A J-shaped association between Dietary Inflammatory Index (DII) and depression: A cross-sectional study from NHANES 2007–2018

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.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.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.Our study highlighted a J-shaped association between DII and depression in a nationally representative sample of adults from the United States.