To investigate the effects of different high-fat diets with various types of oils on serum lipid levels and gut microbiota in mice.

Thirty SPF male C57BL/6J mice were randomly divided into three groups based on their body weight (n = 10 per group). The normal diet group (ND) was fed a basal diet while the palm oil high-fat group (PHFD) and soybean oil high-fat group (SHFD) were fed their respective high-fat diets for 17 weeks. Blood samples were collected to evaluate serum biochemical indexes. Bacterial RNA was extracted from the feces of mice, followed by 16S rRNA sequencing.

Compared with the ND group, the body weights of mice were significantly increased in the PHFD and SHFD groups (P<0.05). Additionally, body weights of the PHFD group were significantly higher than that of the SHFD group (P<0.05). Compared with the ND group, the levels of serum total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) were significantly increased in the PHFD group (P<0.05), the levels of serum TC and triglyceride (TG) were significantly increased in the SHFD group (P<0.05), the levels of serum TC and LDL-C were significantly higher in the PHFD group compared to the SHFD group (P<0.05). The results of gut microbiota showed that compared with ND, the PCA diagrams of the β diversity presented clear distinction, the Firmicutes/Bacteroidota ratio (F/B ratio) of the PHFD group was significantly increased (P<0.05), with the PHFD group having a significantly higher F/B ratio than the SHFD group (P<0.05). Moreover, the relative abundance of Muribaculaceae was significantly decreased (P<0.05). The PHFD group had significant increases in the relative abundance of characteristic bacteria, including Ileibacterium, Pseudomonas, and Bifidobacterium (P<0.05), whereas the SHFD group had significant increases in the relative abundance of characteristic bacteria, such as Mucispirillum, Allobaculum, and Colidextribacter (P<0.05). Additionally, the function of glucose metabolism-related pathways was significantly increased in the PHFD group (P<0.05), while function of lipid metabolism-related pathway was significantly decreased in the SHFD group (P<0.05).

Different types of high-fat diets with various types of oils lead to lipid metabolism disorder and significant differences in the composition and structural changes of gut microbiota in mice. The PHFD group shows increases in the relative abundances of genuses associated with glycolipid metabolism, while the SHFD group shows increases in the relative abundances of genuses associated with lipid-metabolism and decrease in the relative abundance of antioxidant capacity.