Modulation of the Gut–Kidney Axis Through Probiotics and Synbiotics in Chronic Kidney Disease: A Narrative Review

Abstract

Chronic kidney disease (CKD) is associated with increased cardiovascular morbidity and mortality, partly mediated through disruption of the gut–kidney axis. Gut microbiota dysbiosis contributes to the accumulation of uremic toxins, systemic inflammation, and oxidative stress, thereby accelerating CKD progression. This narrative review summarizes current evidence on the role of probiotics and synbiotics in modulating the gut–kidney axis in CKD. Literature was identified through searches of PubMed/MEDLINE, Scopus, Web of Science, and the Cochrane Library up to April 2025, with emphasis on randomized controlled trials, systematic reviews, meta-analyses, and mechanistic studies. Current evidence indicates that probiotics and synbiotics may improve gut microbial balance, enhance short-chain fatty acid production, and reduce circulating uremic toxins and inflammatory markers. Additional approaches, including dietary interventions, fecal microbiota transplantation, and pharmacological modulation of the microbiome, have also shown potential benefits. However, despite favorable effects on surrogate biomarkers, evidence demonstrating significant improvements in kidney function and long-term clinical outcomes remains limited. Further well-designed randomized controlled trials with standardized formulations and clinically relevant endpoints are required to establish the therapeutic role of gut microbiota modulation as an adjunctive strategy in CKD management.