Study aim: The effects of synbiotic product on gut microbiota changes in patients with multiple sclerosis treated with dimethyl fumarate: A randomized, double-blind, placebo-control clinical trial Design: A Phase 3, randomized controlled parallel-group double-blind clinical trial involving 60 patients will be conducted. Randomization will be implemented utilizing a random block design. Settings and conduct: Patients with MS referred to the MS clinic of Bo Ali Sina Educational Center who meet the inclusion criteria and do not have the exclusion criteria are included in the study and are divided into two groups according to the randomization table and are evaluated for 6 months . The treating doctor, the patient and the evaluator are unaware of the type of therapeutic Participants/Inclusion and exclusion criteria: Adults over 18 years of age with a recent diagnosis of Multiple Sclerosis or a first attack consistent with high-risk primary clinical syndrome based on the McDonald 2017 criteria, disability due to EDSS less than 4.5, and candidates for dimethyl fumarate were included in the study. Also, people who have received systemic antibiotics in the last month, people who have received probiotic supplements in the last 3 month, people who have received omega-3 and antioxidants in the last month, and people who are pregnant and lactating are included are excluded from study. Intervention groups: Familact or placebo capsules daily for 6 months Main outcome variables: Alterations of pathogenic bacteria, Correlation with clinical manifestations of the disease, Adverse effects' profile of immunomodulatory medications