Leaky gut or increased intestinal permeability has become a hot topic in the recent past. Some people see it as a trend term while the others see it as a real medical issue that may be related to several comorbidities. In my capacity as a gastroenterologist and gut health physician, I will first explain what leaky gut is and why it develops.

Leaky gut is a condition when the walls of the small intestine become more permeable than they should ordinarily be. Usually, the lining of the at small the intestine acts as a barrier not allowing pathogens, toxins or undigested food particles into the blood stream.   The function of the small intestine is to absorb nutrients and when functioning properly only nutrients and water enter the blood stream.   This important barrier function is provided by intercellular junctions which are proteins that keep the gaps between the intestinal cells tight.

In leaky gut, the tight junctions have been altered, thus allowing larger molecules to leak into the intestinal wall and get into the blood stream. This increase in permeability can lead to an immune response; this may in turn lead to inflammation and other health complications.  How does this occur?  If unwanted particles can enter the bloodstream, the job of the immune system is to detect and remove them.  The immune system can mount an immune response. If unregulated this response can become chronic, this can become chronic inflammation which is the foundation of all disease. If the unwanted particle which crossed into the bloodstream has molecular similarity to a part of the body, the immune system can recognize this body part as foreign as well and mount an immune response which becomes autoimmune.

Science of Intestinal Permeability – Anatomy

• Epithelial Cells:  The inner lining or the intestinal epithelium is made up of a layer of cells that act as the first barrier against foreign substances.
• Tight Junctions: These are protein structures that pull the epithelial cells closer hence preventing the opening of intercellular spaces to only allow certain substances through.
• Mucosal Layer: This layer of mucus lies on top of the epithelial cells and is also a barrier, in addition to being a place for bacterial flora.
• Gut‐Associated Lymphoid Tissue (GALT): This is a part of the immune system that is in the gut and can identify and react to potential pathogens in the gut.

When the integrity of the tight junctions is affected, the gut lining becomes ‘leaky’ which means that toxins and other unwanted substances can get into the blood stream. This phenomenon is referred to as increased intestinal permeability also known as “leaky gut.”

Causes of Leaky Gut

Several factors can contribute to increased intestinal permeability. Here are some of the most common:

1. Dietary Factors

• Processed Foods: sugars, fats and, preservatives, pesticides and other additives in the standard diet can affect the gut barrier’s function.
• Gluten: In celiac disease patients or those with gluten sensitivity, gluten acts on zonulin, a protein that regulates intercellular junctions and therefore leads to increase in permeability.
• Alcohol: Increased alcohol consumption is also known to cause an inflamed lining of the intestine and an unbalanced gut flora.

2. Gut Dysbiosis

Dysbiosis is an imbalance of the gut microbiota, the population of bacteria, viruses, and fungi that live in the gastrointestinal tract.  It can also contribute to the development of leaky gut syndrome. It is important to note that harmful bacteria can release toxins that can destroy the lining of the intestinal wall.  If there are fewer good bacteria, there is less protection in the mucosal layer.  Dysbiosis can occur from many reasons, most commonly from medications such as antibiotics and proton pump inhibitors, a poor diet, stress, and poor sleep.

3. Chronic Stress

Stress has been proven to have a negative impact on the tight junctions of the intestinal epithelium through increased levels of cortisol.

4. Medications

Some medications can impact the lining of the gut directly.  Nonsteroidal anti-inflammatory drugs (NSAIDS) are commonly prescribed and over the counter drugs which can directly affect the lining of the gut. These medications such as aspirin, ibuprofen, naproxen, diclofenac, celecoxib, mefenamic acid, etoricoxib, and indomethacin may cause irritation and alteration of the intestinal mucosa and microbiota therefore increasing the risk of leaky gut.

5. Chronic Inflammation

Pathological conditions including Inflammatory Bowel Disease (IBD) such as Crohn’s Disease and Ulcerative Colitis as well as food allergies result in inflammation of the gut mucosa.  Over time these can result in breakdown of the tight junctions.

6. Toxins

Exposure to toxins such as pesticides, heavy metals, can also affect the intestinal lining and thus lead to leaky gut.

Signs and Symptoms of Leaky Gut

Leaky gut is not a specific disease but rather a condition that may play a role in the development of several other diseases. Common signs and symptoms include:

• Digestive issues such as bloating, gas, diarrhea, or constipation
• Food sensitivities or intolerances
• Fatigue and brain fog
• Skin conditions including eczema or acne
• Joint pain & muscle aches
• Autoimmune diseases include rheumatoid arthritis, Hashimoto’s thyroiditis and many others.

