abstract 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

Hypoglycemic mechanism of polysaccharide from Cyclocarya paliurus leaves in type 2 diabetic rats by gut microbiota and host metabolism alteration

Diabetes mellitus is a serious threat to human health.Cyclocarya paliurus(Batal.) Iljinskaja (C.paliurus) is one of the traditional herbal medicine and food in China for treating type 2 diabetes, and theC. paliuruspolysaccharides (CP) were found to be one of its major functional constituents. This research aimed at investigating the hypoglycemic mechanism for CP. It was found that CP markedly attenuated the symptoms of diabetes, and inhibited the protein expression ofBax, improved the expression ofBcl-2in pancreas of diabetic rats, normalized hormones secretion and controlled the inflammation which contributed to the regeneration of pancreatic beta-cell and insulin resistance. CP treatment increased the beneficial bacteria genusRuminococcaceaeUCG-005 which was reported to be a key genus for protecting against diabetes, and the fecal short-chain fatty acids levels were elevated. Uric metabolites analysis showed that CP treatment helped to protect with the diabetes by seven significantly improved pathways closely with the nutrition metabolism (amino acids and purine) and energy metabolism (TCA cycle), which could help to build up the intestinal epithelial cell defense for the inflammation associated with the diabetes. Our study highlights the specific mechanism of prebiotics to attenuate diabetes through multi-path of gut microbiota and host metabolism

In vitro assessment of the effect of four polysaccharides on intestinal bacteria of mice with colitis

Abstract Polysaccharides are typically resistant to digestion in the gastrointestinal tract and are instead degraded by gut microbiota in the colon. As such, they are commonly employed as carriers for colon‐targeted drugs, with the potential to regulate gut microbiota. Pectin, carrageenan, guar gum, and xanthan gum are commonly used polysaccharide carriers, but their degradation in the gut microbiota under colitis conditions as well as their effects on gut microbiota remains unclear. In this study, we performed the in vitro fermentation of these four polysaccharides using colonic content microbiota from mice with colitis and evaluated the degree of polysaccharide degradation and the effects on pH, short‐chain fatty acids, and gut microbiota. Our findings indicate that pectin and guar gum had a greater degree of degradation and promoted the production of butyrate, inhibited the proliferation of harmful bacteria (e.g., Enterobacteriaceae), and increased beneficial bacteria (e.g., Bifidobacterium). In contrast, carrageenan and xanthan gum promote the proliferation of Enterobacteriaceae. These results provide theoretical guidance for the selection of drug delivery carriers for inflammatory bowel disease treatment and provide information on the relationship between polysaccharides and gut microbiota

Parabacteroides distasonis ameliorates insulin resistance via activation of intestinal GPR109a

Abstract Gut microbiota plays a key role in insulin resistance (IR). Here we perform a case-control study of Chinese adults (ChiCTR2200065715) and identify that Parabacteroides distasonis is inversely correlated with IR. Treatment with P. distasonis improves IR, strengthens intestinal integrity, and reduces systemic inflammation in mice. We further demonstrate that P. distasonis-derived nicotinic acid (NA) is a vital bioactive molecule that fortifies intestinal barrier function via activating intestinal G-protein-coupled receptor 109a (GPR109a), leading to ameliorating IR. We also conduct a bioactive dietary fiber screening to induce P. distasonis growth. Dendrobium officinale polysaccharide (DOP) shows favorable growth-promoting effects on P. distasonis and protects against IR in mice simultaneously. Finally, the reduced P. distasonis and NA levels were also validated in another human type 2 diabetes mellitus cohort. These findings reveal the unique mechanisms of P. distasonis on IR and provide viable strategies for the treatment and prevention of IR by bioactive dietary fiber