Associations between vitamin intake and depression severity: A cross-sectional analysis of NHANES 2005-2014

Prior observational studies on vitamins and depression have shown conflicting results and limited generalizability. This study evaluated associations between individual vitamin intake and depression using nationally representative data from the National Health and Nutrition Examination Survey (NHANES).

NHANES 2005-2014 data were analyzed. Depression was assessed using the PHQ-9, and dietary intake was measured through 24-h recall and laboratory assays. A composite nutritional score was created from vitamin and nutrient data. Logistic regression models were used to estimate associations between vitamin intake and depression, adjusting for demographic, socioeconomic, and health factors.

Depressive symptoms (PHQ-9 ≥ 5) were present in about 25% of participants. Despite observed associations between several vitamins and depression in crude models, most vitamins were not associated with depression presence or severity after adjusting for demographic, socioeconomic, behavioral, and health-related covariates, though small effects persisted for Vitamin B6 (adjusted OR for moderate+ depression = 0.99; 95% CI: 0.98-1.00).

Only weak vitamin-depression associations were observed, and most diminished after adjusting for confounders. These findings may reflect broader differences in dietary patterns, demographic characteristics that influence health, and health behaviors, as observed in the adjusted results. Interpretation is limited by differences in data-collection timing across specific vitamins and by the lack of prospective data needed to evaluate temporality.