Bergman P. J Intern Med 2020.
Vitamin D is produced in the skin under the influence of UVB-light from the sun or obtained via the diet by eating fatty fish, enriched dairy products or supplements. Vitamin D is known to support a healthy bone and severe deficiency may lead to osteomalacia or the rickets, which still occur in poor areas of the world. In addition, vitamin D support key functions in many organs, including the brain, muscle and the immune systems (Holick, 2007). In fact, the vitamin D receptor (VDR) is expressed in most cell types and may activate somewhere between 200-500 genes, many related to the immune system.