Abstract: The hypolipidemic effect and mechanism of konjac glucomannan (KGM) were investigated in hyperlipidemic hamsters from the perspective of the relationship between the gut microbiota and bile acid metabolism. Five-week-old hamsters were divided randomly into control, high fat diet (HFD), 2% (m/m) KGM, 6% KGM and 10% KGM groups. Serum and hepatic lipid levels were assessed, and the effect of KGM treatment on the gut microbiota and bile acid metabolism were analyzed after five-week administration. Our results suggested that 6% and 10% KGM treatments significantly decreased serum total cholesterol (TC), triglyceride (TG), low density lipoprotein cholesterol (LDL-C) and hepatic TC levels. Totally 51 differential metabolites were found between the HFD versus control and KGM groups, and enrichment analysis showed that bile acids accounted for the highest proportion (24%) of the total number of metabolites. Moreover, Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis showed a significant alteration in the primary bile acid synthesis pathway. Administration with 6% and 10% KGM significantly reduced the relative abundance of Bilophila and bile salt hydrolase (BSH)-related bacteria, Bifidobacterium and Lactobacillus, and decreased the levels of deoxycholic acid (DCA) and lithocholic acid (LCA) in cecal contents. Besides, the mRNA expression of cholesterol 7α-hydroxylase (CYP7A1) was unregulated in the 6% KGM group. Taken together, KGM treatment significantly decreased the relative abundance of Bilophila and BSH-related bacteria in the gut, upregulated the gene expression of CYP7A1 to regulate the levels of bile acids, thus modulating dyslipidemia.

Key words: konjac glucomannan; hypolipidemic effect; gut microbiota; bile acids