The KEGG pathway analysis using PICRUSt 2.0 showed that after HF diet introduction, the pathways involved in the biosynthesis of various secondary metabolites-pathway, choline metabolism in cancer, nitrotoluene degradation, endocytosis, furfural degradation, prodigiosin biosynthesis and pyruvate metabolism were significantly increased, but the CAMP signaling pathway, cholesterol metabolism, legionellosis and shigellosis were significantly decreased relative to the HS group (Figure 5A). The gene discussed is CAMP; the disease is legionellosis.