Research from Swedish scientists using experimental models has suggested that immune activation as a consequence of increased intestinal permeability may play a fundamental role in multiple sclerosis. While we can’t directly control our immune system, emerging research suggests we may be able to support healthy immune function by focusing on gut health. Intestinal permeability may place ongoing demands on the immune system, which may be particularly relevant for those navigating autoimmune conditions where the immune system is already working overtime.
Many researchers have focused on the gut-autoimmune connection and have found some promising results. Over the last decade, research on MS has expanded beyond pharmaceutical approaches to include gut health and the role it may play not only in the development of MS but in supporting overall wellness. Several studies have identified gut dysbiosis—an imbalance of bacteria in the digestive tract—as a potential factor in MS development, something researchers wouldn’t have considered just 10 years ago.
If you’ve been told that medications are the only approach or find it hard to believe the gut has anything to do with neurological conditions, this article explores what the research actually shows.
Understanding Multiple Sclerosis: The Basics
Multiple sclerosis (MS) is a chronic neurological condition that affects the central nervous system, including the brain and spinal cord. MS is also classified as an autoimmune disease—in all autoimmune conditions, the body produces antibodies that can attack its own tissues.
In people with MS, this autoimmune process targets the outer protective covering of nerves called the myelin sheath. The myelin sheath supports effective communication between the central nervous system and the rest of the body. When myelin is damaged, it may cause altered or impaired basic body functions, potentially affecting everything from mobility to vision.
According to the Atlas of MS third edition published in 2020, approximately 2.8 million people worldwide are living with MS (35.9 per 100,000 population). This represents an increase from earlier estimates of 2.5 million, with MS prevalence rising in every world region since 2013. The pooled incidence rate suggests someone in the world is diagnosed with MS approximately every 5 minutes.
People of Northern European descent have the highest risk of developing MS, and globally, females are twice as likely to have MS as males. However, this ratio varies significantly by country—in some regions, the ratio of women to men is as high as 4:1. People with MS are most commonly diagnosed between the ages of 20 and 50, and early recognition is often considered optimal for management.
No single test or symptom is sufficient for an MS diagnosis. Rather, healthcare providers use a series of strategies including thorough medical history review, neurological exams (balance and coordination tests), and MRI imaging to detect disease-related changes in the brain or spinal cord. Cerebrospinal fluid analysis may also be used.
Ruling out other conditions is an important part of accurate diagnosis given the complexity of MS. Blood testing helps rule out conditions known to cause similar symptoms, including Lyme disease, B12 deficiency, and thyroid dysfunction.
How MS Develops: The Role of T-Cells and Immune Response
Researchers generally agree that MS involves an inflammatory process of the central nervous system (CNS) that occurs as a result of an abnormal immune response. T-cells are a specific type of white blood cell integral to immune function. Under normal circumstances, they help protect and defend against potential threats.
In those with MS, T-cells may attack various components of the CNS and contribute to inflammation that can lead to structural changes. In people with MS, the immune system targets the myelin sheath, and when this protective covering is damaged (called demyelination), communication between the brain and the rest of the body may be slowed or impaired.
Pro-inflammatory Th1 and Th17 lymphocytes are considered pivotal in MS pathophysiology, highlighting an imbalanced interaction with regulatory T cells (Tregs). T-cells may not only affect myelin but can also release chemicals that impact nerve fibers (axons) and potentially recruit additional immune cells to sites of inflammation.
Researchers continue to study what allows T-cells to be activated in this way and have found that both environmental factors and genetics appear to play a role. A genetic predisposition has been identified in many autoimmune conditions, including celiac disease, rheumatoid arthritis, and psoriasis—and MS is no exception.
Changes to the HLA-DRB1*15:01 allele provide the strongest genetic association with MS development. The HLA-DRB1 gene belongs to the human leukocyte antigen (HLA) complex, which helps the immune system distinguish the body’s own proteins from those made by foreign invaders. Each gene within the HLA complex plays a role in immune function, allowing the immune system to respond to a wide variety of unfamiliar proteins.
The Gut-Brain Axis: A Two-Way Communication System
The gut-brain axis (GBA) refers to the bidirectional communication between the intestinal system and the nervous system. This complex network involves interactions between the endocrine, immune, autonomic, and enteric nervous systems, connecting brain activity and gut functions.
It’s nearly impossible to view the gut and the immune system as two separate entities—approximately 70% of our immune system resides within or around the gut wall. The gut is protected by an immunoglobulin called Secretory IgA (SIgA), which can be thought of as a protective layer that helps shield us from potential threats.
The gut microbiota affects many aspects of brain development and function, including:
- Microglia and astrocyte maturation and polarization
- Blood-brain barrier (BBB) formation and permeability
- Neurogenesis
- Myelination
This means disruption of the gut-brain axis may participate in the pathophysiology of several brain conditions, including MS.
