Ceilings and boats can spring a leak. During heavy rainfall, water drips through a weak ceiling and ruins things that are supposed to be dry. A boat with a hole in it starts sinking because water seeps in where it shouldn’t be. Just like these analogies, your gut can become leaky and cause dysfunction in other parts of your body that are normally protected from inflammatory mediators flowing through the gut. 

Leaky gut and leaky gut syndrome are related concepts, but they are not the same. Leaky gut refers to a measurable biological condition where the intestinal lining becomes more permeable than normal. This occurs when the tight junctions between the epithelial cells in the gut weaken, allowing larger molecules like toxins, bacteria, and partially digested food to pass into the bloodstream. Increased gut permeability, or leaky gut, is a well-studied phenomenon and has been observed in conditions like celiac disease, inflammatory bowel disease (IBD), and chronic stress.

On the other hand, leaky gut syndrome is a broader and less defined term often used in alternative medicine to describe a set of symptoms believed to result from a leaky gut. Advocates of this concept suggest that increased intestinal permeability can lead to systemic inflammation and contribute to chronic issues such as fatigue, brain fog, food sensitivities, bloating, and autoimmune conditions. However, while leaky gut itself is a validated physiological condition studied in medical research, leaky gut syndrome is not universally recognized as a formal medical diagnosis. This distinction arises because the evidence linking leaky gut to a wide range of systemic health problems is still evolving and not fully conclusive.

In summary, leaky gut describes the actual biological state of increased gut permeability, which is recognized in the medical community. In contrast, leaky gut syndrome refers to a theoretical collection of symptoms thought to be caused by leaky gut, which remains controversial and lacks widespread clinical acceptance. If you suspect issues related to a leaky gut or experience related symptoms, it’s important to consult a healthcare provider for an accurate diagnosis and appropriate treatment.

The gut is lined with a single-cell layer of epithelium with tight junctions and other cell-to-cell structures between each of the gut epithelial cells. These tight junctions maintain the barrier between the gut and the bloodstream and also regulate gut permeability, allowing for ions to pass through, but not larger compounds. There are multiple proteins, such as zonulin and claudin proteins, that maintain the gut barrier and compounds we ingest can modulate the expression of these proteins to alter gut permeability. For example, gliadin, a protein in wheat, can cause zonulin to be released into serum, thus decreasing the integrity of tight junctions. This leads to increased gut permeability and happens in celiac disease.

Once gut permeability is increased, endotoxins, such as lipopolysaccharide (LPS) can leak from the gut and cause inflammation in other body areas. LPS is a lipid found in gram-negative bacteria and is recognized by innate immune cells to trigger an anti-microbial response against the pathogen. This explains why celiac disease leads to symptoms like an upset stomach and headaches as endotoxins can travel by the gut-brain axis to cause inflammation in the brain. Dysregulated intestinal permeability has been implicated in other neurological and psychiatric diseases as well as liver diseases, demonstrating the effects that it can have all over the body.

While brief inflammation helps to clear infections, chronic inflammation is what leads to a whole host of diseases, damaging the body. Thus, having a constant leaky gut can contribute to inflammation throughout the body. Increased gut permeability has clearly been indicated in inflammatory bowel disease and other gut inflammatory disorders. There are still portions of it being uncovered in brain and mood disorders, but as mentioned earlier, endotoxin can travel to the brain and cause neuroinflammation which is implicated in Alzheimer’s disease and depression.

The main question is if we can do anything to maintain our gut barrier. The following are some of the proposed ways to maintain gut barrier integrity based on current research:

1. Fiber: Within the gut microbiome, there are “good” microbes that ferment dietary fiber into short-chain fatty acids (SCFAs). One of these SCFAs is butyrate which is used as an energy source to cells in the gut. Butyrate is beneficial for gut health in various ways, for example by improving the assembly of tight junctions. Fiber is found in many fruits and vegetables as well as grains, like oats and wheat, and mushrooms.
2. Probiotics: Certain probiotic strains have been implicated in decreasing gut permeability by modulating the expression of tight junction proteins. Two of these stains include Lactobacillus plantarum and E. coli Nissle, which may be found in certain probiotic supplements or fermented foods. While this is a promising treatment, investigation is still underway to clearly understand the use of probiotic treatment for gut permeability and inflammatory gut disorders.
3. Exercise: Exercise is a form of hormetic stress, which is temporary stress that reaps benefits in the long term. During exercise, muscle fibers are destroyed, but the body’s repair mechanisms grow them back stronger than before thus demonstrating “good stress”. Similarly, it has been suggested to be a type of hormetic stress for gut health. Initially, gut permeability increases after exercise, but some studies have shown improved gut barrier integrity in the long term after a consistent exercise routine. Further research is needed to clarify the relationship between intestinal permeability and exercise.

Testing for leaky gut involves various methods to assess gut permeability and overall gut health. One common approach is zonulin testing, which measures zonulin levels, a protein that regulates the tight junctions in the intestinal lining. Elevated levels in stool or blood samples may indicate increased intestinal permeability. Another widely used method is the lactulose-mannitol test, a urine-based test that evaluates the absorption of two sugar molecules; abnormal results can suggest compromised gut barrier function. Additionally, some advanced gut health testing kits, such as the ones offered by Vitract, analyze the gut microbiome using genomic sequencing. These kits provide a comprehensive view of the gut’s bacterial diversity, metabolic markers, and potential signs of inflammation or permeability issues. By combining these tests, individuals can gain valuable insights into their gut health and take steps toward restoring gut integrity.