Low levels of vitamin D in patients with autoimmune disease may be a result rather than a cause of the disease, and supplementing with this nutrient may worsen a patient's condition, according to a review.
Researchers at the California-based non-profit Autoimmunity Research Foundation, who have authored the review, say that vitamin D may provide short-term relief by lowering inflammation, but it may exacerbate disease symptoms over the long-term.
Written under the guidance of professor Trevor Marshall of Murdoch University, Western Australia, the paper mainly focuses on the actions of a form of vitamin D derived from food and supplements, known as 25-hydroxyvitamin D (25-D).
The researchers say that 25-D inactivates rather than activates its native receptor, the Vitamin D nuclear receptor (VDR), and subsequently the immune response.
They say that this, though lowers the inflammation caused by bacteria, allows them to spread more easily in the long-run.
According to them, low levels of 25-D are frequently noted in patients with autoimmune disease because they are naturally down-regulated in response to VDR dysregulation by chronic pathogens.
Under such circumstances, supplementation with extra vitamin D may not only be counterproductive but harmful also, because it slows the ability of the immune system to deal with such bacteria.
"Vitamin D is currently being recommended at historically unprecedented doses. Yet at the same time, the rate of nearly every autoimmune disease continues to escalate," points out Amy Proal, one of the paper's co-authors
A research article on this study has been published in Autoimmunity Reviews.