New emerging evidence suggests that the early stages of an autoimmune disease may actually be caused by the breakdown of the body’s gut barrier rather than genetic issues. This growing understanding highlights why gut health has become a central focus in autoimmune disease research. Once the intestinal wall has become too porous, which is referred to by scientists as increased intestinal permeability (leaky gut syndrome), the digestive tract allows undigested food particles, bacteria, and toxins to pass directly into the bloodstream. This triggers an immune response to the presence of these unwanted visitors. In those predisposed to developing autoimmune diseases due to their genes, the immune system may mistakenly attack the body’s own tissues through a process known as molecular mimicry. While other factors could also contribute to triggering autoimmune diseases, the gut may be one of the earliest and most modifiable sites at which to intervene.
Key Takeaways
Priya has been keeping a record of lab tests for many months now that have all returned as normal. There were days when she would sleep through most of the afternoon. She had pain in her joints (her hands) at the end of each week prior to deadlines. Rashes appeared on her skin every time there was an exam period; they completely disappeared once the exams were finished. Her labs were good. Her thyroid levels were normal. Her doctor said the same thing others say, “it’s probably just stress.”
It wasn’t nothing. It also wasn’t “just” stress.
And although this is a story about people without easy access to high-tech testing, I believe this is just as much a story about anyone, anywhere. In July of 2026, longevity investor Bryan Johnson shared information about himself. Mr. Johnson spent tens of millions of dollars tracking virtually every measurable part of his biological self. He was told he had developed an autoimmunity to his stomach lining (autoimmune gastritis). His only indication that there were problems with his health over ten years ago would have been low ferritin (a measure of iron levels).
Even someone like Bryan Johnson, who tracks almost everything that goes into measuring the health of his body, did not catch the problem.
Doctors worldwide are starting to see what their patients in India and elsewhere have been telling them for some time: A large number of the new cases they are seeing with unexplained, overlapping symptom patterns are related to something that the standard diagnostic panels never check – whether or not your gastrointestinal lining is healthy. If your GI lining starts breaking down, you could potentially develop inflammation due to an overreaction by your immune system, and that inflammation could be turned inward against you. To start addressing this issue before we make a diagnosis, we need to understand how the breakdown in the integrity of your GI lining leads to this type of problem.
The primary role of the immune system is to recognize what is “self” versus what is “non-self”, and then respond appropriately by attacking only “non-self”. For example, bacteria, viruses, and damaged cells are identified and attacked. However, the immune system should leave healthy self-tissue alone.
However, when an individual has an autoimmune condition, the body’s immune system fails to make the appropriate distinction. The immune system generates antibodies against the body’s own cells, called autoantibodies, and begins attacking healthy tissue as though it were a foreign threat. This may manifest differently depending on where in the body the self-cells being targeted reside. For example, it may cause joint inflammation in Rheumatoid Arthritis, thyroid function problems in Hashimoto’s disease, or it may result in widespread systemic symptoms for individuals suffering from Lupus. It is now estimated that there are greater than 80 different types of autoimmune disorders, which affect approximately 5 to 8 percent of the world’s population. Women experience autoimmune diseases at a much higher rate than men.
While the genetic component loads the “gun” that fires the first shot that leads to an autoimmune condition, researchers have been unable to identify why the number of new cases of autoimmune disorders has increased so dramatically over the last several decades based solely on genetics. Therefore, researchers believe that some sort of external factor is firing the second shot that results in an autoimmune condition, and increasingly, researchers are looking at the gut as one of the places to find it.
In India, autoimmune diseases were very uncommon.
Today they are growing at an alarming rate. Doctors all over India have reported an increasing number of patients with various types of autoimmune disease, such as thyroid problems, rheumatoid arthritis, lupus, and Psoriasis.
Between 2015-16 and 2020-21, the National Family Health Survey (NFHS) reported that the proportion of Indian women with a thyroid problem had risen by nearly 33%, from 2.2% to 2.9%. Rheumatoid Arthritis is three times more common in cities than it is in rural India, according to a study conducted in 2024.
While it may seem like just another “tube” for your body to absorb the nutrients you need for digestion, your intestines contain many layers of cells that act as a checkpoint to decide what will be absorbed into your bloodstream & what will be blocked off. These cells are held together with structures called Tight Junctions, which act like adjustable seals. In a normal functioning gut, these seals allow the absorption of nutrients, water & smaller molecules to enter your blood while keeping larger indigestible pieces of food, bacteria & toxins on the outside of your body.
