Is supplemental vitamin D useful in the clinically isolated syndrome (CIS) typical of multiple sclerosis?

The race/ethnicity of participants is not given d-Lay MS and should be included in future studies of vitamin D supplementation in CIS. It will be of interest to investigate the long-term effects of supplementation, initially given in CIS, on the disease and physical activity associated with the progression to RRMS. Interferon beta and teriflunomide are effective in CIS, and due to their different mechanisms of action to vitamin D, may have additive effects with the supplement. As vitamin D supplementation is associated with low or no adverse effects, this supplementation should be considered further in clinical trial and in real life treatment of CIS.