Research Paper Volume 16, Issue 8 pp 7448—7459

Exploring causality in the association between gut microbiota and irritable bowel syndrome risk: a large Mendelian randomization study

Jishi Zhang1, , Xinlin Shi1, , Yun Wang2, ,

  • 1 Department of General Surgery, Huangdao District People’s Hospital, Qingdao, Shandong, China
  • 2 Department of Hepatology/Infectious Diseases, Huangdao District People’s Hospital, Qingdao, Shandong, China

Received: June 19, 2023       Accepted: March 18, 2024       Published: April 25, 2024
How to Cite

Copyright: © 2024 Zhang et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.


Background: In the past, some observational studies have highlighted the correlation between gut microbiota and irritable bowel syndrome (IBS). However, it is still unknown if the composition of gut microbiota shows a causal effect on the risk of IBS.

Aim: To conduct Mendelian randomization (MR) analysis of the samples to study the probable causal relationship between the gut microbiota, their taxonomic groups, and the risk of IBS.

Materials and Methods: In this study, the summarized data regarding 211 gut microbiota and their IBS genome-wide association studies (GWAS) were collected from public databases. The causal estimates were determined using five MR techniques, where Inverse Variance Weighted (IVW) regression was employed as the major MR technique. Herein, MR-PRESSO and MR-Egger intercept tests were conducted to prevent horizontal pleiotropy. Cochran’s Q test was used to evaluate heterogeneity using the IVW and MR-Egger techniques.

Results: IVW results showed that gut microbes, belonging to Class Gammaproteobacteria (P = 0.04; OR = 1.45), Family XIII (P = 0.03; OR = 1.34), Family Prevotellaceae (P = 0.003; OR =1.24), and Lachnospiraceae UCG004 (P = 0.049; OR = 1.19) increased the risk of IBS, while Alcaligenaceae (P = 0.03; OR = 0.83, 95% CI: 0.69–0.98) and Coprobacter (P = 0.02; OR = 0.86, 95% CI: 0.76–0.98) decreased the risk of IBS.

Conclusions: This study presented novel insights that highlighted the causal relationship between gut microbiota and IBS, and offered new treatment strategies for preventing or treating IBS.


IBS: irritable bowel syndrome; MR: Mendelian randomization; GWAS: genome-wide association studies; IVW: Inverse Variance Weighted.