Patient description: The patient is a 20 year old Caucasian female presents to the clinic with one-sided vision lost and facial weakness, dysarthria and numbness lasting for 1 day. She visited her PCP and underwent brain MRI which revealed a single plaque in the brainstem. After few months, she experienced lower extremities weakness led to balance problem. The second MRI revealed another lesion in the left cerebral hemisphere. The diagnosis of Relapsing Remitting Multiple Sclerosis (RRMS) is confirmed after the second MRI. Her past surgical history is significant for a C-section 2 years ago and she has a one child. She is divorced and is not currently in any sexual relationship. She smokes 10 cigarettes per day and drinks alcohol occasionally. She is working as an editor in a publisher company and she is happy that she can keep working from home most of the time. She is under the treatment of RRMS from 7 months ago.

Clinical trial eligibility criteria: eligible ages (years): 18.0-50.0,  Relapsing Remitting Multiple Sclerosis Must meet Magnetic Resonance Imaging in MS (MAGNIMS) for relapsing-remitting MS Age 18 to 50 years Expanded Disability Status Scale (EDSS) score ≤ 4.0 MS disease duration ≤ 10 years if McDonald Relapse Remitting Multiple Sclerosis (RRMS;) ≤ 1 year if meets RRMS but not McDonald RRMS If the patient meets the McDonald RRMS (rather than McDonald Clinically Isolated Syndrome (CIS) that is now classified as MS) Must have had one clinical attack in past two years and at least one new silent T2 or gadolinium-enhancing lesion on brain MRI within the past year OR Must have had two clinical attacks in past two years, one of which occurred in the past year Females of child-bearing age must be willing to use at least one form of pregnancy prevention throughout the study Must have had a 25-hydroxyvitamin D level of ≥ 15 ng/mL within past 30 days Must be willing to stop taking additional supplemental vitamin D, except as part of a multivitamin, and must be willing to not take cod liver oil  Not be pregnant or nursing No ongoing renal or liver disease No known history of nephrolithiasis, hypercalcemia, sarcoidosis or other serious chronic illness including cancer (other than basal cell or squamous cell carcinoma of the skin), cardiac disease, or HIV No ongoing hyperthyroidism or active infection with Mycobacterium species No known gastrointestinal disease (ulcerative colitis, Crohn's disease, celiac disease/gluten intolerance) or use of medications associated with malabsorption No history of self-reported alcohol or substance abuse in past six months No prior history of treatment with rituximab, any chemotherapeutic agent, or total lymphoid irradiation. No treatment in the past six months with natalizumab, fingolimod, or fumarate. If patient has received glatiramer acetate, they have not been exposed to more than three months of treatment. No treatment with other unapproved therapies for MS No use of interferon beta or glatiramer acetate therapy for one month prior to screening No use of more than 1,000 IU vitamin D3 daily in the three months prior to screening No condition that would limit the likelihood of completing the MRI procedures