Multiple sclerosis is a pro-inflammatory demyelinating disease of the central nervous system. The etiology of MS is complex and poorly understood. Both genetic and environmental factors play a role and recent evidence suggests that gut microbiota is one of the key environmental factors. Gut microbiota is increasingly being seen an important environmental risk factor for multiple sclerosis, and strategies to correct an imbalance in intestinal flora.The first study, "Multiple sclerosis patients have a distinct gut microbiota compared to healthy controls," published in Scientific Reports, found that people with relapsing-remitting MS have altered fecal microbiota and may have microbial dysbiosis. People with MS had reduced levels of a protein called aryl hydrocarbon receptor circulating in their blood.Aryl hydrocarbon receptor is involved in many biological processes, including inflammation. The researchers found that gut microbiota play a role in turning tryptophan, and amino acid found in food, into Aryl hydrocarbon receptor agonists, which act on cells of the nervous system called astrocytes and limit inflammation of the central nervous system. Low levels of Aryl hydrocarbon receptor in multiple sclerosis patients may explain how microbial dysbiosis could be causing the condition.Increased constipation and fecal incontinence and increased gut permeability in multiple sclerosis patients, and increased occurrence of inflammatory bowel diseases in MS patients and their families suggest an important gut-central nevus system connection.Interestingly, gut bacteria can also influence the blood brain barrier integrity. These studiesimplicate that gut microbiota may potentially be operational in predisposition to or modification of the disease course of multiple sclerosis.