The Association Between Serum Vitamin D and Lipid Levels in Patients With Depression: A Cross-Sectional Study

Background: Vitamin D deficiency is prevalent among individuals with depression; however, clinical findings regarding this association have been inconsistent. Additionally, a significant proportion of depressed patients present with dyslipidemia, yet the interplay between vitamin D status, lipid metabolism, and depression remains poorly understood. We aimed to explore the role of vitamin D in depression and to investigate the potential associations between vitamin D status, lipid metabolism, and depressive symptoms. Methods: We recruited 412 first-episode, drug-naïve patients with depression and 180 age-matched healthy controls. Fasting venous blood samples were collected in the morning to quantify serum vitamin D and lipid profiles. Depressive symptoms were assessed on the day of blood collection using both the Patient Health Questionnaire-9 (PHQ-9) and the 17-item Hamilton Depression Rating Scale (HAMD-17). Spearman's rank correlation was employed to examine associations between serum vitamin D concentrations and depressive symptom severity. Binary logistic regression analysis was subsequently performed to identify potential risk factors for depression. Results: Compared with healthy controls, depressed patients had significantly lower serum vitamin D and high-density lipoprotein cholesterol (HDL-C) levels. This sex-specific pattern showed that male patients had lower vitamin D, while female patients had lower HDL-C. Spearman's correlation analysis revealed significant inverse correlations of vitamin D and triglyceride (TG) with PHQ-9 and HAMD-17 scores among depressed patients. Logistic regression analysis indicated that individuals with higher vitamin D levels had a reduced likelihood of depression compared with those with low vitamin D levels (adjusted odds ratio (OR) = 0.950, 95% confidence interval (CI): 0.920–0.982, p = 0.002). Similarly, subjects with elevated HDL-C levels were associated with a lower likelihood of depression relative to those with diminished HDL-C levels (adjusted OR = 0.317, 95% CI: 0.173–0.583, p < 0.001). Conclusion: Serum vitamin D and HDL-C levels were lower in patients with depression than in healthy individuals. Both vitamin D and HDL-C may be inversely associated with depression.