Abstract
BACKGROUND: Probiotic interventions are increasingly considered for alleviating gastrointestinal disorders such as diarrhea, nausea, bloating, and epigastric discomfort. This umbrella meta-analysis aims to resolve inconsistencies in existing research and offers a comprehensive assessment of probiotics' impact on these gastrointestinal symptoms. METHODS: We conducted an extensive literature search across PubMed, Scopus, Web of Science, and Google Scholar (up to June 2024), including meta-analyses of interventional studies investigating probiotics' effects on gastrointestinal disorders. Pooled effect sizes with 95% confidence intervals were derived using a random-effects model, accompanied by subgroup and sensitivity analyses. The certainty of evidence and study quality were evaluated using AMSTAR 2 tools. RESULTS: Probiotic supplementation was associated with a significant reduction in the risk of diarrhea (RR 0.44; 95% CI 0.37-0.52), nausea (RR 0.59; 95% CI 0.49-0.60), epigastric pain (RR 0.71; 95% CI 0.56-0.87), bloating (RR 0.74; 95% CI 0.64-0.84), and taste disturbance (RR 0.55; 95% CI 0.36-0.75), all with p-values < 0.001. Subgroup analyses revealed more pronounced effects in studies with shorter intervention durations (≤ 2-4 weeks), and multi-strain formulations, particularly for diarrhea and epigastric pain. However, moderate to high heterogeneity and generally low methodological quality among several included meta-analyses limit the robustness of the findings. CONCLUSION: This umbrella meta-analysis demonstrates the potential effectiveness of probiotics in alleviating gastrointestinal symptoms. However, the findings should be interpreted with caution due to moderate to high heterogeneity and the generally low methodological quality of many included studies.