S2073 Comparison of Probiotic vs Prebiotic Supplementation in Gut Microbiome Reconstitution: Systematic Review and Meta-Analysis

Introduction: The gut microbiome plays a vital role in maintaining immune, metabolic, and gastrointestinal health. Dysbiosis or microbial imbalance, contributes to many chronic diseases. Dietary interventions, such as probiotics (live microorganisms) and prebiotics (non-digestible compounds that stimulate beneficial microbes), have increased exponentially to restore microbial balance. This systematic review evaluates the efficacy of probiotic vs prebiotic supplementation in reconstituting gut microbiome function and diversity. Methods: Four reviewers independently searched 4 different resources published in the last 10 years that evaluated probiotic or prebiotic supplementation in adults, with preset inclusion and exclusion criteria. The risk of bias was assessed independently using the Cochrane tool, with disagreements resolved. Results: Probiotics significantly increased Lactobacillus and Bifidobacterium populations (SMD: 0.48; 95% confidence interval [CI]: 0.30–0.66; I² = 20%), with mild improvements in GI symptoms (bloating, stool consistency). Effects on microbial diversity were modest and inconsistent (SMD: 0.18; 95% CI: −0.01 to 0.37; I² = 45%). Short-chain fatty acid levels showed no significant change. Inflammatory markers (C-reactive protein, IL-6) decreased slightly (SMD: −0.22; 95% CI: −0.39 to −0.05; I² = 30%). Prebiotics, primarily inulin, galactooligosaccharides, and resistant starch, resulted in a increase in overall microbial diversity (SMD: 0.53; 95% CI: 0.35–0.70; I² = 25%) and SCFA production, particularly butyrate (SMD: 0.40; 95% CI: 0.21–0.59; I² = 28%) and also significantly reduced systemic inflammation (SMD: −0.37; 95% CI: −0.52 to −0.22; I² = 15%) and endotoxin levels. Clinically, they improved stool frequency and consistency more consistently than probiotics. There were no reports of serious adverse events in either group. Conclusion: Both probiotics and prebiotics positively affect gut microbiota, but they operate through different mechanisms. Prebiotics appear more effective for comprehensive microbiome reconstitution by enhancing microbial diversity and metabolic function. Probiotics may be preferable for targeted strain support and immune regulation. More randomized controlled trials are needed to refine the therapeutic use and guide personalized microbiome-based interventions.