Deficiency in vitamin D has been widely regarded as contributing to autoimmune disease, but a review appearing in Autoimmunity Reviews explains that low levels of vitamin D in patients with autoimmune disease may be a result rather than a cause of disease and that supplementing with vitamin D may actually exacerbate autoimmune disease.
Authored by a team of researchers at the California-based non-profit Autoimmunity Research Foundation, the paper goes on to point out that molecular biologists have long known that the form of vitamin D derived from food and supplements, 25-hydroxyvitamin D (25-D), is a secosteroid rather than a vitamin. Like corticosteroid medications, vitamin D may provide short-term relief by lowering inflammation but may exacerbate disease symptoms over the long-term.
The insights are based on molecular research showing that 25-D inactivates rather than activates its native receptor - the Vitamin D nuclear receptor or VDR. Once associated solely with calcium metabolism, the VDR is now known to transcribe at least 913 genes and largely control the innate immune response by expressing the bulk of the body's antimicrobial peptides, natural antimicrobials that target bacteria.
Written under the guidance of professor Trevor Marshall of Murdoch University, Western Australia, the paper contends that 25-D's actions must be considered in light of recent research on the Human Microbiome. Such research shows that bacteria are far more pervasive than previously thought – 90% of cells in the body are estimated to be non-human – increasing the likelihood that autoimmune diseases are caused by persistent pathogens, many of which have yet to be named or have their DNA characterized.