It has long been known that vitamin D plays a vital part in maintaining strong bones and teeth. There is new evidence that vitamin D has a crucial role in regulating your immune functions, according to a 2009 paper in “Expert Reviews in Clinical Immunology.” The review adds that vitamin D deficiency may be linked to many diseases. Vitamin D is also needed to boost white blood cell production.
Your Immune System
Your immune system protects you from a plethora of intruding viruses, bacteria and parasites and a host of other disease-causing organisms. The immune system has two lines of defense, or attack. The first is non-specific and includes your skin, tears, the hair in your nostrils and the mucus in your respiratory system, to name a few. The specific defense system are your white blood cells that come in two basic types – lymphocytes, from your lymph system, and leukocytes, or white blood cells.
White Blood Cells and Vitamin D
White blood cells carry a vitamin D receptor that allows the immune system to guard against infection. There are several different types of WBCs, including dendritic cells and macrophages, each requiring vitamin D to perform their jobs. The Linus Pauling Institute states that in specific cases, macrophages may produce an enzyme that is needed to make the active form of vitamin D to enable the macrophages to function properly.
In the event of vitamin D deficiency, the antimicrobial peptide cathelicidin is low. Cathelicidin is produced by WBCs to attack microbial invaders. Vitamin D promotes increased production of this broad spectrum peptide and increases your immunity to infection. Without vitamin D, as in the case of a deficiency, you are more open to disease and illnesses. A 2008 study in the "Journal of Allergy and Clinical Immunology" supplemented 14 subjects with 4,000 international units of vitamin D daily over three weeks and found that the white blood cells produced more cathelicidin.
Link Between Vitamin D and White Blood Cells
New physiological functions of vitamin D are emerging, claims the article in “Expert Reviews in Clinical Immunology.” It is becoming apparent that vitamin D insufficiency and deficiency are linked to poor immune functioning, which may translate to low white blood cell counts. The review adds that vitamin D deficiency is associated with increased infections and susceptibility to cancer, but more research is necessary. Do not replace vitamin D supplementation for any traditional medication or treatment without consulting your doctor.