The Association of Body Mass Index and Serum Vitamin D level with Depression
Keywords:
Obesity, Vitamin D, deficiency, Depression, SeverityAbstract
Background:
Emerging evidence suggests that vitamin D deficiency and obesity may contribute to the pathophysiology of depression through neuroendocrine and inflammatory mechanisms.
Objective: To compare serum 25-hydroxyvitamin D and body mass index between patients with depression and healthy controls, and to assess their association with depression severity.
Subjects and Methods:
A case-control study conducted at Al-Hakeem Hospital, Al-Najaf, Iraq, from February to August 2025. Included 120 participants; 70 patients diagnosed with depression and 50 age- and BMI-matched healthy controls. Serum 25(OH)D levels were measured using the Hipro AFS-1 immunoassay system. Statistical analysis was performed using SPSS v26, with p < 0.05 considered significant.
Results:
A significant lower median value of serum 25(OH)D levels in patients with depression, compared to healthy controls; 17.50 vs. 22 ng/ml, respectively, (p =0.001). No significant differences in mean age and BMI values between patients and controls (p > 0.05). The median 25(OH)D level was significantly lower in patients with moderate and severe depression compared with both controls (p = 0.0043 and p = 0.0001, respectively) and the mild group (p = 0.0007 and p = 0.0001, respectively). The severe depression group showed the lowest median vitamin D levels, significantly lower than the moderate group (p = 0.0099). In contrast, the mild depression group did not differ significantly from controls. Correlation analysis revealed significant negative correlation between age and 25(OH)D levels in the mild group (r = –0.519, p = 0.0093) and significant negative correlation between BMI and 25(OH)D levels in the severe depression group (r = –0.473, p = 0.0263).
Conclusion: Depression is strongly associated with reduced serum vitamin D levels, and this association is more pronounced with increasing severity of depression.
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