RESUMO
BACKGROUND: The use of specific dietary patterns to alleviate depressive symptoms has gained increasing recognition. The Composite Dietary Antioxidant Index (CDAI) is a crucial criterion for assessing antioxidant diets. We examined the relationship between CDAI and depression among overweight and obese adults through a cross-sectional study conducted in the United States. METHODS: We used weighted multivariate logistic regression models with subgroup analysis to study the relationship between CDAI and depression. Generalized additive models were used to determine whether there was a nonlinear association between them. We developed a two-piece linear regression model to calculate the inflection point utilizing a recursive strategy. RESULTS: After adjusting for confounding variables, the odds ratios (ORs; 95 % CI) for the correlation between CDAI and depression were 0.75 (0.67, 0.84). A saturation effect emerged for the overweight group, following which we calculated the inflection point for the overweight population, which displayed ORs (95 % CI) of 0.62 (0.47, 0.80) before the inflection point of 0.83 and the ORs (95 % CI) of 1.01 (0.77, 1.31) after 0.83. The interaction was statistically significant in the sex stratification of the obese population. CONCLUSIONS: Our study highlighted a negative association between CDAI and depression among overweight and obese adults. Saturation effects and sex differences were observed in the overweight population.