Characteristics and clinical applicability of four dietary interventions for irritable bowel syndrome: A systematic review and meta-analysis.

BACKGROUND: Dietary interventions are first-line management for irritable bowel syndrome (IBS), but their relative efficacy, acceptability, and safety remain incompletely understood. This systematic review and meta-analysis aimed to comprehensively evaluate four dietary interventions for adult patients with IBS: the low FODMAP diet (LFD), Mediterranean-based dietary interventions (including the Mediterranean diet [MD] and Mediterranean low-FODMAP diet [MED-LFD]), traditional dietary advice (TDA), and emerging dietary interventions (including the starch- and sucrose-reduced diet [SSRD] and gluten-free diet [GFD]).

METHODS: We searched PubMed, Embase, Web of Science, the Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov, and the World Health Organization International Clinical Trials Registry Platform (WHO ICTRP) for randomized controlled trials (RCTs) published or registered between 2019 and 2025. Meta-analyses were performed using a random-effects model, and risk of bias was assessed using the Cochrane risk of bias tool.

RESULTS: Ten RCTs involving 939 participants were included. LFD showed relatively consistent short-term efficacy (responder rate 34%-78%) with no significant difference versus other dietary interventions in pooled analysis (RR = 1.04, 95% CI: 0.91-1.19, P = 0.55, I2 = 0%). Mediterranean-based interventions, particularly MED-LFD, showed promising longer-term benefit in individual trials, with response rates of 81.5% and 70.4% at follow-up and superiority to TDA in one recent RCT (P = 0.007 and P = 0.004). TDA showed moderate efficacy (responder rate 42%-48.1%) but a lower pooled response rate than comparator dietary interventions (RR = 0.75, 95% CI: 0.64-0.88, P = 0.0005, I2 = 0%). SSRD showed favorable efficacy in habitual-diet-controlled trials and was non-inferior to LFD in one head-to-head trial, with better long-term adherence in descriptive follow-up data. GFD showed inconsistent efficacy, and pooled analysis did not demonstrate a significant advantage over comparator interventions (RR = 1.19, 95% CI: 0.83-1.70, I2 = 0%). TDA had the highest acceptability, and no serious adverse events were reported across included studies.

CONCLUSION: The available evidence suggests that the four dietary intervention categories examined in this review have different efficacy, acceptability, and safety profiles. LFD may provide relatively consistent short-term symptom benefit, Mediterranean-based approaches may be promising for longer-term management, TDA may offer practical advantages despite lower pooled efficacy, and SSRD may represent a promising alternative to LFD. GFD may benefit only a subset of patients rather than the general IBS population. Larger, well-designed RCTs are needed to confirm these findings and clarify subgroup-specific responses. Prospero registration: CRD420261335612,https://www.crd.york.ac.uk/PROSPERO/view/CRD420261335612.