Abstract
<jats:p>Background: The coexistence of obesity and chronic kidney disease (CKD) is increasingly recognized as a clinically complex syndrome mediated, in part, by profound gut microbiota dysbiosis. Synbiotics—combined preparations of probiotics and prebiotics—represent a rational intervention capable of targeting microbial composition, intestinal barrier integrity, and host immune modulation. Methods: A prospective, randomized, double-blind, placebo-controlled trial was conducted in 120 adult patients (BMI ≥30 kg/m², eGFR 15–59 mL/min/1.73 m²) over 12 weeks. Participants received either a multi-strain synbiotic formulation (Lactobacillus acidophilus NCFM, Bifidobacterium longum BB536, Lactobacillus rhamnosus GG, 10¹⁰ CFU/day + 10 g fructooligosaccharides) or matched placebo. Results: Synbiotic supplementation significantly increased microbiota alpha diversity (Shannon index: +1.23±0.31 vs. −0.04±0.18; p<0.001) and reduced serum indoxyl sulfate by 28.4% (p<0.001), p-cresyl sulfate by 24.1% (p=0.003), and hs-CRP by 31.2% (p<0.001). The rate of eGFR decline was attenuated (−1.2 vs. −3.8 mL/min/1.73 m²; p=0.007). Significant improvements in BMI, HOMA-IR, and SF-36 vitality scores were also recorded. Conclusion: Synbiotic supplementation produces clinically meaningful improvements in gut microbiota composition, uremic toxin burden, systemic inflammation, and renal functional trajectory in obesity-CKD comorbidity, supporting their integration into multimodal management protocols pending confirmation in larger trials.</jats:p>