This will be an open-label prospective study design with respect to MS immunomodulatory therapy choice. Study group will be defined as subjects with a relapsing form of multiple sclerosis as defined by the McDonald criteria choosing to begin dimethyl fumarate (DMF) therapy. Blinding of the principal investigator and study subject to microbiota analysis results will be maintained until the planned end of study. Subjects who receive at least one dose of DMF and subsequently discontinue therapy will be invited to complete the study on alternative immunomodulatory therapy or no therapy. Data from subjects who have received at least one dose of DMF and who withdraw early from the study will be included in analysis as last visit carried forward. A goal has been set to enroll 25 subjects for this study.