What Gut Bacteria Has to Do With MS

They may sound like odd bedfellows, but the bacteria in your gut, known as your microbiome, plays a major role in health and disease.

by Jeanine Barone Health Writer

Not all bacteria are disease causers. In fact, trillions of microbes live in our bodies, usually in a happy state of balance. And none may be more important in human health than the bacteria that live in your gut, known as the gut microbiome. This population of bacteria varies from person to person, and it also varies from day to day, depending on many factors, including the food you eat and medications you take.

Research on the gut microbiome is exploding right now, especially research exploring how an imbalance in the different bacterial populations affect diseases of the nervous system, including multiple sclerosis. “We know as much about the microbiome today as we knew about the genome in the 1970’s, says Sergio E. Baranzini, Ph.D., a professor of neurology at the University of California, San Francisco. “I anticipate we will uncover many surprising ways in which gut bacteria can affect our health in the near future.”

“So much remains to be learned about the manner in which the microbiome and the immune system engage, that it’s too early to conjecture what types of treatments might someday result,” says Erin Longbrake, M.D., Ph.D., an assistant professor of neurology at Yale University in New Haven, CT. “But we do know that the gut microbiome may substantially impact the immune system in multiple diseases, including MS.”

Your Microbiome, Your Health

A brief tutorial: The lining of your gut is full of immune cells and proteins, more than any other part of the body. These act as security guards, protecting your gut from pathogens (disease causers), while also monitoring the good bacteria to make sure you have enough.

Over the years, scientists have found that the gut contains both inflammatory and anti-inflammatory immune cells—both are necessary components to keep your immune system in balance. Inflammation is important for battling invaders, but if it goes awry, it can lead to autoimmune disease like MS where the body attacks its own cells. Likewise, anti-inflammation processes are needed to stop the immune system from going into overdrive.

Bacteria in the gut manufacture enzymes that can activate certain types of immune cells. Some of these bacteria can activate a pro-inflammatory immune response, and others stimulate an anti-inflammatory response. An imbalance in these bacteria is believed to play a role in an array of conditions, from cancer to diabetes, as well as numerous neurological diseases, such as Parkinson’s, Alzheimer’s, and MS. With MS, scientists believe that this imbalance in gut bacteria contributes to a dysfunctional immune system that chronically attacks its own tissues.

The MS Gut Microbiome Is Different

At least according to some studies, people with MS have a different array of bacteria in different amounts in their gut microbiome compared with healthy people. Overall, they have less of the type of bacteria that stimulate an anti-inflammatory response, and more that cause a pro-inflammatory response by the immune system. The result: Bolder inflammatory reactions that may contribute to the progression of the disease.

According to Dr. Longbrake, “The changes in the gut microbiome seen in MS are subtle. There isn’t a single bacterium that’s moved in and is causing disease; rather, the relative amounts of many normal types of gut bacteria shift around.”

Interestingly, researchers are now finding that treating people who have MS with disease-modifying therapies (DMTs) alters their microbiome to look more like one found in healthy people, suggesting that the gut bacteria in people with MS may indeed play a role in the disease. Hoping to identify what, exactly, that MS-related gut bacteria is, the International MS Microbiome Study is collecting data from people around the world who have never been on, or are no longer taking, medication.

Zeroing In on Gut Bacteria

It turns out, people with MS have an abundance of two particular sorts of bacteria (Aciinetobacter and Akkermansia) in their gut that are rare among healthy people, according to a study published last year by scientists at the University of California, San Francisco. In the lab, when researchers mixed these gut bacteria with blood from healthy people, the bacteria activated specific immune cells that promote an immune attack while decreasing the kind of immune cells that suppress the immune system from going overboard. But even more interesting, one of the bacterial types seen in the people with MS has a molecular resemblance to proteins found in the myelin sheath, a coating that covers the body’s nerves. This matters because it’s the myelin that comes under attack during MS flares, making researchers wonder if the microbes in the gut could be the trigger for these attacks.

More evidence of the gut bacteria and MS link comes from the Max Planck Institute of Neurobiology in Germany, where investigators looked at almost three dozen sets of twins in which only one person had MS. When the twins’ gut microbes were transplanted into healthy lab rodents, it was the bacteria from those with MS that were much more closely linked with the animals getting an MS-like disorder compared with the bacteria from the healthy twin.

