Role of Gut Microbiota in the Aetiology of Obesity: Proposed Mechanisms and Review of the Literature

Table 4

Association of gut microbial species/genera with obesity or leanness in human studies.

Bacteria	Association with obesity	Group	Level	Other associations	Reference
Lactobacillus reuteri	+ve	Firmicutes	Species	—	[44, 45]
Clostridium cluster XIVa	+ve	Firmicutes	Group	Anti-inflammatory	[46]
E. coli	+ve	Proteobacteria	Species	Nonalcoholic steatohepatitis (NASH)	[46]
Staphylococcus spp.	+ve	Firmicutes	Genus	Energy intake	[47]
Bacteroides	−ve/+ve	Bacteroidetes	Genus	Controversial	[5]
Akkermansia muciniphila	−ve	Verrucomicrobia	Species	Mucus degradation	[42]
Methanobrevibacter smithii	−ve	Archaea	Species	Increase in anorexia	[48]
Clostridium cluster IV; F. prausnitzii	−ve	Firmicutes	Species	Anti-inflammatory	[49]
Bifidobacteria	−ve	Actinobacteria	Genus	−ve association with allergy	[44]

Associations based on correlation or regression analysis or statistically significant differences between the lean and obese. +ve: positive association, −ve: negative association, and +ve/−ve: controversial.