Optimal balance of intestinal microbiota and strengthening of ENS and vagus nerve with the presence of pro-and prebiotics alter and increase metabolites such as tryptophan and SCFAs that directly affect brain function, and the secretion level of some brain factors such as gamma-aminobutyric (GABA), serotonin/5 hydroxy tryptamine, brain-derived neurotrophic factor, and dopamine, ultimately affect mental disorders (2–5). Here, BDNF is linked to psychiatric disorder.