All vitamins and minerals are essential to life. However, Vitamin D is most curious because it is involved in so many aspects of physical well being, and that while all around us, populations in the industrialized nations are predominately deficient in it. How could this be?
In the late 1970s, government warned about holes in the ozone that would cause skin cancer if you stayed in the sun too long and/or you did not use Sun Screen Block. Well, most people listened and as a result people started blocking the life giving light of the sun, which includes the photosynthesis of vitamin D in the skin.
Vitamin D promotes production of antimicrobial peptides, these are important members of the host defense system.* Vitamin D promotes the adaptive immune system, which is that part of the immune system that constantly needs to adjust for an ever changing environment; like summer to winter.*