Vitamin D

It is one of the fat soluble vitamins 

It may surprise you that (Vitamin D) is not a vitamin as it is known.

It's actually a hormone !

Its main function is the absorption of calcium  and phosphorus  in the intestine

But how do we get it?

There are two sources of vitamin D:

1- Nutritional

Here we have three options:

1- Natural food 

2- Nutritional Supplements 

3- Fortified foods 

Here, vitamin D is in natural food or supplements in D2 or D3 form.

2- Metabolism

The formation of vitamin D by the sun's rays falling on the skin's surface, then it is formed.

It goes through several initial stages:

It starts as (Dehydrocholesterol-7) in the skin, and when exposed to the sun, it turns into (pre-vitamin D3) and then into (Vitamin D3).

Here we have vitamin D3 from both sources

This is the primitive (inactive) form of vitamin D, which goes through further stages of transformation until reaching the final build.

In the first stage, vitamin D3 is absorbed through circulation and becomes

(Vit D DBP)

(Vitamin D Binding Protein)

After that, it moves to the liver for the following manufacturing process

Where the process of (hydroxylation) is updated to turn into

(25-hydroxyvitamin D3)

Then it goes to the kidneys for the last industrial process.

A second (hydroxylation) reaction takes place to convert to (1,25 dihydroxyvitamin D3) the active form, which is called

[Calcitriol]

Here, it can perform its three main functions:

1- Maintaining the efficiency of immune cells

2- Bone mineralization

3- Calcium and phosphorous absorption in the intestine

To learn about natural food sources of vitamin D, click here

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