Dietary antioxidant capacity, flavonoid subclasses, and metabolic dysfunction-associated fatty liver disease in overweight and obese youth.

BACKGROUND: Metabolic dysfunction-associated fatty liver disease (MAFLD) is a growing public health concern among children and adolescents with overweight and obesity. Diet quality, particularly antioxidant intake, may play a role in hepatic metabolic regulation. This study investigated the association between dietary total antioxidant capacity (DTAC) and MAFLD, and examined the mediating role of flavonoid subclasses. METHODS: In this cross-sectional study, 505 overweight and obese Iranian children and adolescents aged 7-18 years were recruited. DTAC was estimated using a validated 147-item food frequency questionnaire and the ferric reducing antioxidant power (FRAP) method. MAFLD was diagnosed via ultrasonographic evidence of hepatic steatosis in combination with overweight/obesity. Logistic regression and restricted cubic spline models assessed associations, and mediation analysis evaluated indirect effects of flavonoids. RESULTS: The mean DTAC was 8.7 ± 3.8 overall, 8.3 ± 3.3 in the MAFLD group, and 9.0 ± 4.1 in the non-MAFLD group. In fully adjusted model, participants in the highest DTAC tertile had 62% reduced odds of MAFLD compared to the lowest tertile (OR: 0.38; 95% CI: 0.18-0.82; P-trend = 0.03). Spline analysis confirmed a non-linear inverse association. Mediation analysis revealed that flavonols and anthocyanidins significantly mediated the DTAC-MAFLD relationship, accounting for 74.4% and 38.4% of the total effect, respectively. CONCLUSION: Higher dietary antioxidant capacity is inversely associated with MAFLD in overweight and obese youth, partly through the intake of specific flavonoid subclasses. These findings emphasize the value of antioxidant-rich diets for pediatric liver health and highlight the need for longitudinal studies or clinical trials to confirm causal relationships.