Meta-analysis of the effectiveness of fecal microbiota transplantation in the treatment of metabolic-associated fatty liver disease: A systematic review based on liver inflammation indicators and fat content

BACKGROUND: Metabolic-associated fatty liver disease (MASLD) affects over 25% of the global population, progressing from hepatic steatosis to fibrosis. Current therapies show limited efficacy, and gut microbiota dysbiosis via the gut-liver axis highlights fecal microbiota transplantation (FMT) as a novel intervention. METHODS: Following preferred reporting items for systematic reviews and meta-analyses guidelines, 8 randomized controlled trials were systematically selected from PubMed, Cochrane, Embase, and Web of Science (inception to September 2025). MASLD patients receiving FMT (any protocol) versus standard care were evaluated for alanine aminotransferase (ALT), aspartate aminotransferase (AST), proton density fat fraction, and body mass index (BMI). Risk of bias was assessed using Cochrane ROB 1.0. RESULTS: FMT significantly reduced ALT (mean difference MD = -6.81, 95% confidence interval -10.29, -3.33, P = .0001) and AST (MD = -7.13, -10.45, -3.80, P < .0001) versus standard care. Subgroup analysis revealed greater ALT improvement in patients aged <50 years (MD = -14.00, -22.79, -5.20, P = .002). Proton density fat fraction decreased markedly (MD = -3.50, -5.12, -1.87, P < .0001), while BMI showed no significant change (MD = -0.69, -1.49, 0.11, P = .09). CONCLUSION: FMT effectively improves hepatic inflammation and steatosis in MASLD, with age modulating ALT response. Lack of BMI improvement suggests localized liver effects rather than systemic metabolic impact, supporting FMT as a targeted adjunctive therapy.