Vitamin D is well understood to be vital in bone formulation and maintaining bodily calcium homeostasis. A growing body of research indicates a definite link role for vitamin D in autoimmunity prevention as well. This simple supplement may be key in preventing and treating autoimmune diseases.
Understanding Vitamin D
Vitamin D is a fat-soluble vitamin that plays a role in both calcium homeostasis and overall bone health. Vitamin D promotes calcium absorption in the gut, maintaining adequate calcium and phosphate concentrations. Without sufficient levels of vitamin D, bones can become brittle, thin, or misshapen. Diseases such as rickets and osteomalacia are the result of vitamin D deficiency. Vitamin D-related calcium deficiencies can also lead to hypocalcemic tetany which causes cramps and spasming due to involuntary muscle contraction.
In addition to modulating cell and bone growth and initiating bone remodeling, vitamin D also takes part in the reduction of inflammation, metabolizing glucose, and modulating neuromuscular function and the immune system. The role of vitamin D in autoimmunity is still under scrutiny and is further explored below.
Vitamin D is produced endogenously in human cells when the skin is exposed to UV radiation, particularly from sunlight. Vitamin D can also be consumed, and is naturally present in some foods, though some people (especially those who do not live in very sunny climates) require dietary supplements to bring their vitamin D levels to viable values.
What is Autoimmunity?
Autoimmunity occurs when the body mistakes its own tissues or organs for harmful intruders. The immune system sends out its defenses to attack itself. Autoimmunity arises in many forms, including rheumatoid arthritis, Crohn’s disease, and multiple sclerosis. Type 1 diabetes is a common autoimmune disease in which the immune system destroys the cells in the pancreas that produce insulin.
While the symptoms of immunity are dependent on its form, common examples include tissue damage, inflammation, and loss of functionality in compromised organs. Incidents of autoimmunity seem to be on the rise among Western countries, but emerging research indicates that introducing greater levels of vitamin D in autoimmunity cases may be an effective treatment method.
Increasing Vitamin D in Autoimmunity Treatment
Vitamin D deficiency has a clear association with many conditions and diseases, including poor bone health, cardiovascular disease, and even cancer. In fact, before the discovery of antibiotics, mycobacterial infections such as tuberculosis used to be treated with vitamin D. A continuously growing body of research indicates that vitamin D deficiency also plays a role in autoimmune diseases.
In a study published in 2017, “Vitamin D in Autoimmunity: Molecular Mechanisms and Therapeutic Potential,” authors Dankers, et al. examine the role of vitamin D in autoimmunity’s progression. Working with the understanding that vitamin D deficiency is common in patients suffering from autoimmunity, the study examined the mechanism of vitamin D in the immune response.
How It Works
Vitamin D exists in the body in an inactive precursor form: 25(OH)D3. Before it can perform its role in the immune response, 25(OH)D3 must be converted into its active vitamin D form. This conversion, previously thought to be conducted only in the liver, can be completed by many different immune cells, including macrophages, monocytes, B cells, T cells, and dendritic cells. Conversion of inactive 25(OH)D3 to active vitamin D by immune cells allows the concentration of vitamin D to be regulated locally at the site of inflammation.
Blood lymphocytes display receptors for active vitamin D which allow the vitamin to influence the body’s immune response. Nearly all immune cells express this receptor, making them prone to modulation mediated by active vitamin D. Initial binding to the receptor—a nuclear receptor—initiates a signaling cascade. If levels of active vitamin D are low, calcium in the body must be mobilized from the bone rather than from the intestines.
The Conclusion of Dankers, et al.
While active vitamin D is best known for its role in facilitating calcium absorption into the intestine and thus maintaining calcium homeostasis, research continues to indicate that the vitamin has a larger part to play. Because immune cells are involved in the local activation of vitamin D and vitamin D receptors are found on all immune cells, the vitamin clearly has an important role in the work of the immune system.
Dankers, et al. consider the available literature evidence sufficient to advocate for vitamin D supplementation to be included in the treatment and prevention of autoimmune diseases such as type 1 diabetes, Crohn’s disease, rheumatoid arthritis, multiple sclerosis, and systemic lupus erythematosus.