Alterations in short-chain fatty acids and serotonin in irritable bowel syndrome: a systematic review and meta-analysis

Mei Luo,Zhenyi Tian,Lishou Xiong,Xiaojun Zhuang

doi:10.1186/s12876-020-01577-5

Abstract

BackgroundShort-chain fatty acids (SCFAs) and serotonin (5-hydroxytryptamine, 5-HT) may be associated with the pathogenesis of irritable bowel syndrome (IBS). There are some reports of alterations in SCFAs and 5-HT in IBS, but their results are inconsistent. We aimed to perform a meta-analysis to assess alterations in SCFAs and 5-HT in IBS patients and their potential role in the abnormal brain-gut-microbiota (BGM) axis.MethodsCase–control studies detecting SCFAs and 5-HT in IBS patients were identified from PubMed, Web of Science, Cochrane Library, and Scopus databases to identify relevant articles up to September 2018. The standardized mean differences (SMDs) with 95% confidence intervals (CIs) of SCFAs and 5-HT were calculated by REVIEW MANAGER 5.3 to evaluate the alterations of 5-HT and SCFAs in IBS.ResultsFive studies on SCFAs and 5 on 5-HT in IBS patients were included. As compared to healthy controls (HCs), the SMDs of 5-HT in IBS patients was 2.35 (95% CI 0.46–4.24) and the SMDs of total SCFAs, acetic acid, propionic acid, and butyric acid in IBS patients were − 0.01 (95% CI − 0.57–0.55), − 0.04 (95% CI − 0.55–0.47), 0.07 (95% CI − 0.45–0.60), and − 0.00 (95% CI − 0.49–0.49), respectively.ConclusionsThere was an increase in 5-HT in blood of IBS patients, indicating the increased 5-HT in blood may be involved in IBS pathogenesis. However, there were no significant differences in SCFAs in feces between IBS patients and HCs. But the study did not differentiate between subgroups of IBS. These findings might provide insight for future studies of the BGM axis in the pathogenesis of IBS.Mei Luo and Xiaojun Zhuang contributed equally to the writing of this article

Highlights

Short-chain fatty acids (SCFAs) and serotonin (5-hydroxytryptamine, 5-HT) may be associated with the pathogenesis of irritable bowel syndrome (IBS)
There were no significant alterations in shortchain fatty acids (SCFAs) in IBS patients, some studies have reported that SCFAs are altered in the feces of IBS patients [25, 27, 28]
Some studies have reported alterations in SCFAs in feces of IBS patients and the association of these alterations with symptoms in IBS patients, we found no significant differences in SCFA levels in feces in IBS patients and healthy controls (HCs) in our meta-analysis

Summary

Introduction

Short-chain fatty acids (SCFAs) and serotonin (5-hydroxytryptamine, 5-HT) may be associated with the pathogenesis of irritable bowel syndrome (IBS). We aimed to perform a meta-analysis to assess alterations in SCFAs and 5-HT in IBS patients and their potential role in the abnormal brain-gut-microbiota (BGM) axis. Visceral hypersensitivity, altered gastrointestinal permeability, immune dysfunction or psychological disorder have been generally accepted as potential contributors to the pathogenesis of IBS [3]. Accumulating evidence has demonstrated that alterations in gut microbiota and dysregulation of the brain-gut axis may be associated with IBS pathogenesis [4,5,6,7]. The gut microbiota may be involved in IBS pathogenesis through the production of metabolites such as shortchain fatty acids (SCFAs) [8]. In the brain-gut axis, the neurotransmitter serotonin (5-hydroxytryptamine, 5-HT), associated with visceral hypersensitivity and. Mounting evidence detailing the bidirectional interactions between the gut microbiota and the brain supports the concept of the brain-gut-microbiota (BGM) axis, integrating the central nervous system (CNS), gastrointestinal tract (GIT), and microbiota [11, 12]

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