Vitamin D is a fat soluble organic substance and belongs to the group of both vitamins and hormones.
It is found in some foods, but its main absorption is by sunlight.
It is also available in formulations as a dietary supplement. After its intake, it is first metabolised
to the liver and then to the kidneys, through a process called hydroxylation.

Vit D main functions are to regulate the absorption of calcium by the intestine and maintain a sufficient amount of calcium and phosphorus, for proper bone growth and health. Therefore, vit D role is evident of the proper functioning of the musculoskeletal system.
Recent studies have shown that vitamin D also plays an important role in normal function of the immune system. This was shown by the presence of its receptors not only in the musculoskeletal cells, but also in a group of cells of the immune system.
Thus, it regulates innate and acquired immunity and helps by balancing the immune system and preventing of chronic inflammations, various cancers and autoimmune diseases.
Vitamin D TOTAL deficiency is defined as the condition that 25 (OH) D is <20 ng / ml
vitamin D PARTIAL deficiency when 25 (OH) D levels are between 21–29 ng / ml.

As mentioned above, after its intake, Vitamin D is metabolised in the liver, on its main metabolite.
called 25-hydroxyvitamin D3 [25 (OH) D3]. Then, 25 (OH) D3 is metabolized to active 1,25-dihydroxyvitamin D3.

It is now known that immune cells have also the mechanism needed to convert 25 (OH) D3 into 1.25 (OH) 2D3.
1,25 (OH) 2D3 has significant immunomodulatory activity in addition to its bone metabolism.

Vitamin D and immune system

When the immune system is activated, its T and B cells as the other reaction mechanisms begin to work faster, resulting in localised inflammation.
We know that Vitamin D has an inhibitory effect on immune cell behaviour, thereby limiting inflammation.
Thus, total or partial deficiency of vitamin D can lead to an increase in the incidence of autoimmune diseases.
Multiple sclerosis, type 1 diabetes. the systemic lupus erythematosus, IBS, Thyroid dysfunction or Arthritis, can be some of them.

People with autoimmune problems are advised to monitor and correct vitamin D levels as a first step in treating the problem, as studies show that vitamin D3 has the potential to help both prevent and treat these conditions.
Our observations and studies have establish a strong relation between the vitamin D levels and the imbalance of the immune system.
We have also found that by improving the condition and the balance of the immune system, the vitamin D levels can balance nicely without the need for the addition of extra vitamin D.