EP383 - Probiotics and Symbiotics in the Management of Patients with Diarrhea-Predominant Irritable Bowel Syndrome: An Updated Systematic Review and Meta-analysis

Purpose/Background: Diarrhea-predominant irritable bowel syndrome (IBS-D) is a chronic gastrointestinal disorder characterized by abdominal pain, altered stool consistency, and impaired quality of life. Conventional therapies often provide incomplete relief, leading to growing interest in gut-directed therapies such as probiotics and symbiotics. These agents may modulate the gut microbiota and gut-brain signaling, thereby improving gastrointestinal symptoms. This systematic review and meta-analysis aimed to evaluate the efficacy of probiotics and synbiotics in reducing abdominal pain, improving global symptoms, and modifying stool output in patients with IBS-D.

Methods/Interventions: This PRISMA 2020 - compliant systematic review and meta-analysis was registered in PROSPERO (CRD42025643966). A comprehensive search was performed in PubMed, Embase, Web of Science, and Cochrane Central from inception to February 2025. Only randomized controlled trials (RCTs) enrolling patients with IBS-D were included. Data were pooled using random-effects models. The primary outcomes were abdominal pain, global symptoms, stool frequency and stool consistency.

Results/Outcomes: Twenty-six RCTs, including 2272 patients, met the inclusion criteria. Overall, probiotic and symbiotic therapy was associated with a significant reduction in abdominal pain (SMD −0.40; 95% CI −0.54 to −0.27; p < 0.01; I² = 45%) and a significant improvement in global symptoms (SMD −0.58; 95% CI −0.75 to −0.41; p < 0.01; I² = 58%). For stool frequency, the results showed a significant reduction (SMD −0.28; 95% CI −0.42 to −0.14; p < 0.01; I² = 0%). No significant difference was observed for stool consistency (SMD −0.30; 95% CI −0.76 to 0.16; p = 0.12; I² = 86%). Subgroup analysis showed that isolated probiotics significantly improved abdominal pain (SMD −0.48; 95% CI −0.69 to −0.27; I² = 60%), global symptoms (SMD −0.53; 95% CI −0.72 to −0.34; I² = 55%) and stool frequency (SMD −0.45; 95% CI −0.70 to −0.21; I² = 0%) but had no significant effect on stool consistency (SMD −0.49; 95% CI −1.10 to 0.11; I² = 89%). Combined probiotics also significantly improved abdominal pain (SMD −0.33; 95% CI −0.49 to −0.16; I² = 14%) global symptoms (SMD −0.64; 95% CI −0.93 to −0.36; I² = 64%) and stool frequency (SMD −0.20; 95% CI −0.37 to −0.03; I² = 0%) but did not significantly affect stool consistency (SMD 0.19; 95% CI −0.17 to 0.55; I² = 35%).

Conclusion/Discussion: Probiotics and symbiotics significantly improve abdominal pain, global symptoms and stool frequency in IBS-D patients, supporting their role as a non-pharmacological adjunct therapy. Effects on stool consistency were not statistically significant, likely reflecting strain-specific differences and study heterogeneity. Larger, high-quality, strain-targeted RCTs are warranted to define optimal formulations and responder profiles.

Figure 1: Forest plot reporting abdominal pain outcome; Figure 2: Forest plot demonstrating global symptoms outcome.
Figure 1: Forest plot reporting abdominal pain outcome; Figure 2: Forest plot demonstrating global symptoms outcome.
Figure 3: Forest plot showing stool frequency outcome; Figure 4: Forest plot demonstrating stool consistency outcome.
Figure 3: Forest plot showing stool frequency outcome; Figure 4: Forest plot demonstrating stool consistency outcome.