Vitamin D and Why Immunosuppressants May Be Counterproductive

I just saw a post from the Napa County Science News Examiner (thank Google Alerts for that) commenting on an upcoming research paper that will be published in the September issue of "Annals of the New York Academy of Sciences" regarding Vitamin D's role in auto-immune diseases. The post talks about a recent research paper that discusses why Vitamin D may be even more important for women than in men (and could also explain higher rates of auto-immune diseases in women). The paper found that women have a higher number of Vitamin D receptors in their body, in particular in the endometrial cells (lining of the uterus). When Vitamin D binds with these receptors, many genes are expressed that help kick-up the immune system.

Here's an excerpt:

The key to how vitamin D plays its part is to understand what the VDR does. When the correct form of vitamin D (a form known as 1,25-D or calcitriol) binds to VDR, VDR then directly causes the expression of over 900 genes to occur. Two of the genes that are turned on produce proteins that are directly responsible for kicking the immune response into active mode. The reason for VDR in the endometrium is that it provides protection against infection for the developing fetus.

Another key to the puzzle has been the growing evidence that bacteria may play a role in the development of autoimmune disease. If so, why wouldn’t women, who have more VDRs, be better off than men? The problem is that bacteria of various kinds can interfere with VDRs and prevent vitamin D from binding. If vitamin is unable to bind, then the immune response is disrupted. Not only is the immune system affected, but thyroid hormone problems can result too.

There are many clear links that have been established between Crohn's and bacteria. However, this finding could point to why immunosuppressants could be hurting rather than helping the problem. Here's another excerpt:

Although these results do not provide a clear path to treatment, “the potential role of persistent pathogens in autoimmune disease mandates reconsideration of the use of corticosteroids as a first-line treatment for many autoimmune diseases. Corticosteroids effectively reduce the ability of the immune system to respond to pathogens, including persistent microbiota, which is counterproductive to recovery.”

This would suggest that Vitamin D supplementation, particularly in women, is important in recovery. Plus, it really calls into question usage of corticosteroids as a treatment for Crohn's.

With all that said, though, you don't want too much Vitamin D apparently. Another study (from 2004) conducted at UCLA found that people with Crohn's had very high levels of Vitamin D in their blood. The high Vitamin D level (contrary to what you would think) actually causes loss of bone density, which could lead to osteoperosis. Here's the excerpt:

ISLAMABAD: Contrary to expectations, people with the inflammatory bowel condition Crohn’s disease are likely to have excessive levels of the active form of vitamin D in their blood, researchers have found. This is associated with low bone mineral density, they report.

Dr. Maria T. Abreu from the Inflammatory Bowel Disease Center at Cedars-Sinai Medical Center in Los Angeles led the study. She told Reuters Health, "Most doctors think that Crohn’s patients automatically have decreased vitamin D levels and encourage supplementation with vitamin D. We would like to urge doctors to check vitamin D levels before making that recommendation."

As Abreu’s team explains in the medical journal Gut, under certain circumstances too much active vitamin D can actually contribute to the breakdown of bone, leading to osteoporosis. The researchers found "inappropriately high" blood levels of the active form of vitamin D in 42 percent of the 138 people they studied with Crohn’s disease. This was true of only 7 percent of 29 patients with ulcerative colitis, another type of inflammatory bowel disease.

Also, the higher the blood levels of active vitamin D in Crohn’s patients, the lower was their bone density -- regardless of whether they were treated with steroids -- the investigators found. "We believe that high vitamin D levels are most likely a manifestation of the underlying gut inflammation," Abreu said. A high vitamin D level is "an additional risk factor predisposing to development of osteoporosis" for some Crohn’s disease patients, the team concludes. Treatment of the underlying inflammation, "may improve metabolic bone disease."

I suppose it's a mixed verdict then. But at the very least it's worth getting your Vitamin D level checked to see where you are and then only supplement if necessary.