There are two basic forms of vitamin D.
The first is Ergosterol and is the vitamin D found in plants.
The second is Cholesterol and is the vitamin D in humans.
Vitamin D2 is produced by the sun shining on a plant leaf causing the ergosterol to turn into ergocalciferol – or – vitamin D2
In a similar fashion, when our skin is exposed to the suns ultraviolet rays 7-dehydrocholesterol (a type of cholesterol) produces vitamin D3.
Vitamin D2 does not fully meet our needs so it must be further metabolized by our bodies. These conversions take place in two steps, the first requires a specific enzyme and production in the liver, skin, kidney and a few other places.
The second step of the conversion takes place in the liver, lung, brain and other places of our body with a different unique enzyme to produce the final Dihydroxyvitamin D that humans require. It is the only hormone type of vitamin D that is fully active and it needs to be replenished on a habitual basis.
What is Vitamin D?
Over the past decade or so the perception of vitamin D has changed. It turns out that Vitamin D isn’t just a simple fat soluble vitamin it was once thought to be and is actually a hormone important in bone growth and mineral metabolism.
Simply explained a vitamins job is to regulate our metabolism so it functions well. And vitamin D does do this. it helps in our muscle and immune functions, assists in bone development and insulin and calcium.
And in the same fashion as with cortisol and estrogen, our bodies have vitamin D receptors (VDR’s) on the cell membranes of most types of cells. This way vitamin D has an important function to promote the absorption of calcium though the intestine. Without adequate vitamin D calcium cannot be properly absorbed.
Vitamin D deficiency
One of the most common side-effects of vitamin D deficiency is Rickets, which causes bone deformities. Another disease is osteomalacia. The history of Cod Liver Oil as a vitamin D supplement goes back hundreds of years and has been historically effective in maintaining healthy vitamin D levels in the human body.
Commonly people who live in the northern hemisphere and subject to lack of natural sunlight are at risk of lack of vitamin D. However a twist to lack of sunlight is in areas that have abundant sunlight persons who’s dress is to cover their bodies completely and to be heavily veiled are also are at risk.
Persons who don’t venture into the sunlight along with the invention of sun-blocker with high SPF ratings put people at risk of vitamin D deficiency as well.
In some cases a person my have a genetic defect in their VDR, and others with liver or kidney disease; that can interfere with their ability to produce Dihydroxyvitamin D.
In these cases vitamin D supplement may be recommended.