Vitamin D3 is produced in the skin after exposure to ultraviolet B light from the sun. Vitamin D3 is metabolised sequential in the liver into 25-hydroxy-vitamin D [25(OH)D], which is the storage form of vitamin D in the body, and then in the kidney into the steroid hormone, 1a,25-dihydroxyvitamin 1a,25-dihydroxyvitamin D [1,25(OH)2D].~At higher latitudes ultraviolet B light is stopped by the atmosphere during winter season. Half of Danes have low levels of [25(OH)D] in the blood and especially in the early spring months the levels of [25(OH)D] are low. In addition, Vitamin D3 is absorbed through the gut from vitamin D-rich food sources. But several studies show that it is not possible through a recommended diet, which consists of 300 g of fish per week to consume adequate amounts of vitamin D3.~New research suggests link between vitamin D3 and brain function.In the Central Nervous System (CNS) there are specific nuclear receptors for 1,25(OH)2D (VDR) and the enzymes necessary for the hydroxylation of 25(OH)D to 1,25(OH)2D are also present in CNS.~In clinical studies, low serum levels of 25(OH)D, have been associated with reduced cognitive function, anxiety and depression.~The objective of this randomized clinical trial is to investigate whether patients with depression should be offered vitamin D3 supplements, or it has no significance in relation to treatment outcomes.~The study is carried out in Mental Health Services in the Region of Southern Denmark for 24 weeks and offered to patients being treated for depression (treatment as usual) plus 70μg vitamin D3 or placebo.
The purpose of this study is to investigate whether patients with depression should be offered vitamin D supplements, or it has no significance in relation to treatment outcomes.