The Leaky Gut Connection: Intestinal Permeability and MS
Research has begun examining the relationship between intestinal permeability (often called “leaky gut”) and MS. A 2017 pilot study demonstrated that people with relapsing-remitting MS are more likely to have compromised intestinal permeability compared to healthy controls.
What Is Intestinal Permeability?
The gut lining serves as a selective barrier, allowing nutrients through while keeping larger molecules and potential threats out. This barrier function is maintained by proteins called tight junctions—including occludin, claudin, and zonulin-1—that regulate what passes between intestinal cells.
When these tight junctions become compromised, the intestinal barrier may become more permeable than intended, potentially allowing substances to pass through that normally wouldn’t.
Zonulin: The Connection Between Gut and Brain Barriers
Zonulin is a protein produced by the small intestine that regulates tight junction assembly. Research has shown that zonulin blood levels are elevated in people with MS. What’s particularly interesting is that zonulin may affect not just the intestinal barrier but potentially the blood-brain barrier as well.
A 2020 study found that zonulin concentrations were significantly higher in MS patients when MRI confirmed active blood-brain barrier disruption. Zonulin levels were also associated with 1-year disease progression in progressive MS.
This research suggests that zonulin may mediate breakdown of both the intestinal barrier and the BBB through regulation of tight junctions—potentially explaining how the gut-brain axis may modulate neuroinflammation in MS.
The Fasano Autoimmunity Theory
Dr. Alessio Fasano’s groundbreaking research on intestinal permeability and autoimmune conditions proposed that three factors must exist together for autoimmune conditions to develop:
- A genetic predisposition to autoimmunity
- An environmental trigger
- Increased intestinal permeability
This theory suggests that addressing intestinal permeability may be relevant for supporting those navigating autoimmune conditions.
Gut Dysbiosis in Multiple Sclerosis: What the Research Shows
Numerous studies have reported altered gut microbiota composition in people with MS compared to healthy controls. This microbial imbalance, termed dysbiosis, has been identified as a potential factor in MS-related processes.
Key Findings on MS and Gut Bacteria
Research has revealed several consistent patterns in MS-associated dysbiosis:
Decreased beneficial bacteria: Studies show MS patients often have reduced levels of Faecalibacterium, a genus known for producing beneficial metabolites. A 2016 study found MS patients had decreased amounts of anti-inflammatory microbes Erysipelotrichaceae and Veillonellaceae compared to healthy controls. Both are members of the Firmicute family—Veillonellaceae have been shown to support regulatory T-cell function, while Erysipelotrichaceae have anti-inflammatory properties.
Altered microbial metabolites: Research has found decreased Butyricimonas in the gut microbiome of MS patients. This is significant because Butyricimonas produces butyrate, a short-chain fatty acid with important functions we’ll explore below.
Fecal transplant studies: Twin studies have shown that transferring feces from an MS-affected twin to germ-free mice induced more severe experimental autoimmune encephalomyelitis (EAE) symptoms than feces from the healthy twin, suggesting specific gut bacteria may influence disease processes.
As researcher Sachiko Miyake noted in the PLOS peer-reviewed scientific journal: “Correcting the dysbiosis and altered gut microbiota might deserve consideration as a potential strategy for the prevention and treatment of MS.”
Note: This quote reflects the researcher’s hypothesis and should not be interpreted as medical advice. Always consult with healthcare providers about MS management.
The Microbiome’s Secret Weapon: Short-Chain Fatty Acids and Butyrate
One of the most exciting areas of MS-gut research involves short-chain fatty acids (SCFAs)—metabolites produced when gut bacteria ferment dietary fiber. The three main SCFAs are acetate, propionate, and butyrate, each with distinct functions.
What Are Short-Chain Fatty Acids?
SCFAs are the most abundant metabolites produced by colonic bacterial fermentation of indigestible carbohydrates. Roughly 95% of SCFAs are absorbed by colonocytes (cells lining the colon) where they:
- Serve as an energy source for intestinal cells
- Help maintain barrier integrity by regulating tight junction expression
- Support mucus production
- May be transported to the bloodstream to exert systemic effects
SCFAs and Immune Modulation
SCFAs have important immunomodulatory properties mediated by:
- Inhibition of histone deacetylase (HDAC)
- Activation of G protein-coupled receptors (GPRs) on immune cells
These mechanisms may help explain how gut-derived metabolites could influence immune function throughout the body.
Butyrate: The Myelin Connection
Butyrate has emerged as particularly interesting in MS research. A 2019 study published in the Journal of Neuroinflammation revealed that treatment with butyrate:
- Suppressed demyelination in experimental models
- Enhanced remyelination in association with facilitating oligodendrocyte (myelin-producing cell) differentiation
The researchers concluded: “Our findings shed light on a novel mechanism of interaction between the metabolites of gut microbiota and the CNS and may provide a strategy to control demyelination and remyelination.”
