Nutritional Interventions in Adult Patients With Irritable Bowel Syndrome: An Umbrella Review of Systematic Reviews and Meta-analyses of Randomized Clinical Trials.

CONTEXT: There is still debate regarding the effect of nutritional interventions in improving irritable bowel syndrome (IBS) symptoms. OBJECTIVES: The aim was to examine the evidence certainty and validity of all existing meta-analyses of intervention trials on nutritional interventions in patients with IBS. DATA SOURCES: Scopus, PubMed, and Web of Science were reviewed until June 2023. DATA EXTRACTION: Meta-analyses assessing the impacts of nutritional interventions in adults with IBS were entered. Effect sizes of nutritional interventions were recalculated by applying a random-effects model. GRADE (Grading of Recommendations, Assessment, Development, and Evaluation) was implemented to determine evidence certainty. RESULTS: A total of 175 trials in 58 meta-analyses were entered describing the effects of 11 nutritional interventions on IBS-related outcomes. Nutritional interventions had beneficial effects on some IBS-related outcomes. For instance, soluble fiber, peppermint oil, and aloe vera improved IBS symptoms, and vitamin D3 and curcumin improved IBS symptom severity. Tongxieyaofang improved abdominal pain severity and stool frequency. Nevertheless, these outcomes have mainly shown small effects and low to very low evidence certainty. With regard to abdominal pain after probiotic supplementation (relative risk [RR]: 4.04; 95% confidence interval [CI]: 2.36, 6.92; GRADE = moderate) and IBS symptoms after a low-fermentable oligosaccharides, disaccharides, monosaccharides, and polyols (FODMAP) diet (RR: 1.48; 95% CI: 1.14, 1.93; GRADE = moderate), there was evidence that probiotics and a low-FODMAP diet can confer clinical and favorable effects. CONCLUSION: The current review does not support nutritional interventions for improving IBS symptoms. With regard to probiotics and a low-FODMAP diet, considering limitations like short-term study duration, there was an influential clinical impact. SYSTEMATIC REVIEW REGISTRATION: PROSPERO registration no. CRD42023429991.