The purpose of this work is to investigate the influence of dietary salt intake on immune function in multiple sclerosis (MS) subjects and healthy controls. This study primarily tests the hypothesis that higher dietary salt intake will be associated with a higher frequency of pathogenic Th17 cells and impaired function of protective regulatory T cells. If a relationship between dietary salt intake and immune function is observed, this study will also test: a) whether this relationship is unique to MS subjects or whether it is also present in healthy controls, and b) whether healthier immune function can be restored by restricting dietary salt intake.

The purpose of this work is to investigate the influence of dietary salt intake on immune function in MS subjects and healthy controls. This study primarily tests the hypothesis that higher dietary salt intake will be associated with a higher frequency of pathogenic Th17 cells and impaired function of protective regulatory T cells. If a relationship between dietary salt intake and immune function is observed, this study will also test: a) whether this relationship is unique to MS subjects or whether it is also present in healthy controls, and b) whether healthier immune function can be restored by restricting dietary salt intake. This is a 5-week pilot study of a dietary intervention of 25 subjects with MS or Clinically Isolated Syndrome (CIS) by 2010 Diagnostic Criteria who will be identified and recruited from the Yale MS Center and/or referred from outside MS centers. 25 age-matched healthy controls will be recruited from friends, family members, spouses and the patient waiting room at the Yale MS Center.

Inclusion Criteria:

• Male or Female adult subjects
• Ages 18-60, inclusive
• diagnosis of CIS or MS by 2010 McDonald Criteria (in the case of MS subjects)
• Naive to FDA- approved MS therapies such as glatiramer acetate, interferon-beta, natalizumab, fingolimod, tecfidera, or teriflunomide

Exclusion Criteria:

• Secondary or primary progressive MS
• Prior exposure to FDA-approved MS therapies or chemotherapies of any kind
• Known history of autoimmune disease besides MS
• Known history of renal disease, hypertension or congestive heart failure
• Currently taking medications that could affect urine sodium excretion (e.g. diuretics or others that act on the renin-angiotensins-aldosterone system)