A diet rich in vegetables and low in protein reduced inflammation in multiple sclerosis (MS) patients by modulating the gut microbiome and promoting bacteria that helps control a hyper-reactive immune system.

The study reporting the findings, “Immunological and Clinical Effect of Diet Modulation of the Gut Microbiome in Multiple Sclerosis Patients: A Pilot Study,” was published in the journal Frontiers in Immunology.

An increasing amount of data supports the idea that changes to the natural flora of microorganisms within the gut, known as the gut microbiome, plays a role in MS.

As antibiotics are known to alter the microbiome composition, so does diet, and both can change the interaction between the microbiome and the immune system. For example, one study with the established mouse model for MS – the so-called experimental autoimmune encephalomyelitis (EAE) mice – showed that a low-calorie diet had a beneficial effect in EAE, while a salt-rich diet increased disease severity by increasing the activity of immune cells called Th17 cells.

Now, a team of researchers tested the hypothesis that MS disease activity can be affected by dietary patterns.

The team conducted a small pilot study with relapsing-remitting multiple sclerosis (RRMS) patients attending the Multiple Sclerosis Rehabilitation Unit of the Don Carlo Gnocchi Foundation in Milan, Italy.

Researches analyzed the participants’ gut microbiome together with additional clinical parameters, including their immune system, at the time of recruitment. They then compared the results after patients had followed two different diets – a Western diet (WD) and a high vegetable/low-protein diet (HV/LP) – for at least one year.

The WD was characterized by the “regular consumption of red meat, processed meat, refined grains, sweetened food, salt, and an overall high intake of saturated and omega-6 fatty acids,” the researchers wrote.

In total, 20 patients participated in the study and they were equally divided: 10 in the Western diet group and 10 in the HV/LP group.

The microbiome of patients changed in a diet-specific manner: Those fed with a HV/LP diet saw their microbiome enriched in Lachnospiraceae bacteria and showed a decrease in their pro-inflammatory profile.

Lachnospiraceae bacteria produce a compound called butyrate, which has been suggested to promote immunotolerance while reducing inflammation.

Also, “in the HV/LP diet group alone, the relapse rate during the 12 months follow-up period and the Expanded Disability Status Scale score at the end of the study period were significantly reduced,” the team wrote.

In contrast, patients fed a Western diet were seen to have an increase in bacteria belonging to the phylum Euryarchaeota, previously shown to be associated with shorter time to disease relapse in pediatric MS patients.

Overall, these results “support the possibility that diet could possibly be used as a tool to modulate the immune system in an anti-inflammatory way as a consequence of changes in the gut microbiota,” the team concluded.

“It will be important to replicate these results in ampler cohorts of MS patients and to expand these observations in inflammatory diseases other than MS,” researchers added.