The checkpoints in your gut also serve as an immune training location for your body’s immune system. Approximately 70% of all immune cells reside in and surrounding areas of your gut. These cells continuously sample everything passing through the barriers and learn to differentiate harmless substances from actual pathogens. As long as your barriers remain intact, this process occurs silently. However, problems arise once the integrity of the seal itself becomes compromised, at which time gut health ceases to be a digestive function and begins to be an immune function.
Increased intestinal permeability (also referred to as the “gut barrier” being “leaky”) occurs when tight junctions, which join cells in the wall of the intestine, become too loose. As a result of this, substances such as bacterial products, undigested proteins, toxins, etc., can enter the bloodstream, which may lead to various conditions including immune system dysfunction and/or the development of an autoimmune condition. This mechanism underscores why the connection between leaky gut and autoimmune disease is far more significant than standard diagnostic panels typically account for.”
Alessio Fasano, an immunologist at Harvard Medical School, has demonstrated that zonulin is one of the most important regulatory proteins responsible for controlling the degree to which the tight junctions of the gut wall remain open or closed. He also demonstrated that zonulin overexpression leads to the onset of autoimmune diseases in genetically predisposed individuals. Various factors contribute to the opening of tight junctions, such as long-term exposure to chronic stress; use of certain antibiotics; consumption of a large amount of processed foods; and, in some people, gluten.
It should be noted that, although there is no doubt regarding the mechanisms involved in opening up tight junctions of the gut wall with resulting increased intestinal permeability, direct-to-consumer marketed commercial blood and stool zonulin testing has been proven to be inaccurate and therefore it is recommended that a consumer obtain a comprehensive gut and inflammatory panel rather than a single marker test kit.
When the gut barrier gets disrupted, foreign invaders make their way into the bloodstream. The immune system will then fight off whatever it finds foreign; however, some of the items invading the blood have shapes (antigens) that are very close to those of antigens already on our bodies.
As a result of this similarity, when immune cells identify something with an antigen that they’ve previously identified as foreign, instead of fighting off just the invader, they’ll go after everything else that has the antigen. This phenomenon is referred to by scientists as “molecular mimicry,” and is recognized as one of the most clear examples of how changes in gut permeability lead to autoimmune diseases.
Therefore, individuals who experience disruptions to their gut barriers will likely present themselves differently depending upon where in their body the misidentification of antigens occurs. In various forms, molecular mimicry has been linked to conditions such as Celiac Disease, Type I Diabetes, and Rheumatoid Arthritis.
When we talk about how our gut works, we have to think beyond the barrier itself. There are over 1 trillion organisms, all working together with us, and this collective group of organisms is called the gut microbiome. If this collection becomes unbalanced, then a condition referred to as dysbiosis exists.
At this point, the beneficial bacteria that generally provide an environment for the mucus layer and tight junctions to function properly will be reduced. Conversely, some less desirable or “less friendly” microorganisms may expand their presence.
There are consequences related to the immune system as well. Microorganisms play a role in regulating the balance between Th17 (inflammatory) cells and T-regulatory cells (cells that act as regulators of the immune response). Dysbiosis disrupts that balance, tilting the system toward chronic, low-grade inflammation.
The process creates a self-reinforcing loop: a weakened barrier allows more bacterial products into circulation, which continues to upset the balance of the microbiota, which weakens the barrier once again. This is why gut microbiome composition, not barrier integrity alone, has become a central focus in autoimmune research, particularly in conditions like lupus and rheumatoid arthritis.
You may have a genetic predisposition to developing autoimmunity; however, you cannot alter this aspect of your risk. In addition, while genetics alone often does not give us the complete picture as to why an individual develops an autoimmune disease, there are many elements that contribute to the deterioration of gut barrier function and overall health that are within your power to change.
Your diet quality, the number of antibiotics you use, the amount of chronic stress you experience each day, and your sleep habits can all impact your gut lining’s ability to maintain integrity over time. Following a personalized gut health diet plan, where appropriate, may help support a healthier gut environment alongside other lifestyle changes. While none of these will provide a 100% protective effect from autoimmune diseases by themselves, they do represent the aspects of your equation that were previously considered non-modifiable and now offer opportunities for you to intervene.