Additional research has shown that:
- Preventive administration of butyrate provided beneficial effects on CNS autoimmunity in animal models
- Butyrate-treated mice showed significantly improved myelinated areas compared to controls
- Butyrate significantly suppressed demyelination and enhanced remyelination in organotypic slice cultures
- Administration of methyl butyrate reduced effector T cells in the CNS and intestinal lamina propria while increasing regulatory T cells and IL-10 secretion
Butyrate’s Mechanisms of Action
Butyrate interacts with G protein-coupled receptors (GPCRs), primarily GPR41 and GPR109A, triggering various intracellular pathways involved in immune modulation. The regulation of GPR109A by butyrate may indirectly support regulatory T cell expression and IL-10 secretion.
Additionally, butyrate acts as an HDAC inhibitor on oligodendrocytes, potentially supporting remyelination processes. At the blood-brain barrier level, butyrate may activate AMPK, which in turn may support tight junction assembly.
Propionate: Clinical Evidence
A landmark 2020 study published in Cell investigated propionic acid supplementation in MS patients:
- Serum and feces of MS subjects showed significantly reduced propionate amounts compared to controls, particularly after the first relapse
- After 2 weeks of propionate intake, researchers observed a significant increase in regulatory T cells while Th1 and Th17 cells decreased
- Post-hoc analyses revealed reduced annual relapse rate, disability stabilization, and reduced brain atrophy after 3 years of propionate intake
A 2024 review confirmed that propionate supplementation may help support regulatory T cell function, and long-term supplementary therapy was associated with clinical improvements in study participants.
How Fiber Feeds Beneficial Bacteria
The bacteria that produce these beneficial SCFAs require fuel—primarily dietary fiber. When you consume fiber-rich foods, gut bacteria ferment these indigestible carbohydrates and produce SCFAs as byproducts.
Foods that promote the growth of beneficial bacteria include:
- Fruits and vegetables rich in pectin, cellulose, and inulin
- Whole grains containing resistant starch
- Legumes with prebiotic oligosaccharides
These microbiota-accessible carbohydrates are fermented by gut bacteria to produce SCFAs, linking diet directly to the regulation of the bacterial ecosystem’s composition.
Probiotics and MS: What Research Suggests
Given the connection between gut bacteria and MS, researchers have explored whether probiotic supplementation might offer benefits.
Probiotic Research Findings
A study examining probiotic supplementation in MS patients found that:
- Probiotic administration increased the abundance of taxa known to be depleted in MS, including Lactobacillus
- Probiotic use decreased the abundance of taxa previously associated with dysbiosis in MS, including Akkermansia and Blautia
- At the immune level, probiotic administration was associated with an anti-inflammatory peripheral immune response characterized by decreased frequency of inflammatory monocytes
Experimental research found that mice given an oral mixture of probiotic Lactobacillus species showed effects associated with regulatory T-cell activity and a reduction in inflammatory cell numbers.
Recent Clinical Findings
A 2025 study published in eBioMedicine connected microbial tryptophan metabolites to specific changes in MS patients’ immune systems after probiotic intervention, supporting the hypothesis that probiotics containing lactobacilli might support healthy immune regulation through increased SCFA or tryptophan metabolite production.
Supportive Strategies: A Gut-Focused Approach
While MS management should always be guided by healthcare providers, research suggests several gut-supportive strategies that may complement conventional approaches:
1. Prioritize Fiber-Rich Foods
Since short-chain fatty acids are produced from dietary fiber, ensuring adequate fiber intake may help support SCFA production:
- Aim for a variety of vegetables, fruits, whole grains, and legumes
- Consider prebiotic-rich foods like onions, garlic, leeks, asparagus, and Jerusalem artichokes
- Gradually increase fiber intake to allow gut bacteria to adapt
2. Consider Fermented Foods
Fermented foods naturally contain beneficial bacteria and may support microbiome diversity:
- Yogurt with live active cultures
- Kefir
- Sauerkraut and kimchi
- Kombucha
3. Support Gut Barrier Function
Some individuals choose to support gut barrier function with targeted nutrients:
- L-glutamine has been studied for its potential to support intestinal mucosa by supporting gut barrier function
- Zinc carnosine may support stomach and intestinal lining health
- Omega-3 fatty acids may support healthy inflammatory response
4. Address Potential Triggers
Research suggests certain factors may negatively impact gut barrier function:
- Chronic stress may affect gut barrier integrity
- Certain medications (particularly long-term NSAID use) may impact intestinal permeability
- Highly processed diets may not provide optimal fuel for beneficial bacteria
5. Work With Healthcare Providers
Any gut-supportive protocol should be discussed with your healthcare team, especially when navigating a complex condition like MS. Consider working with practitioners who understand the gut-immune connection.
