# IBS and SIBO: Gut Microbiota, Pathophysiology, and Non-Pharmacological Interventions

## TL;DR

This paper reviews how gut bacteria and non-drug treatments affect IBS and SIBO, focusing on managing symptoms without antibiotics.

## Contribution

The paper provides an integrative framework for non-pharmacological interventions in IBS and SIBO, emphasizing microbiota interactions and reducing antibiotic use.

## Key findings

- Gut microbiota and their metabolites significantly influence IBS and SIBO symptoms like motility and inflammation.
- Non-antibiotic strategies such as diet, probiotics, and mind-body therapies show promise in managing IBS/SIBO symptoms.
- Methanogen overgrowth is linked to constipation-predominant IBS, while hydrogen and hydrogen sulfide are associated with diarrhea and bloating.

## Abstract

Irritable bowel syndrome (IBS) and small intestinal bacterial overgrowth (SIBO) share symptoms such as abdominal pain, bloating, and altered bowel habits. Both are linked to dysbiosis and gut–brain axis dysfunction. IBS is a multifactorial disorder characterized by abnormal motility, visceral hypersensitivity, low-grade inflammation, and alterations in the microbiota. In contrast, SIBO is defined by excessive bacterial colonization of the small intestine that can mimic or worsen IBS symptoms. Gut microbes and their metabolites influence motility, immune activation, barrier integrity, and gas production; methanogen overgrowth is associated with constipation-predominant presentations, while hydrogen- and hydrogen sulfide-related pathways may contribute to diarrhea and bloating. Because recurrent or empiric antibiotic use is common—particularly in suspected SIBO—yet carries risks of resistance, microbiome disruption, and relapse, there is a strong rationale to prioritize effective non-antibiotic strategies. Accordingly, this review synthesizes current evidence on IBS/SIBO pathophysiology and microbiota interactions. It evaluates non-pharmacological interventions including dietary approaches, probiotics/prebiotics, herbal therapies, and mind–body treatments (e.g., cognitive behavioral therapy and gut-directed hypnotherapy). We emphasize an integrative framework that supports symptom control and quality of life while helping reduce unnecessary antibiotic exposure.