Can a Fecal Transplant Treat MS?

Inspired by findings like those at the Max Planck Institute, other researchers are exploring whether transplanting feces (along with the bacteria it contains) from a healthy person could rebalance the gut microbiome in someone with MS so that there’s a greater amount of the anti-inflammatory bacteria and less of the bad, pro-inflammatory kind.

There are serious risks with this treatment, since transplanting stool from someone can result in a serious infection in the person receiving the transplant. Nonetheless, scientists are now conducting clinical trials among people with Relapsing-Remitting MS [RRMS] to determine if a fecal transplant can be done safely and provide benefits. “Clinical trials are being conducted, one at UCSF, to evaluate the safety of this procedure in MS,” says Dr. Baranzini. “The next step is to test for efficacy.”

How Diet Affects the Microbiome

Another approach to modifying gut bacteria in someone with MS may be through diet itself. Meals rich in animal fat, red meat, salt, sugar, and fried foods are seen as a risk factor for MS, largely because they increase inflammation in the body. These foods also contribute to an imbalance of bacteria in the gut microbiome, resulting in an immune response that’s pro-inflammatory.

“While a potential link with diet has always been hypothesized, we are now closer than ever to identify the relationship between nutrients and gut microbes to encourage rational diet design,” says Dr. Baranzini.

On the other hand, a diet centered on fruits, vegetables, and legumes, as well as fish with omega-3 fatty acids (fish oils), helps rebalance the gut’s microbiome and stimulates metabolic pathways that are anti-inflammatory. It’s no wonder scientists are becoming increasingly interested in how a healthy, balanced diet might affect the gut microbiome in a way that counteracts the inflammation seen in MS, and perhaps even protect against the disease.

Can Taking A Probiotic Supplement Help?

Even within a healthy diet, certain foods could ply a bigger role than others in balancing your gut microbiome. Probiotics refer to foods (such as yogurt) and supplements containing beneficial bacteria. While it sounds like a promising path to improving gut health, the effect of probiotics on the immune system is complex. After all, some bacteria are anti-inflammatory, while others are proinflammatory, which theoretically could make things worse in the case of MS.

Many probiotic studies are small and poorly controlled, so meaningful results are hard to come by. Nonetheless, researchers are hopeful that learning more about how probiotics might balance the gut microbiome could be beneficial to people with MS.

So what should you take away from this latest research? Well, if you have MS, it’s possible new treatments in the near future may address your gut as much as they do your brain. But much more work needs to be done to determine the exact microbes that contribute to MS and how exactly the contribute to the destructive effects of the disease.

In the meantime, your best bet is to eat a balanced diet, rich in plant foods along with fish while also maintaining a healthy body weight. It’s a can’t-hurt plan, that just could help.

  • Gut Microbiome in MS (1): Science Reports. (2016). “Multiple sclerosis patients have a distinct gut microbiota compared to healthy controls.” ncbi.nlm.nih.gov/pubmed/27346372
  • Gut Microbiome in MS (2): Cell Transplantation. (2019). “The Gut Microbiota in Multiple Sclerosis: An Overview of Clinical Trials.” journals.sagepub.com/doi/full/10.1177/0963689719873890
  • Immune System and Gut Microbiome in MS (1): Brain. (2019). “Gut microbiota-dependent CCR9+CD4+ T cells are altered in secondary progressive multiple sclerosis.” ncbi.nlm.nih.gov/pubmed/30770703
  • Immune System and Gut Microbiome in MS (2): Science Advances. (2017). “High frequency of intestinal TH17 cells correlates with microbiota alterations and disease activity in multiple sclerosis.” ncbi.nlm.nih.gov/pubmed/28706993
  • Immune System and Gut Microbiome in MS (3): Annals of Neurology. (2018). “A probiotic modulates the microbiome and immunity in multiple sclerosis.” ncbi.nlm.nih.gov/pubmed/29679417
Jeanine Barone
Meet Our Writer
Jeanine Barone

Jeanine Barone is a scientist and journalist with an eclectic background. She’s a nutritionist and exercise physiologist who regularly writes about travel, health, fitness, and food for numerous top-tier publications. Jeanine enjoys active travel, especially long-distance cycling and cross-country skiing.