Correlation Between Relapses in Multiple Sclerosis (MS) and Vitamin D Intake

Inclusion Criteria: * Inclusion Criteria (MS Group): * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information (PHI) in accordance with national and local subject privacy regulations. * Be age 18 or older at the time of informed consent. * Have a diagnosis of relapsing-remitting multiple sclerosis (RR-MS) as defined by the McDonald Criteria. * Are taking FDA approved immune-modulatory drugs for MS. * Patients had at least one relapse during the year prior to initiation of MS treatment. * After at least 2 years on therapy, patients were classified as MS responders (MS-R) or MS non-responders (MS-NR) based on a clinical criteria recently reported in the literature. A responder (MS-R) is a patient with an annual relapse rate (ARR) \< 0.5 and no evidence of disease progression as measured by EDSS (expanded disability status scale). A hypo/non-responder (MS-NR) is a patient with an ARR \> 0.5 and/or with progression in the EDSS of at least 1 point sustained for 6 months. Inclusion Criteria (Control Group): * Ability to understand the purpose and risks of the study and provide signed and dated informed consent and authorization to use protected health information (PHI) in accordance with national and local subject privacy regulations. * Be age 18 or older at the time of informed consent. * Have not taken any vitamin D supplementation for more than 12 months. Exclusion Criteria: * Exclusion Criteria (MS Group): * Those who have a diagnosis of secondary progressive MS (SPMS) or primary progressive MS (PPMS). * Unwillingness or inability to comply with the requirements of this protocol, including the presence of any condition (physical, mental, or social) that is likely to affect the subject's ability to comply with the study protocol. * Any other condition, clinical finding, or reason that, in the opinion of the Investigator, is determined to be unsuitable for enrollment into this study. * Those who received other forms of treatment under than a FDA approved MS drugs are excluded. Exclusion Criteria(Control Group): * Unwillingness or inability to comply with the requirements of this protocol, including the presence of any condition (physical, mental, or social) that is likely to affect the subject's ability to comply with the study protocol. * History of osteoporosis, kidney disease, parathyroid disease, problems with calcium metabolism, sacrcoidosis, and/or pregnancy. * Current nursing home or bed bound patients. * Any other condition, clinical finding, or reason that, in the opinion of the Investigator, is determined to be unsuitable for enrollment into this study. Inclusion Criteria (Retrospective Chart Review) • Only RR-MS patients who received FDA approved immuno-modulatory drugs for MS. Exclusion Criteria (Retrospective Chart Review) • Patients diagnosed with MS sub-types other than RR-MS.