Dietary Interventions With <i>Schleiferilactobacillus harbinensis</i> Z171, Its EPS and Postbiotics Ameliorate Cholesterol Metabolism via Modulating the Gut‐Liver Axis in High‐Fat Diet‐Fed Mice

Dietary interventions represent safe and healthy strategies for reducing cholesterol levels and improving metabolic health. This study aimed to investigate the effects of the probiotic Schleiferilactobacillus harbinensis Z171, its extracellular polysaccharides (EPS), and postbiotics on cholesterol metabolism in the gut of mice fed a high-fat diet. The analysis focused on total cholesterol and bile acid levels in intestinal contents and serum, as well as bile acid reabsorption, short-chain fatty acid (SCFA) levels, gut microbiota composition, and metabolomic profiles. The results showed that high-dose EPS (400 mg/kg body weight), live S. harbinensis Z171, and postbiotics significantly increased fecal bile acid excretion to 86.49, 79.94, and 85.20 µmol/L, and SCFA production to 33.12, 28.71, and 29.01 µmol/g, respectively. Conversely, they decreased fecal cholesterol levels to 7.96, 8.26, and 5.93 µmol/L, respectively. Fecal metabolomics revealed an enrichment of metabolites related to bile acid biosynthesis. Gut microbiota analysis showed an increase in beneficial bacterial species associated with SCFA production, which improved lipid metabolism and gut health. Specifically, high-dose EPS enriched Faecalibaculum and Enterorhabdus in the gut, S. harbinensis Z171 increased Bifidobacterium abundance, and postbiotics elevated Dubosiella and Akkermansia levels. These findings suggest these interventions are promising strategies for regulating cholesterol metabolism through gut-liver axis mechanisms.