Vitamin D deficiency and depression in obese adults: NHANES 2009-2018

Vitamin D deficiency is common in obesity and has been linked to depression. However, the specific relationship between vitamin D status and depression in overweight or obese adults remains unclear.

This study aimed to evaluate the association between serum vitamin D levels and depression among obese adults using data from NHANES 2009-2018.

Cross-sectional analysis of NHANES 2009-2018, a nationally representative survey with a multistage, stratified, cluster design; analyses incorporated survey weights. Of 49,693 participants, we excluded those aged < 18 or > 60 years (n = 28,464), those with BMI < 30 kg/m² (n = 13,582), and records missing serum 25(OH)D (n = 371) or PHQ-9 (n = 2,454), yielding a final analytic sample of 4,822. Depression was assessed with the PHQ-9 (scores ≥ 10). Associations between serum 25(OH)D and depression were estimated using survey-weighted multivariable logistic regression, with exploratory subgroup analyses. NHANES protocols were approved by the National Center for Health Statistics (NCHS) with written informed consent.

A total of 4,822 subjects (mean age 41 years; 44% male) were included in this study, in which the prevalence of depression was 20%. The results of the study showed that the detection rate of vitamin D insufficiency/deficiency was 16% in the depressed group, which was significantly higher than the 12% in the non-depressed group (P = 0.002). After adjusting for age, gender, race, education level, marital status, poverty-to-income ratio, smoking, alcohol consumption, hours of sleep, diabetes, hypertension, and number of hyperlipidemia, there remained a significant positive association between depression and serum vitamin D insufficiency/deficiency (adjusted OR = 1.41, 95%CI 1.06, 1.88).

In this cross-sectional analysis of NHANES 2009-2018 obese adults, vitamin D insufficiency/deficiency was associated with higher odds of depression; causality cannot be inferred.