Hericium erinaceus insoluble dietary fiber alleviates obesity induced by high-fat diet through regulating the metabolic pathway influenced by gut microbiota

Hericium erinaceus (HE) is an important common edible mushroom, which is rich in dietary fiber. The objective of this study is to explore the potential lipid-reducing impact and regulation mechanism of Hericium erinaceus insoluble dietary fiber (HEIDF) by intervening mice caused by high-fat diet (HFD). The results demonstrated that HEIDF could significantly reduce hyperlipidemia induced by HFD and deposition of lipid droplets in liver and adipose cells to achieve the effect of lipid reduction. The 16S rRNA sequencing results of fecal bacteria indicated that HEIDF intervention significantly increased the abundance of Bacteroidota, norank_f_Muribaculaceae and Akkermansia, while reducing the abundance of Firmicutes and Desulfovibrio. Serum metabolomics revealed that HEIDF decreased the content of 2-isopropylmalic acid, 3-isopropylmalic acid and inosine. Relying on the correlation analysis between serum metabolites and gut microbiota, we found that with the increase of Akkermansia, norank_f_Muribaculaceae, and Acinetobacter, glycerides, bile acids, alcohols and their derivatives, fatty acids and acid conjugates of the serum were decreased. KEGG pathway enrichment showed that HEIDF could regulate the valine, leucine and isoleucine biosynthesis by improving the above gut microbiota. Therefore, this research indicated that HEIDF intervention increased the abundance of Akkermansia and norank_f_Muribaculaceae in gut microbiota, led to changes in valine, leucine and isoleucine biosynthesis, and then reduced the production of metabolites such as glycerides, bile acids, alcohols and their derivatives, which provided new insights for improving the mechanism of obesity and laid a theoretical foundation for improving the utilization rate of HEs and promoting functional foods rich in dietary fiber.