Metabolic Dysfunction-Associated Steatotic Liver Disease: An Update Narrative Review of the Therapeutic Potential of Combining Probiotics and Metformin.

Metabolic dysfunction-associated steatotic liver disease (MASLD) has replaced older exclusion-based terminology as the preferred term for steatotic liver disease associated with cardiometabolic risk factors. MASLD is now among the most common causes of chronic liver disease and may progress from simple steatosis to metabolic dysfunction-associated steatohepatitis (MASH), fibrosis, cirrhosis, and hepatocellular carcinoma. This updated rigorous narrative review synthesizes current evidence on MASLD diagnosis and management, with emphasis on the gut-liver axis and the therapeutic potential of combining probiotics with metformin. A structured narrative search was conducted in PubMed, PMC, ScienceDirect, Taylor & Francis, Cochrane Library, and Google Scholar using the keywords "MASLD", "MAFLD", "NAFLD", "MASH", "probiotics", "synbiotics", "metformin", and "gut-liver axis". The review was designed as a narrative synthesis rather than a systematic review. Current guidance supports stepwise risk stratification using serum fibrosis scores followed by elastography or advanced imaging when indicated. Ultrasonography remains accessible but has limited sensitivity for mild steatosis, is operator-dependent, and is not sufficient for comprehensive assessment of fibrosis or disease activity. Metformin is appropriate for type 2 diabetes mellitus and improves insulin resistance, but current guidelines do not recommend it as a targeted treatment for MASH because histological benefit has not been consistently demonstrated. Probiotics and synbiotics may improve aminotransferases, inflammatory markers, lipid parameters, intestinal barrier function, and gut dysbiosis; however, findings vary by strain, formulation, dose, treatment duration, population, and endpoint. The combination of probiotics and metformin is mechanistically plausible because it targets both metabolic dysfunction and intestinal dysbiosis, but human evidence remains limited. Larger, strain-specific, adequately powered trials using standardized MASLD criteria and clinically meaningful endpoints are required before routine clinical recommendations.