Prevalence and association of small intestinal bacterial overgrowth with functional gastrointestinal disorders in children: A systematic review and meta-analysis

Small intestinal bacterial overgrowth (SIBO) has been implicated in the pathophysiology of functional gastrointestinal disorders (FGIDs), yet its prevalence and clinical relevance in children remain unclear. This systematic review and meta-analysis aimed to estimate the pooled prevalence of SIBO in pediatric FGIDs and assess its association with specific FGID subtypes. A comprehensive search of PubMed, Embase, Scopus, Web of Science, and Cochrane Library was conducted from inception to May 2025 for observational studies involving children (≤18 years) with FGIDs evaluated for SIBO using standardized diagnostic methods. Pooled prevalence and odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using random-effects models. Subgroup analyses were performed by FGID subtype, diagnostic modality (glucose vs. lactulose breath test), and dominant gas type (hydrogen vs. methane). Risk of bias was assessed using JBI tools; publication bias was evaluated using Begg’s and Egger’s tests. Fourteen studies comprising 2,459 children were included. The pooled prevalence of SIBO among children with FGIDs was 33.2% (95% CI: 26.8%–40.3%; I 2 = 76.5%). Compared to controls, children with FGIDs had a significantly higher likelihood of SIBO (OR = 4.06, 95% CI: 2.51–6.56). The highest prevalence was observed in irritable bowel syndrome (38.5%) and functional constipation (28.7%). Methane-dominant SIBO was notably associated with constipation-predominant FGIDs. No significant publication bias was identified. SIBO is common in pediatric FGIDs, particularly in IBS and constipation subtypes, supporting its consideration in diagnostic and therapeutic strategies for affected children.