Multiple Sclerosis (MS), Serotonin & Gut Microbiota

An interesting November 2017 review1 looks at the relationship between multiple sclerosis (MS) and what happens in our GI tract – the microbiota (bacteria and other microbes) that form an essential part of the microbiota-gut-brain axis.

The statements they make are quite definitive about how important the health of our intestinal “friends” – those trillions of bacteria that represent more than 10 times the number of human cells within a human) – are to the potential prevention/treatment of MS. And, of course, if you believe the adage that “we are what we eat“, then it will be no surprise to you that the type of gut bacteria that live inside us will be determined to a large extent by the foods we eat.

The authors of this review point out that the underlying signalling mechanisms involved in the interaction between gut microbiota and those who develop MS have not been fully explored as yet; although there appears to be little question that this interaction exists.

They look at evidence that supports the fact that the microbial-modulated neurotransmitter serotonin (specifically 5-hydroxytryptamine (5-HT)), being regulated by the gut microbiome, is a potent candidate as a mediator of the gut-brain axis in demyelinating disorders such as MS. (Demyelinating diseases involve the immune system attacking the myelin sheath or the cells that produce and maintain it. This causes inflammation and injury to the sheath and ultimately to the nerve fibres that it surrounds.)

They conclude that: “Our comprehensive overview of literature provides evidence that 5-HT [serotonin] levels in the gut are controlled by the microbiome, both via secretion and through regulation of metabolites. In addition, we demonstrate that the gut microbiome can influence the formation of the serotonergic system (SS) in the brain [serotonergic denotes a nerve ending that releases and is stimulated by serotonin.] We also show that SS alterations have been related to MS directly-altered expression of 5-HT transporters in central nervous system (CNS) and indirectly-beneficial effects of 5-HT modulating drugs on the course of the disease and higher prevalence of depression in patients with MS.

Joe’s comment

For those suffering from or worried about contracting MS, it seems pretty safe and sensible to look at the research data related to the role of diet. I have written two previous articles that might help as starting points for your research: Multiple Sclerosis & Saturated Fat and Multiple Sclerosis and Diet.


  1. Serotonin: A mediator of the gut-brain axis in multiple sclerosis. Malinova TS, Dijkstra CD, de Vries HE. Mult Scler. 2017 Nov 1:1352458517739975. doi: 10.1177/1352458517739975. PMID: 29117778. []