The majority of standard Blood Tests do not measure the gut barrier function and/or the microbiome balance, although this article has described both as potential Early Modifiable Autoimmune Risk Factors. This knowledge may be valuable regardless of whether there is a plan to have testing done.
Longeny’s truGut360 assessment evaluates the patient’s Microbial Diversity, Dysbiosis Patterns, and Inflammation Markers, providing an overall view of gut health that many standard check-ups cannot provide. For individuals looking for a comprehensive gut microbiome test in India, this clinically interpreted assessment offers a broader evaluation than single-marker consumer tests. For those patients who would like to address their specific gut barrier or dysbiosis results, Longeny has developed a 90 Day Gut Repair Plan focused specifically on addressing these issues.
As previously noted, because many of the single-marker consumer test kits have significant inaccuracies, having a Clinically-Interpreted Broader Panel is usually a better method of determining what is really occurring in the gut.
Priya’s journey did not conclude when she received her diagnosis. Her journey concluded when she could clearly see how her fatigue and joint issues were directly related to an existing leaky gut barrier issue that was compromised long before anyone would check for it. The most significant distinction is usually not in finding a solution to fix everything at once, but in realizing you know where to begin.
If anything I’ve described thus far has resonated or felt similar to you, the initial reaction shouldn’t be fear or panic. The next action should be gathering knowledge. When you understand your gut barrier/microbiome status, you will have clarity regarding which areas need to be addressed in order to begin resolving your symptoms.
Leaky gut or increased intestinal permeability does not itself cause autoimmune disease. However, for genetically predisposed people, it may be one of many possible “triggers” (as with other food sensitivities) because substances allowed through the leaky gut wall will stimulate an immune reaction against them, potentially causing some part of the immune system to target the body’s own tissues.
Molecular mimicry occurs when something external to the body, like a bacterium’s protein or gliadin found in wheat or barley, has a similar shape to something that is found inside the body, e.g., a protein on your white blood cells. The body’s immune system may confuse these two things and continue to attack healthy tissue even if the foreign substance has been removed from the body.
While a person’s gut health is never going to solely decide whether they develop an autoimmune disorder, there is growing recognition of both impaired gut barriers and abnormal microbial flora as additional environmental contributors to developing an autoimmune condition.
Physicians believe this rise in autoimmune disorders is due to stress of modern city life (urbanization), poor air quality, changes in diet, and use of antibiotics. The National Family Health Survey (NFHS) reports that the rate at which thyroid disorders were reported by women in India went from 2.2 percent in 2015-2016 to 2.9 percent in 2020-2021.
Yes. Bacteria living within the gastrointestinal tract assist with maintaining an equilibrium between pro-inflammatory and anti-inflammatory immune cells. A disruption to that equilibrium (dysbiosis) will compromise the integrity of the gut barrier allowing for increased inflammation associated with autoimmune conditions.
There have been studies linking the dysfunction of the gut barrier and rheumatoid arthritis and lupus, with research showing that intestinal permeability may be one of several environmental triggers that could lead to disease activity in individuals who are genetically predisposed.
It usually occurs when you have a combination of your genetics or heredity making you susceptible to the development of an autoimmune condition and some type of environmental insult, such as damage to your gut wall, causing your immune system to mistakenly identify good cells as bad cells.
Increased intestinal permeability causes loose connections between the gut lining cells, thus allowing bacteria and/or undigested food products to pass into the bloodstream. This may lead to an immune response against the body’s own cellular material if these substances mimic or appear similar to the body’s own cellular material due to “molecular mimicry”.
Tight junctions are structural components that maintain contact between intestinal lining cells; at the same time, they regulate how much is allowed to pass from the lumen into the bloodstream. Increased intestinal permeability indicates that there has been a loss of functional tightness, thereby impairing the gut lining’s ability to filter selectively.
Dysbiosis of the gut microbiota disrupts the relationship between inflammatory (Th17) T-cells and regulatory T-cells. As such, it shifts the immune system towards a state of chronic low-grade inflammation. Dysbiosis also weakens the gut barrier, creating a self-reinforcing cycle.
Stress has been shown to cause long-term changes in tight junctions; certain antibiotics have also been demonstrated to create long-term effects on tight junctions. The high amounts of processing found in today’s diets are contributing to damage to the tight junctions, and for some people, the presence of gluten has been found to cause damage to tight junctions.
