Cholecalciferol is an inactive hormone made in our skin when it is exposed to ultraviolet B light. It is created using cholesterol. Another name for cholecalciferol is Vitamin D3. It is the most potent precursor to the active vitamin d called calcitriol. Calcitriol is created in our liver. Cholecalciferol is transformed into active Vitamin D.
Vitamin D was recognized as essential to bone growth many years ago. Without enough, a disease called Rickets develops and the bones of children become soft and deformed. A minimum standard was recommended based on the amount needed to prevent Rickets.
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There is a growing body of evidence that Vitamin D3 is a controller or influencer in many other vital body functions. The amount that is needed is also much higher than the minimum amount needed to prevent Rickets.
Immunity is reduced or hampered if Vitamin D3 levels are low in our body. During the Swine Flu problem, many experts recommend 5000 or more international units of Vitamin D3 per day to help boost the immune system. It is thought that the cough and cold season may in part be due to lack of adequate sun exposure during the winter months. Supplementing with Vitamin D3 should help boost immunity and resistance to many common viruses.
Bacterial Vaginosis, a common bacterial infection in women, has been linked to insufficient Vitamin D3 levels in the blood. Other more serious problems that are connected to inadequate Vitamin D are breast and colon cancer. The darker the skin the greater the risk. It takes 30% longer for a person of color to produce Vitamin D from the sun as it does someone who is Caucasian. This may account for the higher rates of breast and skin cancer in people with darker skin.
There is a concept called cognitive reserve. It explains why some peoples' brains have the physical changes of Alzheimer's disease but none of the symptoms. Those without the extra connections and without healthy brain tissue are more likely to suffer the symptoms earlier. Vitamin D plays an important role in the creation of and integration of new brain cells.
When you take a Vitamin D3 supplement be sure it is cholecalciferol and not ergocalciferol. The ergo-type is made from irradiated yeast and is at least 30% less bioavailable when compared to cholecalciferol. Because Vitamin D is often extracted from Cod livers, it frequently contains high levels of Vitamin A. Vitamin A is in its active form and can be active in our bodies also. Too much can be toxic but just a little less than toxic is harmful to the health of our bones, especially our spine. Post-menopausal women should avoid extra Vitamin A completely for this reason.
Check the label be sure it says cholecalciferol and that it has no vitamin A or that it was made from sheep lanolin. Hairy mammals like sheep can make vitamin D in their hair. Sheep also have a fat in their hair called lanolin. Vitamin D3 can be extracted from the lanolin and the label will say made from lanolin on it. Mine does!