Prophylactic probiotics and synbiotics for prevention of diarrhea in adults receiving enteral nutrition: A systematic review and meta-analysis.

Background

Diarrhea is a frequent complication during enteral nutrition (EN) in adults and may interrupt feeding, prolong hospitalization, and increase healthcare burden. Modulation of the intestinal microbiota with probiotics or synbiotics represents a potential preventive strategy, but the evidence remains uncertain.

Methods

This systematic review and meta-analysis followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines (PROSPERO: CRD420251183554). We searched PubMed, Embase, the Cochrane Library, Web of Science, CNKI, Wanfang, and CQVIP from database inception to November 6, 2025. Randomized controlled trials (RCTs) comparing prophylactic probiotics or synbiotics with placebo, routine care, or unsupplemented EN in adults were eligible. Risk ratios (RRs) with 95% confidence intervals (CIs) were pooled using random-effects models. Certainty of the evidence was assessed using the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach.

Results

Thirty-nine RCTs were included; 36 (3446 participants) contributed to meta-analysis. Probiotics or synbiotics reduced reported diarrhea versus controls (RR 0.35; 95% CI 0.29-0.42; p < 0.00001; I2 = 0%). However, I2 = 0% may reflect limited power with sparse events. Funnel plot asymmetry and Egger's test (p < 0.001) suggested possible publication bias. Most trials had high risk of bias (unblinded outcome assessment). Certainty was very low, downgraded mainly for serious risk of bias and suspected publication bias.

Conclusions

Very low-certainty evidence suggests probiotics or synbiotics may reduce reported diarrhea in adults on EN, but the true effect is likely smaller. Current data do not support routine use or specific recommendations. Larger, blinded trials with standardized definitions are needed.