Vitamin D Information:

There is the convention of referring to 2 types of Vitamin D , Vitamin D2 and Vitamin D3. In humans, Vitamin D3 (cholecalciferol) is converted from it's basic building block (cholesterol) when ultraviolet light hits Pro-Vitamin D (a squalene metabolite) in the cells of our skin. Vitamin D3 does not have significant biological activity, rather, must be metabolized, first by the liver and then by the kidneys into the converted, fully-active, hormonal form of Vitamin D (calcitrol). In plants, Vitamin D2 (ergocalciferol) is converted from it's basic building block (ergosterol) when ultraviolet light from the sun hits the leaves of the plant. Though frequently referred to as Vitamin D2, ergocalciferol is NOT really Vitamin D, but rather a Vitamin D analog. It was a patented drug before the patent ran out. It does not occur in humans, is only half as potent as cholecalciferol, has been associated with most of the Vitamin D toxitity cases, and should be avoided. Vitamin D (cholecalciferol) is a pre-hormone that has long been known for its important role in regulating body levels of calcium and phosphorus, and in mineralization of bone. Vitamin D is metabolized into a potent steroid hormone called calcitriol. More recently, it has become clear that receptors for calcitriol, are present in a wide variety of cells, and that calcitriol, has biologic effects which extend far beyond control of mineral metabolism. It is believed that vitamin D and its metabolites, play an important part in the regulation of genes involved in cell growth, differentiation and proliferation. By promoting differentiation and inhibiting proliferation, vitamin D may become an important factor in cancer prevention and therapy.