Efficacy of probiotic and synbiotic supplementation on antibiotic use duration and risk of postoperative infection in patients undergoing gastrointestinal and cancer-related surgery: An umbrella review of meta-analyses

Objective This umbrella review was conducted to assess the certainty and validity of all available meta-analyses for intervention trials regarding the impact of any synbiotic and probiotic interventions on antibiotic use duration and postoperative infection risk in patients undergoing gastrointestinal and cancer-related surgery. Methods A comprehensive systematic search was done by applying Web of Science, PubMed/MEDLINE, and Scopus, until July 03, 2024. Effect sizes of synbiotic and probiotic interventions were recalculated by using a random effects model. The GRADE tool was used to determine evidence certainty. Results Fifty-two clinical trials (with 4101 participants: intervention = 2007, placebo = 2094) in thirty-four meta-analyses were selected to report the impact of synbiotic and probiotic interventions on antibiotic use duration and postoperative infection risk. The results suggested that probiotic supplementations (vs. placebo) significantly decreased antibiotic use duration (mean differences [MD]: −1.77 days, 95% CI: −3.15, −0.40, I2 = 98.0%; low evidence certainty, p = 0.011) and postoperative infection (relative risk [RR]: 0.51, 95% CI: 0.40, 0.64, I2 = 0.0%; High evidence certainty, p < 0.001) among patients undergoing surgery. Moreover, the outcomes indicated that synbiotic supplementation (vs. placebo) significantly decreased antibiotic use duration (MD: −3.56 days, 95% CI: −5.17, −1.95, I2 = 90.9%; low evidence certainty; p < 0.001) as well as reduced the risk of postoperative infection (RR: 0.64, 95% CI: 0.49, 0.83, I2 = 45.2%; Moderate evidence certainty, p = 0.001) among patients undergoing surgery. Conclusion The current review suggests that synbiotic and probiotic supplementations may have beneficial effects on antibiotic use duration and the risk of postoperative infection in patients undergoing gastrointestinal and cancer-related surgery. However, the results should be interpreted with caution due to the limitations in the certainty of available data and the predominantly cancer/GI population studied. © 2026 European Society for Clinical Nutrition and Metabolism.