An Observational Clinical Study on the Association of Intestinal Ruminococcus Gnavus and Its Derived Biogenic Amines With Metabolic Dysfunction-associated Fatty Liver Disease

Inclusion Criteria: * 1.Healthy individuals without a history of liver disease or related underlying diseases; or patients diagnosed with metabolic dysfunction-associated fatty liver disease (MAFLD) according to the latest guideline, Guidelines for the Prevention and Treatment of Metabolic (Dysfunction-Associated/Non-Alcoholic) Fatty Liver Disease (2024 Edition), meeting the following criteria: (i) imaging-based diagnosis of fatty liver and/or liver biopsy showing ≥5% macrovesicular steatosis in hepatocytes; (ii) presence of at least one component of metabolic syndrome (MetS); and (iii) exclusion of other causes of fatty liver, including excessive alcohol consumption (weekly ethanol intake ≥210 g for men and ≥140 g for women), malnutrition, hepatolenticular degeneration (Wilson's disease), and other potential etiologies. 2.Willingness to participate in this study and to sign the informed consent form. 3.Age \>18 years. Exclusion Criteria: * 1\. History of severe organic diseases in the liver, gastrointestinal tract, kidneys, or other systems, malignant tumors, or autoimmune diseases. 2\. Patients who have had an acute infection or inflammatory disease within the past month. 3\. Use of laxatives, antibiotics, probiotics, prebiotics, proton pump inhibitors, or other medications that may affect the gut microbiota within the past month.