Kim et al. reported that the excessive intake of an HFD could cause disturbance of gut microbiota composition, especially an increase in the Proteobacteria population, which in turn resulted in increasing plasma concentration of lipopolysaccharide (LPS), inhibiting hippocampal brain-derived neurotrophic factor (BDNF) expression, and consequently inducing the phenotypes of psychiatric disorders in mice [159]. This evidence concerns the gene BDNF and psychiatric disorder.