Immune system and vitamin D

Immune system and vitamin D

Vitamin D is produced by the body in response to sunlight as a by-product of a chemical reaction that occurs when UV light hits the skin. It also occurs naturally in foods like fatty fish, fish liver oil and egg yolk.  

Unfortunately, half of adults in developed countries have a deficiency of vitamin D. The symptoms of vitamin D deficiency can be vague and can include tiredness and general aches and pains. Some people may not have any symptoms at all. If you have a severe vitamin D deficiency you may have pain in your bones and weakness; you may also have frequent infections.

The low level of vitamin D is linked to bone fragility, cancer or heart disease. What is more, vitamin D deficiency has been also associated with numerous autoimmune diseases (celiac, Hashimoto’s, diabetes). Vitamin D plays an important role in balancing the Th1 (cell-mediated) and Th2 (humoral) arms of the immune system. It does this by influencing T-regulatory (Th3) cells, which govern the expression and differentiation of Th1 and Th2 cells.

Vitamin D has also another little-known role: it regulates insulin sensitivity and secretion and balances blood sugar. A recent study showed that vitamin D deficiency is associated with insulin resistance. Insulin resistance and dysglycemia adversely affect thyroid physiology.

Body functions depending on vitamin D

  • Immune system, fighting infection
  • Muscle function
  • Cardiovascular function, healthy heart and circulation
  • Respiratory system, healthy lungs
  • Brain development
  • Anti-cancer effects

Commonly, variable levels of vitamin D across population are thought to be a simple matter of exposure: failure to get enough sun, not eating enough fatty fish or lack of supplements.

What not everybody knows is that the vitamin D performs its functions after activating the vitamin D receptor (VDR). The problem is that many people with autoimmune disease have a genetic polymorphism (DNA sequence variations) that affects the expression and activation of the VDR and thus reduces the biologic activity of vitamin D. Studies have shown that a significant number of patients with autoimmune Hashimoto’s disease have VDR polymorphisms. Low thyroid hormones require steady doses of vitamin D3.

Activated vitamin D has two main functions

  • Manages calcium in your blood, bones and gut
  • Helps cells all over your body to communicate properly

Another concern for people with celiac (thus limited absorption processes) is that their digestive tract cannot adequately absorb vitamin D from food.

Unfortunately, it seems that there is no universal guideline regarding the right dose of vitamin D. Both, too little and too much of it can strongly affect your well-being. My vitamin D level is measured regularly together with the level of the thyroid hormones by my doctor. I am using a D-cura supplement dose 25000IE once in two weeks.

Overall, doctors and researchers are still working to fully understand how vitamin D works within our body and how it affects our overall health.


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