The Impact of Vitamin D deficiency on Depression in Obese Adults

There are studies showing associations between hypovitaminosis D and obesity, obesity and depression, and hypovitaminosis D and depression. This study aims to investigate the relationship between vitamin D levels and depression status of patients followed in an obesity center.

This retrospective study included 107 obesity patients followed up and treated at an obesity center. Patients were divided into two groups as serum 25(OH)D level < 20 ng/mL (deficient) and ≥ 20 ng/mL (not deficient) and compared in terms of Beck Depression Inventory scores. Patients were also divided into two groups according to BDI scores < 17 and ≥ 17, and serum 25(OH)D levels were evaluated.

Patients at higher risk for depression (BDI score ≥ 17) had statistically significantly higher weight (p = 0.003) and BMI (p < 0.001), but had significantly lower serum 25(OH)D levels (p < 0.001). The BDI scores were found to be moderately positively related with the BMI (r = 0.404, p < 0.001), weakly negatively related with vitamin D levels (r = -0.383, p < 0.001), weakly positively related with weight (r = 0.293, p = 0.002). The BDI score me-dians (12 and 8, respectively) were found to be statistically significantly higher in patients with serum 25(OH)D levels of < 20 ng/mL compared to those with ≥ 20 ng/mL (p < 0.001). The increased BMI and decreased serum 25(OH)D levels have been found to independently increase the risk of depression in multivariate logistic regression analysis. The ROC analysis performed to evaluate the discriminative performance of serum 25(OH)D levels in predicting the risk of depression. The analysis showed that the serum 25(OH)D parameter was likely to reveal patients who were at higher risk for depression. For the cutoff point of 25(OH)D ≤ 19.21 level determined by Youden index, the sensitivity was found as 92.86% and the selectivity as 68.82%.

In our study, the BMIs were higher and serum 25(OH)D levels were lower in obese individuals at risk for depression. Understanding or explaining the relationship between vitamin D deficiency and depression will contribute to revealing the preventive or therapeutic role of vitamin D supplementation for depression.