Lard reduces obesity in mice compared with corn oil and canola oil via modulating gut microbiota and bile acid metabolism

The association between dietary fat types and obesity is controversial, and the underlying mechanism remains unclear. This study aimed to evaluate the effect of different dietary fat sources (lard, corn oil or canola oil) on obesity in mice. The results revealed that lard-fed mice showed a lean phenotype, as well as lower serum cholesterol level compared with mice fed corn oil or canola oil. The 16S rRNA gene sequencing showed that the lard-fed mice had higher α-diversity of gut microbiota. In addition, the lard group had similar relative abundance of Lactobacillus, unclassified_f_Lachnospiraceae and Bacteroides compared with the control group. Targeted metabolomics analysis of caecal bile acid (BA) profile suggested the levels of chenodeoxycholic acid, lithocholic acid, deoxycholic acid and cholic acid in the lard group were higher than those in the corn oil and canola oil groups. Meanwhile, the levels of BA receptor farnesoid X receptor (Fxr) gene in lard-fed mice were higher than vegetable oil groups. These results suggested that lard could reduce the risk of obesity compared with corn oil and canola oil, which may be associated with more balanced gut microbiota and BA composition as well as activated FXR signaling.