The Role of Vitamin D Supplementation on Well Being and Symptoms of Depression During the Winter Season in Health Service Staff

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 indoor employees, with tendency to depressive symptoms in the winter season, should be offered vitamin D3 supplements during the Winter season, or it has no significance in relation prevent depressive symptoms.