Study identified a strong and significant association between the risk of depression and levels of Vitamin D in the blood, the findings of this study cannot prove that low levels of Vitamin D in the blood directly cause depression. There could be other explanations for this finding, including decreased exposure to sunlight which is, itself, linked to depression (the majority of the Vitamin D in our bodies is manufactured in our skin, following exposure to sunlight). However, recent research has also demonstrated that cellular receptors for Vitamin D are present within the brain, including those areas of the brain that regulate mood, and which are also thought to be the areas of the brain responsible for mood disorders like depression. Therefore, it is certainly possible that Vitamin D, like multiple other hormones and neurotransmitters, may also play a direct role in the modulation of our mood. 
Mood Disorders
