What is Vit D ?

What is Vitamin D?

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.

Through its regulation of genes, calcitriol controls the production of immune factors known as lymphokines, which effect cell-mediated immunity functions.

Vitamin D may play a role in the prevention and/or treatment of the following health conditions:


Atherosclerosis
Heart Disease
Hypertension
Breast cancer
Colon cancer
Prostate cancer
Skin cancer
Kidney disease
Liver disease
Multiple sclerosis
Muscle Weakness
Chronic Pain
Osteoporosis
Osteoarthritis
Periodontal disease
Preeclampsia
Psoriasis
Tinnitus
Mental Illness
Depression
Epilepsy
Diabetes
Obesity
Ulcerative colitis
Inflammatory bowel disease

Vitamin D is NOT actually a Vitamin.

Contrary to common belief, Vitamin D is NOT actually a vitamin at all. "Vitamins" by definition, are nutrients that CANNOT be produced by the body, but are NECESSARY for the proper functioning of the body's tissues and organs. Although Vitamin D is ESSENTAL for calcium and phosphorus metabolism, and IS required for the normal development of healthy bones and teeth, since it IS produced by our bodies (when our skin is exposed to ultraviolet rays from the sun) technically, it can NOT be considered a vitamin.

Vitamin D was originally classified as a vitamin because of the findings of a British researcher in 1920, who raised dogs in the winter (without any exposure to sunlight or ultraviolet rays). He found that the animals developed rickets (a bone disease) unless fed a diet containing fish-liver oils. He wrongly concluded that the fat soluble substance needed for developing bones was not found naturally in the body and so was a "vitamin". In 1924 researchers discovered that exposing skin to sunlight resulted in the body's own production of this so-called "fat-soluble vitamin". Despite the misnomer, for nutritional and public health reasons, vitamin D continues to be officially classified as a "vitamin".

There are two basic types of vitamin D . . .
Or are there ?

If one sifts through the published studies and literature about Vitamin D, one will see many inconsistencies and contradictions which lead to much confusion on the subject. As mentioned above, referring to Vitamin D as a vitamin in the first place is a misnomer. If that weren't confusing enough, there is also the convention of referring to 2 types of Vitamin D . . .
Vitamin D2 and Vitamin D3.

1. 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).

2. 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.


The IOM (Institute of Medicine) of the National Academy has not established an RDA (Recommended Dietary Allowances) for Vitamin D, only an AI (Adequate Intake) for otherwise healthy persons to avoid metabolic bone disease. Although the current AI for Vitamin D is around 200 iu/day recent research suggests 5,000 iu/day of cholecalciferol is optimum for those who do not have regular, year-round sun exposure.

Other researchers including Robert Barefoot have suggested doses as high as 30,000 iu/day.


It is very important to note that Vitamin D should NOT be taken by anyone who has primary hyperparathyroidism, sarcoidosis, granulomatous disease, or other conditions that cause high blood calcium.