Microbiome in Multiple Sclerosis​

Over the past 20 years or so a wealth of research has given us a better understanding of the bacterial environment in the human gut. A well-balanced environment is important for “educating” and regulating our immune system. Amongst others, this enables us to fight various infections. It is also important for the body’s ability to manage other conditions or diseases where the immune system plays a role, such as in MS. It is evident that there is a biological link between our gut and the brain. This link is often referred to as the “gut-brain axis”.

The food we eat contains certain fibers that our gut bacteria live off. When the gut bacteria consume and process fibers from our food, they produce certain proteins and fatty acids. These are the substances affecting our immune system. The fatty acids are often referred to as Short Chain Fatty Acids (SCFA).

Studies demonstrate dysbiosis associated with MS, however the exact taxa or species varies from study to study, possibly due to genetic background, geography, food and cultural differences. Functional analysis shows that despite differences in dysbiosis patterns, all studies show a reduction in short-chain fatty acid producing bacteria (Zenga 2019, Takewaki 2020).

This is further supported by studies showing that short chain fatty acids are reduced in the stool and plasma of people with MS. These studies show a consistent pattern of lowered propionate levels in people with MS independent of MS type (Zeng 2019, Duscha 2020, Takewaki 2020, Park 2019, Trend 2021).

The role of propionate in MS

Numerous articles describe how propionate levels are important in maintaining normal levels of T-cell number and activity. In vitro, and in vivo animal data, as well as recent research in patients with MS show that supplemental propionate restores suppressed levels of the anti-inflammatory FoxP3-T-reg cell population and activity and at the same time decreases activity and number of pro-inflammatory Th17 cells (Smith 2013, Park 2015, Haase 2018). This can be considered as a shift of the immune system away from the pro-inflammatory MS state to a normalized state.

A groundbreaking human clinical study, published in Cell 2020, demonstrated that supplementation with 1 g propionate restores T-cell activity towards a normal state as described above. This study was performed on people with both RRMS, SPMS, and PPMS with similar results in each patient cohort. Patients remained on their standard medications and no negative drug interactions were noted. For further details see Duscha et al 2020. This study also confirmed previous findings associating low levels of propionate with increased MS progression and annual relapse rates (Mizuno 2017, Haghikia 2015, Park 2019, Chitrala 2017, Duscha et al 2020). The study is an important milestone in establishing that propionate is a specific nutritional requirement of people with MS. This has been further described in a recent review paper (Tobin 2021).  

For more information see:

Duscha et al 2020: https://pubmed.ncbi.nlm.nih.gov/32160527/

Tobin et al 2021: https://pubmed.ncbi.nlm.nih.gov/34394076/