Oat β-Glucan and Lacticaseibacillus paracasei K56 synergistically ameliorate hypercholesterolemia in mice by modulating gut microbiota and bile acid metabolism

CFU/kg), OBG (1 g/kg/day) or their combination. The combination treatment demonstrated superior efficacy, reducing total cholesterol (TC) by 41.19 ± 7.13 % (vs model group) and low-density lipoprotein cholesterol (LDL-C) by 37.47 ± 6.55 % (vs model group), with 24.37 ± 9.18 % (vs OBG group) and 15.10 ± 10.30 % (vs K56 group) greater TC reduction. Liver histopathology showed 3.7-fold reduction in steatosis scores versus model group. Mechanistically, compared with the model group, the combination upregulated hepatic CYP7A1/CYP27A1 expression by 5.75 ± 0.51-fold and 2.34 ± 0.21-fold respectively, increased fecal bile acids and enriched bile acid producing bacteria. In summary, L. paracasei K56 and OBG synergistically regulate gut microbiota and bile acid metabolism, promoting the conversion of cholesterol into bile acids, thereby alleviating hypercholesterolemia in mice.