The Bottom Line
The research connecting gut health and multiple sclerosis continues to evolve, but the evidence increasingly suggests that what happens in the gut doesn’t stay in the gut. From intestinal permeability affecting blood-brain barrier function, to gut bacteria producing metabolites that may influence myelination, the gut-brain axis appears relevant to understanding MS.
Key takeaways from the research:
- Intestinal permeability markers are elevated in MS patients, particularly during active disease phases
- Gut dysbiosis is consistently observed in MS, with reductions in beneficial SCFA-producing bacteria
- Short-chain fatty acids, particularly butyrate and propionate, show promising effects on immune regulation and myelination in research settings
- Probiotic supplementation may support beneficial changes in gut bacteria composition and immune markers
- Diet plays a role in shaping the gut microbiome and SCFA production
While we can’t claim these strategies treat, cure, or prevent MS, supporting gut health represents an area where individuals may have some agency in their wellness journey. As researcher Carlos Camara-Lemarroy noted, understanding how the gut-brain axis modulates neuroinflammation in MS could open new therapeutic possibilities.
The connection between gut health and MS reminds us that our bodies function as integrated systems. Supporting one area—like gut health—may have far-reaching effects throughout the body.
Frequently Asked Questions
Can leaky gut cause multiple sclerosis?
Research hasn’t established that leaky gut directly causes MS. However, studies show that people with MS often have altered intestinal permeability markers, and Dr. Fasano’s research suggests intestinal permeability may be one factor among genetics and environmental triggers in autoimmune development. The relationship appears complex and bidirectional.
What is the gut-brain axis and why does it matter for MS?
The gut-brain axis is the two-way communication system between your digestive tract and nervous system. Research shows gut bacteria can affect blood-brain barrier permeability, immune cell development, and even myelination—all relevant to MS. This connection may explain how gut health could influence neurological conditions.
What are short-chain fatty acids and how might they help with MS?
Short-chain fatty acids (SCFAs) like butyrate and propionate are produced when gut bacteria ferment dietary fiber. Research suggests these metabolites may support regulatory T cell function and healthy myelination. MS patients often show reduced SCFA-producing bacteria, and supplementation studies have shown promising immune-modulating effects.
Should people with MS take probiotics?
Some research suggests probiotic supplementation may support beneficial changes in gut bacteria and immune markers in MS patients. However, probiotic effects can vary based on strains and individual factors. Discuss probiotic supplementation with your healthcare provider, who can help determine if it’s appropriate for your situation.
What foods support gut health for people with MS?
Research suggests high-fiber foods support SCFA-producing bacteria. Fruits, vegetables, whole grains, and legumes provide the fermentable carbohydrates gut bacteria need to produce beneficial metabolites. Fermented foods may also support microbiome diversity. The Mediterranean diet pattern has been associated with beneficial outcomes in some MS research.
How long does it take to improve gut health?
Gut bacteria composition can begin shifting within days of dietary changes, though meaningful microbiome changes typically develop over weeks to months. Studies on SCFA supplementation have shown immune marker changes within 2 weeks, though clinical effects may take longer to observe. Consistency in gut-supportive practices is key.
Can fixing leaky gut reverse MS?
No supplement or dietary approach has been shown to reverse MS. However, Dr. Fasano’s research suggests that addressing intestinal permeability may be relevant for supporting those with autoimmune conditions. Supporting gut health should be viewed as one component of comprehensive wellness, not a replacement for medical care.
What’s the connection between zonulin and MS?
Zonulin is a protein that regulates tight junctions in both the gut and blood-brain barrier. Studies show elevated zonulin in MS patients, particularly during active disease. This suggests zonulin may be involved in both intestinal permeability and BBB disruption, potentially explaining how gut dysfunction could affect the CNS.
Key Takeaways
- An estimated 2.8 million people worldwide are living with MS, with prevalence increasing in every world region
- Research consistently shows gut dysbiosis in MS patients, with reduced beneficial bacteria that produce short-chain fatty acids
- Intestinal permeability markers, particularly zonulin, are elevated in people with MS and correlate with disease activity
- Butyrate and propionate show promising effects on immune regulation and myelination support in research settings
- The gut-brain axis provides a communication pathway that may explain how gut health influences neurological function
- Fiber-rich diets support the production of beneficial short-chain fatty acids by gut bacteria
- Supporting gut health represents an area where individuals may complement their medical care
Medical Disclaimer
This content is for informational and educational purposes only and is not intended to be a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified healthcare provider with any questions you may have regarding a medical condition or before starting any new supplement, diet, or wellness program.
The statements made on this website have not been evaluated by the Food and Drug Administration. Our products and the information provided are not intended to diagnose, treat, cure, or prevent any disease.
Individual results may vary. Do not disregard professional medical advice or delay seeking it because of something you have read on this website.