A J-shaped association between Dietary Inflammatory Index (DII) and depression: A cross-sectional study from NHANES 2007-2018. Journal of affective disorders BACKGROUND:Growing evidence indicates that depression is more common in people who partake in a pro-inflammatory diet. The objective of our study was to assess the association between the Dietary Inflammatory Index (DII) and depression through a cross-sectional study of the National Health and Nutrition Examination Survey from 2007 to 2018. METHODS:We used weighted multivariable logistic regression models with subgroup analysis to explore the relationship between DII and depression. Generalized additive models were used to test whether there was a nonlinear association. Then, we constructed a two-piece linear regression model and performed a recursive algorithm to calculate the inflection point. RESULTS:The study enrolled a total of 30,627 individuals from the United States. In the regression model with full confounding variables adjusted, the OR (95 % CI) for the association between DII and depression was 1.05 (1.04, 1.06). A J-shaped association was found between DII and depression, with a turning point of 2.74. After the turning point, the OR (95 % CI) was 1.60 (1.51, 1.69). Only the interaction in the cardiovascular disease (CVD) analysis was statistically significant. CONCLUSION:Our study highlighted a J-shaped association between DII and depression in a nationally representative sample of adults from the United States. 10.1016/j.jad.2022.11.052