Low-carbohydrate diet macronutrient quality and depression symptoms among US adults

The association between the quality of low-carbohydrate diets (LCDs) and depression symptoms remains underexplored. This study investigates the effects of LCDs on depression symptoms, with a specific focus on distinguishing the quality and quantity of macronutrients.

In this cross-sectional study, 28,791 participants aged ≥20 were involved. Three LCD scores were constructed based the quality and quantity of macronutrients: overall LCDs (OLCDs), healthy LCDs (HLCDs: characterized by reduced intake of low-quality carbohydrates [e.g., refined sugars], higher plant-based proteins, and unsaturated fats), and unhealthy LCDs (ULCDs: characterized by reduced intake of high-quality carbohydrates [e.g., whole grains], higher animal proteins, and saturated fats). The associations between LCD patterns and depression symptoms were evaluated using multivariable logistic regression. A restricted cubic spline (RCS) regression model was used to estimate the dose-response relationship.

Comparing extreme quartiles of HLCDs, the adjusted odds ratio (OR) (95 % CI) for depression was 0.70 (0.57, 0.86) (P-trend <0.001). No statistical significance was observed in ULCDs and depression symptoms. Non-linear relationships were identified for OLCDs (P-non-linear = 0.017), HLCDs (P-non-linear <0.001), with depression symptoms.

Macronutrient quality modifies LCD-depression associations, with healthier patterns showing inverse correlations. Our finding indicates inverse association between HLCDs and depression risk. Further longitudinal or interventional studies are required to validate these findings and explore mechanistic pathways.