A nested case-control study on the relationship between gut microbiota and non-alcoholic fatty liver disease.

Background: The gut microbiota plays an important role in non-alcoholic fatty liver disease (NAFLD). This study aimed to explore gut microbiota-associated biomarkers for incident NAFLD and evaluate their predictive value, providing preliminary evidence for early risk identification. Methods: From an initial cohort of 1,772 participants, 404 were included in the final analysis, comprising 101 incident NAFLD cases and 303 age-matched controls (1:3). Gut microbiota composition and function were characterized by metagenomic sequencing. Microbial features were compared between participants who developed NAFLD (NAFLD -/+) and those who did not (NAFLD -/-). A CatBoost model integrating gut microbiota, functional pathways, and clinical indicators was constructed to predict NAFLD, with a random forest (RF) model on the same features for comparison. Progressively enriched feature sets assessed the incremental value of microbiota-related features beyond clinical indicators, and SHapley additive exPlanations (SHAP) values interpreted the model outputs. Results: The NAFLD (-/+) group had significantly lower species-level beneficial gut microbiota ( Conclusion: Gut microbiota alterations may serve as potential early biomarkers for incident NAFLD and contribute to its pathogenesis. The CatBoost model integrating multi-omics and clinical data shows moderate predictive ability, supporting the potential of gut microbiota-based approaches for non-invasive risk stratification.