Vitamin D: Between the brightness of the sun and the darkness of depression

The scientific literature suggests a relationship between vitamin D (VitD) and the onset, treatment and prognosis of depression. However, this line of research continues to be controversial. The aim of the study was to analyse the relationship between depression and VitD values, controlling for the influence of the season.

Observational and cross-sectional study. The sample was made up of 150 adult female volunteer participants (aged between 28 and 78 years). The sample was stratified into three groups: a) depression without treatment, b) depression under treatment with antidepressants, and c) without depression (control). VitD values (ng/ml) were compared.

Significant differences were found between the three groups surveyed. The group of participants with depression without treatment obtained the lowest VitD values (mean 18.62ng/ml; SD 8.42), compatible with severe insufficiency. The group of participants with depression in treatment obtained higher values than the previous group, although in an insufficient range (mean 23.80ng/ml; SD 11.30). The third group (control) obtained the highest values and in accordance with the desirable range (mean 30.19ng/ml; SD 10.21). There were no age differences between the groups. When controlling for possible effects of the season, the previous differences in VitD between the three groups were maintained, with an evident decrease of all the mean levels in the winter period.

Depression is associated with insufficient VitD values. Treatment with antidepressants improves these values, although they continue to be insufficient. The findings of this study reinforce the evidence for an association between depression and VitD.