Table 1.

The role of diet in microbiota regulation.

Type of Diet	Impact on Microbiota	References
Western diet	Decreased levels of intestinal microbiotic diversity (reduced number of members of the phylum Bacteroidetes has been found, along with higher levels of Proteobacteria and Firmicutes).	Tengeler et al., 2018 [3]
	Increase in fatty acids levels leads to pro-inflammatory state, through the already-mentioned effect of altered microbiota on intestinal wall permeability (increased susceptibility to psychiatric and neurological diseases).	Evrensel et al., 2015 [174]
Mediterranean diet	Increased diversity of microbiome composition, with a decreased concentration of Firmicutes, Proteobacteria and Clostridia, and an increase in Bifidobacteria and Lactobacillus.	Singh et al., 2017 [39]
	Reduced inflammation levels, decreased cytokines release and a greater modulation on intestinal permeability.	Tanaka et al., [175]
Vegetarian and vegan diet	Decreased representation of Enterobacteriaceae and increase of Bacteroides and Prevotella	do Rosario et al., 2016 [176]
	Reduction in Bacteroides Fragilis and Clostridium with subsequent decrease of risk factors for chronic inflammation	Ferrocino et al., 2015 [177]