These symptoms and conditions, however, are not distinct and can be linked with other diseases, thus it is crucial to consult with a doctor for proper diagnosis.

Leaky Gut and Its Relationship with Chronic Diseases

Emerging perspectives indicate that leaky gut can be related with the onset or worsening of various chronic diseases, including:

1. Autoimmune Diseases

Leaky gut has been identified as one of the primary causes of autoimmune diseases. When toxins which were absorbed due to increased intestinal permeability appear in the bloodstream, they can lead to an immune response in which the body attacks its own tissues. Some examples are celiac disease, type 1 diabetes and multiple sclerosis which have been linked with leaky gut.

2. Metabolic Disorders

Leaky gut has been linked with metabolic disorders such as obesity, insulin resistance and type 2 diabetes. These conditions may be result from the chronic low-grade inflammation that results from increased intestinal permeability.

3. Mental Health Disorders

The gut-brain axis is the association between the gut and the brain and how one affects the other in terms of health.  Increased permeability may allow inflammatory cytokines to get into the brain and thus play a role in the development of mood disorders such as depression, anxiety and cognitive decline.

Diagnosing Leaky Gut

Leaky gut is still not well established as a specific disease entity.  Below are some of the teats used.

Lactulose-Mannitol Test: This is the most common test to attempt to diagnose leaky gut. It determines the ability of two sugars to be absorbed to determine the permeability of the gut. 

Zonulin Levels: High levels of zonulin in the blood, a protein that regulates the tight junctions, may be associated with increased permeability.

Comprehensive Stool Analysis: This test gives a picture of the microbial population in the gut, levels of inflammation, and other markers of intestinal health.

These tests can be used to provide a better idea of the processes occurring in the gut at the time of the test but are not diagnostic.  In fact, there is no good diagnostic test and a person’s symptoms, and medical history should all be considered when attempting to find a root cause for a health problem.

Managing and Healing Leaky Gut

While the science of leaky gut is still developing, there is much that can be done to support the gut and maintain the integrity of the lining of the small intestine. 

1. Adopt a Gut-Friendly Diet

• Emphasis should be on eating more natural, clean foods, fibers, antioxidants, and fatty acids in the diet.
• Include probiotic and prebiotic foods in the diet to maintain a healthy gut flora.
• Eliminate certain food groups.  Common culprits may include gluten, dairy products, ultra-processed foods, and sugar.

2. Address Underlying Conditions

Assist the patient to identify and manage any other conditions that may be present including infections, food allergies, and autoimmune diseases .

3. Reduce Inflammation

Incorporate anti-inflammatory foods into your diet such as fatty fish, turmeric and leafy green vegetables. Omega‐3 Supplements in fish oils and flaxseed oils may be helpful.

4. Improve and Support Gut Barrier Function:

• L-Glutamine: This is a nonessential amino acid which is very essential in the process of repairing the intestinal the lining and maintaining intestinal integrity.  Glutamine rich foods include bone broth and eggs.
• Zinc deficiency has been associated with increased intestinal permeability and supplementation can be helpful.  Zinc rich foods include eggs, beef, and legumes
• Collagen is also helpful in healing the gut. Bone broth is rich in collagen.

5. Manage Stress

Engage in stress reducing activities such as yoga, meditation, regular exercises and breathwork to reduce cortisol levels and improve the health of the gut. Adequate sleep is also vital to help with stress

management.

6. Avoid Gut‐Disrupting Medications

Try to limit the use of NSAIDs and antibiotics.  Use these drugs with caution and only when necessary.  

A Glimpse of the Future: Leaky Gut Research in the Next Generation

This condition is still in the initial stages of being discussed in the medical field, and more research needs to be conducted to establish the link between leaky gut and various diseases. New insights in the microbiome. genetics, new diagnostic tests may be useful.  

Final Thoughts

Leaky gut is a rather complicated phenomenon, which has a tremendous potential to impact someone’s health in many ways.  Although it has not been established as a medical condition, the current literature discusses its possible association with several chronic diseases. As a gastroenterologist, I urge people with chronic or concerning symptoms to seek help.  In this way, we can work together and determine the root causes of the symptoms and come up with a plan that will improve a patient’s gut health and overall health.