Inclusion Criteria:  Signed written informed consent. RRMS or PPMS, as defined by the McDonald criteria. Ages 18-65 years. EDSS < 7 Treatment with IFN-beta  Exclusion Criteria:  SPMS without relapses during the past year at screening. Use of high dose systemic steroids within the last 2 months. Gastrointestinal disease, such as inflammatory bowel disease Use of antibiotics within the last 4 weeks.