Systematic comparison of seven animal protein sources reveals more favorable glucose homeostasis in mice fed duck protein compared with pork protein, associated with gut microbiota and secondary bile acid metabolism.

Animal protein sources may differentially influence glucose homeostasis, yet the underlying mechanisms remain unclear. We investigated how casein, pork, beef, mutton, chicken, duck, and goose proteins differentially affected glucose homeostasis in mice and their associations with gut microbiota and bile acids. Mice fed duck protein exhibited more favorable glucose tolerance and insulin sensitivity than those fed pork protein. These differences were accompanied by coordinated alterations in gut microbiota and bile acid profiles, including enrichment of Clostridium, increased abundance of the baiE gene, and elevated secondary bile acids. Compared with pork protein, duck protein intake increased ileal fibroblast growth factor 15 expression and portal active glucagon-like peptide-1 concentrations, upregulated adipose thermogenic and lipid oxidation genes, while downregulating hepatic gluconeogenic genes. Correlation analysis revealed associations between these genes and glucose metabolic parameters. Collectively, alterations in the microbiota-bile acid axis may contribute to the favorable glucose homeostasis observed in duck protein-fed mice.