Primary endpoint: To determine the effects of vitamin D supplementation at two doses a) 5,000 IU daily b) 10,000 IU daily compared to c) placebo a 24 weeks period on the change from baseline in frequency of CD4 T cell subsets and cytokine responses by peripheral blood mononuclear cells in 1) patients with the clinically isolated syndrome. 2) healthy control participants.
Secondary endpoints:
1. To determine whether there is a dose response effect of supplementation using 5,000 IU and 10,000 IU of vitamin D versus placebo over 24 weeks on the change from baseline in the frequency of CD4 T cell subsets and cytokine responses by PBMC in 1) patients with the clinically isolated syndrome (CIS) 2) healthy control participants
2. To establish whether there is a clinical response to vitamin D measured by a) change in the number of T2 lesions and Gadolinium enhancing lesions on MRI scanning at 24 weeks compared to baseline b) reduction in relapses over 24 weeks in treated (both 5,000 IU and 10,000 IU) CIS patients versus CIS patients receiving placebo.
