Vitamin D is important risk factor for developing multiple sclerosis (MS) and for disease progression. Patients with MS who had lower vitamin D levels were at increased risk for more clinical attacks and faster disease progression. It was also shown that patients with MS had lower vitamin D levels in serum than healthy controls. It is not clearly defined, which are the levels of vitamin D in serum, that are high enough to trigger immunomodulatory effect and are safe for patients.

This double-blind randomized clinical trial was designed to compare impact of vitamin D supplementation in two different doses (1000 IU/day vs 4000 IU/day) in patients with relapsing remitting MS. The main goal of this trial is to compare dose response on vitamin D supplementation and to estimate more closely appropriate level of vitamin D in serum which triggers some of experimentally shown immunomodulatory actions.

Vitamin D is important risk factor for developing multiple sclerosis (MS) and for disease progression. Patients with MS who had lower vitamin D levels were at increased risk for more clinical attacks and faster disease progression. It was also shown that patients with MS had lower vitamin D levels in serum than healthy controls. It is not clearly defined, which are the levels of vitamin D in serum, that are high enough to trigger immunomodulatory effect and are safe for patients.

This double-blind randomized clinical trial was designed to compare impact of vitamin D supplementation during four months in winter time in two different doses (1000 IU/day vs 4000 IU/day) in patients with relapsing remitting MS. The main goal of this trial is to compare dose response on vitamin D supplementation and estimate more closely appropriate level of vitamin D in serum which triggers some of experimentally shown immunomodulatory actions. To define immunomodulatory response different laboratory, clinical and genetic tests will be performed.

Inclusion Criteria:

• Relapsing remitting MS
• Treatment with immunomodulatory drug
• Age 18-60 years and
• EDSS (Expanded Disability Status Scale) score less than 5.

Exclusion Criteria:

• Use of vitamin D supplements in the past 3 months
• Pregnancy, planning pregnancy or nursing
• Relapse of disease and corticosteroids use in past month
• Active inflammation at the start of the study (flu, cystitis etc.)
• Renal disease
• Elevated levels of calcium or parathormone
• Hypersensitivity to vitamin D preparations
• Switching of immunomodulatory drug in past 3 months
• Other autoimmune disease
• History of hyperparathyroidism, liver disease, tuberculosis, sarcoidosis or kidney stones