What is Leaky Gut?

Written by Dominique Johansen, Naturopath at Brisbane Livewell Clinic, 10 June 2024

What is Leaky gut?

Leaky gut, a term that most naturopaths, nutritionists, and other complimentary health practitioners are probably remarkably familiar with. Although the term Leaky Gut might not be commonly recognised by modern medicine, the condition certainly is. Modern clinicians appropriately refer to Leaky gut as "Increased intestinal permeability" or "Intestinal epithelial barrier dysfunction". Both adequately describing the condition.

In the last 20 years there has been a dramatic rise in the number of published studies on increased intestinal permeability/leaky gut. In the year 2000 there was not a single medical paper published on PubMed regarding increased intestinal permeability/leaky gut. The rise began in 2015, where the papers on the topic doubled from the previous year, and the papers have continued to grow since.

Leaky gut has been linked to several illnesses, of the digestive tract and systemically. Conditions such as Rheumatoid arthritis, Inflammatory bowel disease (IBD), Rosacea, (and other inflammatory conditions), Irritable bowel syndrome (IBS), Non-alcoholic fatty liver disease (NAFLD), Alcoholic fatty liver disease, Liver cirrhosis, Severe acute pancreatitis (SAP), Hormonal imbalance, Type 1 and Type 2 diabetes, Depression, Parkinson’s... the list goes on. (Source)(Source)

Has this condition been with us all along, sliding under the radar of medical professionals without being recognised? Is it the cause of the diseases listed above and many more?

Read about What is Leaky Gut Australia?

Leaky gut/increased intestinal permeability is a condition that effects the integrity of the gastrointestinal tract (GIT) lining. The GIT begins with the mouth and continues down the throat, oesophagus, through the stomach, small and large intestine, the rectum, and the anus.

Leaky Gut however is localised to the small and large intestine. Obvious symptoms that may be associated with Leaky Gut are generally seen in the digestive tract, where gas, bloating, and digestive disturbances are often the first symptoms.

The condition is as it sounds, which results in substances “leaking” out from the intestine (gut), but how does this happen?

The intestinal lining is a made up of a combination of cells called the epithelium. These cells are responsible for secreting substances, absorbing others, and inhibiting invading pathogens. They do this by opening and closing when required, allowing passage for some, and blocking out others. (Source)

This intelligent function of our cells can become compromised if they are exposed to the contents in our intestine. Sound unusual? Isn't this where we absorb nutrients? wouldn't the food need to be in contact with the intestinal lining? Not quite.

What is a healthy, well-functioning gut like?

First, we need to understand what is happening in a healthy, well-functioning gut.

In a healthy intestine this cell lining is covered by a protective barrier, made up of different components that shield the intestinal lining from damage. The makeup of this protective barrier differs slightly between the small and large intestine.

A healthy small intestine is made up of 5 main components

1. Outer loose mucus

A layer of mucus that is not attached to the intestinal wall. This layer is responsible for protecting the intestinal lining from invading pathogens and serves as a food source for the microbiota.

2. Secretory Immunoglobulin A (Secretory IgA)
This is also known as an antibody; its role is to protect the intestinal lining from toxins and invading pathogens.
This immunoglobulin is often reduced in people with food sensitivities, poor diet, stress, Chronic fatigue syndrome, Coeliac disease, and Leaky gut.

3. Antimicrobial peptides (AMP’s)
These are chains of amino acids produced by the epithelium. They protect the intestinal lining by defending against undesirable bacteria.

4. Commensal bacteria (Microbiome)
The layer of the barrier that everyone would be familiar with. These are our beneficial bacteria, they serve an important role in food digestion, immune response, energy, mood regulation and so much more.

5. Epithelium/Intestinal lining
This is the intestinal lining or intestinal wall. Here substances are secreted to maintain the previous layers, nutrients are absorbed from digested foods. These are the cells that open to allow passage and are intended to close.

While the large intestine is structured slightly differently, with 6 different components. Like the small intestine, the presence of surface mucus, Secretory IgA, AMP’s, and commensal bacteria all remain. With the addition of an inner mucus layer. Similar to the other layers, the inner mucus inhibits invading pathogens and microbes, acting as the last defence before the intestinal lining.

Unlike the loose surface mucus, inner mucus is attached to the lining/epithelium layer and is not intended to detach. (Source)(Source) Together this combination of layers and components maintain the integrity and function of the gut. (Source)

If any one of these normal protective components of the intestinal barrier are compromised the intestinal lining will be exposed to the contents of the gut.

This changes from person to person but will generally include digesting foods, bacteria, fungus & parasites. These items have the ability to open the cells in the intestinal wall, allowing them to pass through and into circulation. These cells can remain open for some time, continuing to allow the passage of foreign substances into the bloodstream (directly below the intestinal lining). (Source)(Source)
This is what is referred to as a Leaky gut.

Once the foreign substances have reached the bloodstream, they travel through the circulatory system, causing inflammation along the way and sometimes making their way to specific organs or joints causing further inflammation and destruction to that area. (Source)(Source)

The most common cause of disruption to the intestinal barrier is understood by both modern & traditional practitioners to be exposure to aggravating factors. Poor dietary choices, certain medications, inflammation, stress, GIT disorders and excess alcohol consumption can all play a role in damaging and reducing function of the intestinal barrier, leaving the intestinal wall exposed and with the potential for "leaks" to occur. (Source)

The good news is that this condition can improve, the body is miraculous and can repair if given the correct environment. Barriers can be restored, bacterial imbalances corrected, gut lining damage or “leaks” reduced. The benefits of addressing and improving Leaky gut could be far greater than digestive symptoms.  

You can support and restore the integrity of your gut by implementing a few changes. Starting with removing foods and other problematic items from the diet, reducing stress and exposure to toxins, supporting gut health with appropriate probiotics, prebiotics, nutrients, polyphenols, and adequate hydration.

References

Anderson, G., Seo, M., Berk, M., Carvalho, A. F., & Maes, M. (2016). Gut Permeability and Microbiota in Parkinson's Disease: Role of Depression, Tryptophan Catabolites, Oxidative and Nitrosative Stress and Melatonergic Pathways. Current pharmaceutical design, 22(40), 6142–6151.

Arrieta, M. C., Bistritz, L., & Meddings, J. B. (2006). Alterations in intestinal permeability. Gut, 55(10), 1512–1520. https://doi.org/10.1136/gut.2005.085373

Camilleri M. (2019). Leaky gut: mechanisms, measurement and clinical implications in humans. Gut, 68(8), 1516–1526. https://doi.org/10.1136/gutjnl-2019-318427

Di Tommaso, N., Gasbarrini, A., & Ponziani, F. R. (2021). Intestinal Barrier in Human Health and Disease. International journal of environmental research and public health, 18(23), 12836. https://doi.org/10.3390/ijerph182312836

Kinashi, Y., & Hase, K. (2021). Partners in Leaky Gut Syndrome: Intestinal Dysbiosis and Autoimmunity. Frontiers in immunology, 12, 673708. https://doi.org/10.3389/fimmu.2021.673708

Paone, P., & Cani, P. D. (2020). Mucus barrier, mucins and gut microbiota: the expected slimy partners?. Gut, 69(12), 2232–2243. https://doi.org/10.1136/gutjnl-2020-322260Gut 2020;69:2232-2243.

Ravinder Nagpal, Hariom Yadav; Bacterial Translocation from the Gut to the Distant Organs: An Overview. Ann Nutr Metab 26 September 2017; 71 (Suppl. 1): 11–16. https://doi.org/10.1159/000479918