The majority of available literature supports the idea that vitamin D deficiency is a risk factor for the development of MS. This conclusion has resulted in the routine testing of 25(OH)D during the work-up for MS and for those patients who have MS.
The interesting question, according to Patricia K. Coyle, MD, professor in the Department of Neurology at Stony Brook University in New York, is whether vitamin D supplementation can serve as an actual treatment for MS. The idea that vitamin D supplementation can reduce MS disease activity remains controversial. However, a recent study found that patients experiencing their first attack, or clinically isolated syndrome, who had higher blood levels of vitamin D suffered significantly lower levels of disease activity. (Munger KL et al. Ann ClinTransl Neurol. 2014;1:605-617. Ascherio A et al. JAMA Neurol. 2014;7:306-314.)
This result has been a springboard for several studies looking at vitamin D replacement as a strategy for reducing MS disease activity. In addition, many treating neurologists are encouraging their patients with MS with vitamin D deficiency to use supplements, with the goal of higher normal levels (eg, 70 ng/mL).