The association between gut microbiota and metabolic dysfunction-associated steatotic liver disease (MASLD): a case-control study.

BACKGROUND: Non-alcoholic fatty liver disease (NAFLD) is a growing concern among children and adolescents, with emerging evidence highlighting the role of gut microbiota in its pathogenesis. This case-control study aimed to explore the association between gut microbiota composition and NAFLD in overweight and obese Iranian children and adolescents. Given the recent updates in nomenclature, we refer to NASLD as metabolic dysfunction-associated steatotic liver disease (MASLD), in accordance with new international consensus. METHODS: A total of 66 participants, including 33 MASLD cases and 33 controls, with a case control study design were enrolled. MASLD diagnosis was done using an ultrasonography scan of the liver and gastroenterologist confirmation. Furthermore, gut microbiota composition was analyzed using real-time PCR, and metabolic, anthropometric, and dietary data were collected. RESULTS: The mean age of the study population (39.4% girl) was 136.82 month and mean BMI Z-score was 3.05. Regarding the gut microbiota composition, the only considerable variation was the lower abundance of Coprococcus genera in the MASLD group. Based on the analysis in the crude model and with adjustments for age, sex, and BMI, an inverse correlation was detected between the number of Coprococcus bacteria and the odds of MASLD(OR = 0.87, 95% CI: 0.77-0.98; P trend = 0.032 and OR = 0.81, 95% CI: 0.67-0.99; P trend = 0.046, respectively). However, this correlation was no longer present in the fully adjusted model. Furthermore, a negative correlation was noted between Coprococcus and ALT levels. On the other hand, the Prevotella bacteria represented significant positive correlations with both ALT and AST levels. CONCLUSION: Significant differences in gut microbiota composition were observed between MASLD and control groups, including reduced SCFA-producing and increased pro-inflammatory bacteria. These findings highlight the microbiota's potential role in MASLD pathogenesis, though confirmation in larger cohorts is needed.