Low-carbohydrate-diet score, dietary macronutrient intake, and depression among adults in the United States

The aim was to ascertain whether low-carbohydrate-diet (LCD) score and dietary macronutrient intake are associated with depression.This cross-sectional study included 23,204 United States adults from the National Health and Nutrition Examination Survey (NHANES) 2005-2018. Dietary macronutrient intake was evaluated by the average of two 24-h dietary recall interviews. LCD score was calculated by summing the 11 quantiles values of the percentages of energy derived from carbohydrate, protein, and fat. Major depression was defined as a nine-item Patient Health Questionnaire score of 10 or more. Logistic regression and restricted cubic spline models were used to explore the relationship between LCD score, dietary macronutrient intake, and depression.LCD score was significantly associated with the risk of depression after adjustment for covariates (odds ratio, 0.98; 95 % confidence interval, 0.97-0.99; p < 0.001). Restricted cubic splines showed that the pattern of this inverse association was nonlinear. Among macronutrients, carbohydrate and protein intake was nonlinearly associated with the risk of depression, whereas fat intake was not related to the risk of depression. A decreased risk of depression was observed when the carbohydrate intake was moderate (45.3 %-59.1 %). The pattern of the association between protein intake and the risk of depression was L-shaped.LCD score was inversely associated with the risk of depression in a nonlinear manner in a nationally representative sample of adults from the United States. Furthermore, moderate carbohydrate intake and high protein intake were correlated with a lower risk of depression.