Fiber supplementation in irritable bowel syndrome: a systematic review and meta-analysis of randomized controlled trials
In brief
Fiber boosts IBS clinical response by 8% overall, psyllium by 50%
In a meta-analysis of 30 trials with 1,904 IBS patients, 52% responded to fiber versus 44% to placebo, a modest absolute gain of eight percent; the benefit was driven by psyllium, which increased response rates by about half. Overall gastrointestinal symptom scores did not improve, and data on IBS subtypes remain sparse.
- Journal
- Gastroenterology (Q1)
- Published
- 14 August 2026
- Study design
- Systematic review / meta-analysis of RCTs
- Evidence level
- Level 1, High (CEBM 1a)
- Authors
- Heidi M Staudacher, Valeria Rucco, Sara Mancell, Eirini Dimidi, Kevin Whelan
- PMID
- 42600900
- DOI
- 10.1053/j.gastro.2026.07.027
Why clinicians should know about it
- Picked for Complementary and Alternative Medicine (top studies of the week, 16 August 2026): Systematic review of fiber supplements for IBS
- Picked for Gastroenterology (top studies of the week, 16 August 2026): Fiber supplementation, especially psyllium, improves IBS symptoms
Abstract
BACKGROUND AND AIMS: Fiber supplementation is widely used and recommended for irritable bowel syndrome (IBS), however there is no recent evidence synthesis. We aimed to investigate the efficacy of fiber supplements in IBS through a systematic review and meta-analysis of randomized controlled trials. METHODS: We searched MEDLINE, Embase, Web of Science, and Cochrane Central Register of Controlled Trials (inception to 9 April 2026). Trials recruiting adults with IBS that investigated fiber supplements compared with a suitable placebo control were included. Dichotomous clinical response data were summarized with a risk ratio and 95% confidence intervals. The review was registered prospectively on PROSPERO (CRD42024600758). RESULTS: The search identified 4008 records, and 30 RCTs were eligible including 1904 people with IBS. The most common fiber types were wheat bran (n=7), psyllium (n=6), inulin-type fructans (n=5), and β-galacto-oligosaccharides (B-GOS) (n=2) and two RCTs used fiber co-administration. Sixteen RCTs (n=1293) reported clinical response, with 52% responding to fiber vs 44% to control (RR 1.21 [CI 1.03 to 1.41]; P=0.02; I2=38%), with benefit specifically for psyllium (RR 1.53 [95% CI 1.06 to 2.19]). Nine RCTs (n=497) reported overall GI symptoms (integrative scores), showing no significant effect (SMD -0.25 [95% CI -0.67 to 0.17]; P=0.25; I2 =78%), except for B-GOS, which improved symptoms. Subgroup analysis for IBS subtype was not possible for most outcomes. CONCLUSIONS: Fiber supplementation, and specifically psyllium, leads to clinical response in IBS. Future RCTs should report outcomes for individual IBS subtypes or only recruit specific IBS-subtypes to better enable identification of distinct patterns of response.
Abstract as published, via PubMed.
For healthcare professionals. The summary is generated by AI from the published abstract, and the evidence level is assigned automatically from the study design on the Oxford CEBM hierarchy. Neither is medical advice. Read the full paper before changing practice.