The gut microbiota and its role in Graves' Disease: a systematic review and meta-analysis

Abstract

Emerging research indicates the potential involvement of gut bacteria in the etiology of Graves' Disease (GD). However, the evidence regarding this matter is still conflicting. The primary objective of this investigation was to examine the correlation between gut microbiota and GD. A comprehensive search was conducted of the Cochrane Library, Scopus, Europe PMC, and Medline databases up until August 1, 2023, utilizing a combination of relevant keywords. This review incorporates literature that examined the composition of gut microbiota in patients with GD. We employed random-effect models to analyze the standardized mean difference (SMD) and present the outcomes together with their corresponding 95% confidence intervals (CIs). A total of ten studies were incorporated. The results of our meta-analysis indicated that patients with GD have a reduced alpha diversity of gut microbiota as evidence by a significant reduction of Chao1 (std. mean difference -0.58; 95% CI -0.90, -0.26, p=0.0004; I² =61%), ACE (std. mean difference -0.64; 95% CI -1.09, -0.18, p=0.006; I² =77%), and Shannon index (std. mean difference -0.71; 95% CI -1.25, -0.17, p=0.01; I² =90%) when compared with healthy controls. At the phylum level, the abundance of Firmicutes was reduced in GD patients, while that of Bacteroidetes was increased. This study suggests a notable decrease in the richness and variety of gut microbiota among people diagnosed with GD in comparison with healthy controls.

Keywords: Graves’ Disease; autoimmune thyroid disease; endocrinology; gut microbiome; microbiology.

Fig. 1.

Preferred reporting items for systematic reviews and meta-analyses (PRISMA) diagram of the detailed process of selection of studies for inclusion in the systematic review and meta-analysis.

Fig. 2.

Forest plot demonstrating the alpha diversity as indicated by the Chao1 (A), ACE (B), and Shannon (C) indices in patients with Graves’ Disease (GD) when compared with healthy controls.

Fig. 3.

Forest plot demonstrating the relative abundances of the Firmicutes (A) and Bacteroidetes (B) phyla in patients with Graves’ Disease (GD) and healthy controls.