Vitamin D, Part 2

While the role of a low vitamin D level is a becoming an established risk factor for MS, it is not universally accepted as such.  Even less clear is the role for vitamin D supplementation once the diagnosis of MS has been made is less clear.  A study published in the journal Neurology in 2010 studied a total of 49 patients over a one-year period.  Of these, 25 received high doses of oral vitamin D while 24 subjects, known as the control subjects, received no additional vitamin D supplementation.  These doses used in the study were quite large with subjects increasing their intake of vitamin D to up to 40,000 units per day.  The trial was an open-label trial, meaning that both the evaluating doctors and the subjects in the study knew if they were getting the vitamin D or not. 

Open-label trials are far from conclusive in showing a treatment effect.  Nonetheless, the results of the study were intriguing.  Based on this study I am confident that high doses of vitamin D are safe in patients with MS.  However, the study also suggested a treatment effect in patients with MS.  The patients who received the high doses of vitamin D had their relapse rate cut by 41% compared with those who did not.   Additionally, about double the percentage of patients receiving the high dose of vitamin D had no relapses at all compared with the control subjects. 

This study had several limitations, which the authors themselves readily pointed out.  First of all, the findings have to be replicated in a properly controlled study.  This means conducting a larger study with more patients, ideally over a longer period of time.  Moreover, any proper study of vitamin D in MS would have to be “blinded.”  This means that neither the study investigators nor the subjects participating in the trial know whether they are being treated with high doses of vitamin D or placebo.  Such trials are enormous undertakings and can be usually be carried out by drug companies with large budgets.  So it is possible that such a trial with vitamin D will never be done.

So what is the upshot of these findings?  Patients with MS should probably take vitamin D supplements and they should be confident that this is a safe and inexpensive treatment for MS, even at high doses.  The efficacy of this treatment at this time is only suggested, however, and while it may be helpful in treating relapses, further studies will need to be done to firmly establish this.  Additionally, vitamin D taken through supplements might function differently than vitamin D produced naturally via sunlight exposure. Indeed, one recent student found that in an animal model of MS, exposure to ultraviolet light, not vitamin D levels, seemed to have impact on the disease. So I also tell my patients to try to get at least some direct sunlight exposure every day. I do caution them to put sunscreen on their face, and would not make this recommendation in anyone with a history of skin cancer or a strong family history of skin cancer.  Clearly further research is needed to clarify the role of vitamin D in developing MS and the treatment of the illness.