Assessing the Efficacy of Functional Food as Treatment for Irritable Bowel Syndrome with Constipation: A Systematic Review and Network Meta-Analysis

Context Functional foods possess the ability to modulate intestinal motility, microbiota equilibrium, and inflammatory status, positioning them as promising nonpharmacological interventions for irritable bowel syndrome with constipation (IBS-C). Objective This meta-analysis and systematic review aimed to identify the most efficacious functional foods for managing IBS-C through network meta-analysis. Data Sources A comprehensive search of Embase, PubMed, Cochrane Registry of Controlled Trials, and Web of Science databases was conducted from inception to April 16, 2025. Data Extraction Randomized controlled trials (RCTs) evaluating the therapeutic effects of functional foods on IBS-C were included. The Grades of Recommendations Assessment, Development and Evaluation minimal contextualization framework was used to assess the certainty of evidence. We used the Risk-of-Bias Tool (version 2) to assess the quality of the literature. The primary outcome was IBS-C–related abdominal pain; secondary outcomes included IBS-related quality of life (QOL), abdominal distension, defecation frequency, and stool consistency scores. Data Analysis After screening 1085 articles, 12 RCTs ultimately were included. Network meta-analysis results demonstrated natural fruits were more effective than dietary fiber in alleviating abdominal pain (MD, -0.23 [95% credible interval (CrI), -0.45 to -0.01]; high-certainty evidence, category 1). Compared with placebo, natural fruits (MD, 7.52 [95% CrI, 1.59-13.40]; high certainty, category 1), dietary fiber (MD, 7.13 [95% CrI, 0.75-13.46]; low certainty, category 1), and inulin-based composite foods (MD, 5.40 [95% CrI, 0.49-10.30]; high certainty, category 1) significantly improved patients’ QOL. The surface under the cumulative ranking curve ranking indicated natural fruits were the most effective functional foods for improving both abdominal pain and QOL in IBS-C. Conclusion Natural fruits, such as kiwis and figs, represent the most efficacious functional foods for managing IBS-C. Dietary fiber and inulin-based composite foods have also demonstrated a significant positive impact on improving QOL in IBS-C. Systematic Review Registration: PROSPERO registration No. CRD420251037710