Influence of the intestinal microbiota in the genesis of obesity: an integrative literature review

Abstract

Introduction: The intestinal microbiota plays a fundamental role in the human immune response and changes in the proportions of the Firmicutes and Bacteroidetes phyla and dietary patterns (diets) may be associated with obesity.

Objective: To describe the relationship of the Firmicutes and Bacteroidetes phyla with obesity.

Materials and Methods: Survey of pre-clinical and clinical experimental studies, from 2005 to 2020, in the databases: Pubmed and Google academic, using the following search terms: Obesity, Firmicutes, Bacteroidetes and intestinal microbiome, exploring the relationship between obesity and microorganisms, evaluating the following questions: “Are Firmicutes and Bacteroidetes indicators/risk factors for obesity?”; “Does the diet influence the diversity of the intestinal microbiota and body weight?”.

Results: Ten articles were analyzed (5 pre-clinical and 5 clinical experimental studies), which showed a correlation between the intestinal microbiota and obesity.

Discussion: Pre-clinical experimental studies demonstrate increased proportions of Firmicutes compared to Bacteroidetes in the intestinal microbiota of obese mice (some cases with selected genetics). However, in experimental clinical studies, this evidence is deconstructed by other authors, who still do not clearly establish, which proportions of the Firmicutes and Bacteroidetes phyla are associated with obesity.

Conclusion: Only in preclinical models the proportions of Firmicutes/Bacteroidetes are associated with obesity.