Fact - functionally it's more like a hormone than a vitamin;
Fact - the term 'Vitamin D' actually refers to several related vitamin variants, not just one;
Fact - its formation requires more participation from the body than any other vitamin does. Vitamin D is often called the 'sunshine' vitamin. Why? It's produced in the skin upon contact with the sun's ultraviolet light.
Formation of Vit D
STEP 1 - The sunlight interacts with a form of cholesterol which is then transferred to the liver or kidneys where it is converted to a form of Vitamin D. This, however, is not the most active form of Vitamin D.
STEP 2 - Another conversion has to take place in the kidneys, before the most active form of Vitamin D - calcitriol, or Vitamin D3 - is achieved.
If you get insufficient exposure to the sun's ultraviolet rays (eg in Winter, foggy periods, if you spend the majority of your time indoors and for people with darkly pigmented skin), production of Vitamin D is reduced. To Download Our Free Vitamin D E-guide Click Here