While scientists have long known that vitamin D plays a critical role in bone health, recent research has begun to suggest that it also serves to regulate the immune system, helping prevent infection, cancer and autoimmune disorders. Until now, the mechanism by which the vitamin acts on the immune system has been unknown.
In a study published in the journal Nature Immunology, researchers from the University of Copenhagen found that when a variety of white blood cells known as a T-cell comes across a pathogen in the bloodstream, it extends a receptor in search of vitamin D. If it encounters the vitamin, the T cell becomes “activated.” If there is not enough vitamin D in the blood, the cell remains passive and no immune response occurs.
The body produces vitamin D upon exposure to sunlight. It can also be found in eggs, fatty fish, fortified milk and in supplement form.
Once activated, a T-cell transforms into one of two kinds of cells. One type seeks out and destroys all traces of the infectious agent, while the other records information about the pathogen and transmits it to other parts of the immune system. These latter (“helper”) cells help the immune system respond quickly should infection with a similar pathogen occur at a later date.
In addition to providing new information about the importance of vitamin D, the study provides hope for better understanding — and perhaps prevention — of the unhelpful immune responses that result in autoimmune disorders like allergies or Type 1 diabetes, as well as those that cause the body to reject transplanted organs. The researchers were able to determine what chemical steps occur to transform a T-cell from active to inactive, suggesting the possibility that doctors may eventually be able to initiate or block this process, depending on the patient’s need.