September 17, 2026, 7:57 am | Read time: 4 minutes
Abdominal pain, bloating, or diarrhea are often attributed to stress or poor diet. However, an impaired intestinal barrier could also be the cause. The intestinal mucosa plays a central role in this. It not only ensures that nutrients from food are absorbed but also protects the body from potentially harmful invaders. If this protective function is compromised, it can manifest in various ways. FITBOOK Editor-in-Chief Nuno Alves asked gastroenterologist and author Prof. Martin Storr about the signs and what affected individuals can do.
What is the role of the intestinal mucosa?
The intestinal mucosa lines the inside of the intestine and performs several important functions. On one hand, it ensures that nutrients and water from food can be absorbed. On the other hand, it forms an important protective layer between the body’s interior and the intestinal contents. This is crucial because the intestine contains not only food but also billions of bacteria, potential pathogens, and other foreign substances.
“The intestinal mucosa is far more than just a lining of the intestine. It forms a highly active interface between our body and the outside world, protecting us from potentially harmful influences,” explains Prof. Martin Storr.
Furthermore, the intestinal mucosa is a piece of the so-called intestinal barrier. This complex protective system also includes the mucus layer on the intestinal surface, the gut microbiome, and the gut-associated immune system. Together, they regulate which substances from the intestine are allowed to enter the body and which should be repelled. If this finely tuned system is disrupted, the protective function of the intestine can be compromised.
Signs of a compromised intestinal mucosa
Storr explains that a compromised intestinal mucosa can cause a wide range of symptoms. Typical ones include:
- Abdominal pain
- Bloating
- Diarrhea
- Irregular bowel movements
Depending on the cause, weight loss, fatigue, or nutrient deficiencies can also be signs.
Storr emphasizes: “Nonspecific symptoms alone do not allow conclusions about the condition of the intestinal mucosa. Detectable disruptions of the intestinal barrier are described in diseases such as celiac disease or chronic inflammatory bowel diseases.”
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The role of the intestinal barrier in irritable bowel syndrome
There is also evidence that the intestinal barrier may play a role in other diseases. “Studies suggest that the intestinal barrier may also play a role in other conditions, such as irritable bowel syndrome. This connection is being intensively researched,” explains Storr.
In this context, the term “leaky gut” is often mentioned–especially in social media and guides on gut health. According to the expert, this term oversimplifies the intestinal barrier. It is not a single “leak” but a complex protective system composed of several closely interacting components. In addition to the microbiome, this includes the mucus or mucin layer, which has received relatively little attention in the previously microbiome-focused discussion. “This is why the frequently used term ‘leaky gut’ should be viewed with nuance,” says Storr.
What helps the intestinal mucosa–and what doesn’t
The good news first: “The intestinal mucosa has a remarkable ability to regenerate,” says the physician. “The cells of the mucosa renew themselves within a few days.” However, Storr also emphasizes: “For sustainable improvement, not only the regeneration of the intestinal wall cells is crucial, but also the restoration of the entire intestinal barrier.” It is important to identify and appropriately treat the cause, which may require a strict diet, such as a gluten-free diet for celiac disease.
But a fiber-rich diet also indirectly supports the mucosa, as the bacteria in the gut produce short-chain fatty acids like butyrate from it, providing energy to the mucosal cells. Many manufacturers therefore offer supplements with fiber or so-called probiotics. However, Storr warns: “There is currently no convincing scientific evidence that over-the-counter probiotic preparations can specifically repair the intestinal mucosa. Increasingly in focus are so-called postbiotics, whose influence on the intestinal barrier is currently being researched.”