What Exactly is a Leaky Gut?

April 9, 2019

What is Leaky Gut?

The term ‘leaky gut’ is a phrase that gets thrown around, but how many of us actually know what leaky gut even means?? I have broken down the process surrounding a leaky gut and unravelled the layers below to share with you – what is leaky gut and what is the relevance of leaky gut in everyday health.

It’s important to note that the term ‘leaky gut’ is not a medically diagnosed condition and leaky gut is an area of growing research.

Gut Structure

Firstly, let’s take a look at the structure of the gut. When I use the word gut in this instance, I’m referring to the small intestine. The small intestine is approximately 3 meters in length and forms part of the gastrointestinal tract (that’s everything in the gut from the oesophagus to the anus and in between!). The small intestine has a large surface area for absorption and digestion of nutrients – carbohydrates, fats, protein, vitamins and minerals.

Approximately 90% of all nutrient absorption occurs in the gut via the small intestine

The technical term for ‘leaky gut’ is intestinal permeability – essentially this phrase refers to how permeable the lining of your small intestine is.

It’s important to note that some level of leaky gut or intestinal permeability is a good thing – it is a natural part of the digestive process in the gut that allows nutrients digested to be released into the bloodstream and transported around the body. Gaps in the intestine lining in the gut are called tight junctions.

When the gaps in the tight junctions in the gut increase, this, in turn, increases the leakiness/permeability of the gut lining. And this is where the name leaky gut or leaky gut syndrome comes from.

What Happens to a Leaky Gut

A healthy gut lining will prevent potentially harmful substances from crossing the tight junctions in the gut and into the bloodstream. If tight junctions are increased then potentially harmful substances from the gut can enter the bloodstream. This can lead to an inflammatory response as your body’s innate ability to recognise invaders will naturally fire up an immune reaction. This has the potential to cause dysbiosis of the gut – a leading driver in modern disease (dysbiosis is a term used for an altered relationship with the host (the gut) and any associated microbes).

Maintaining healthy tight junctions in the gut plays an important part of disease prevention and whilst inflammatory responses are a normal part of healthy human gut function, when they consistently occur they can impact your baseline health with potential for a leaky gut. Take stress, for example, stress in small doses is absolutely fine, it can be damaging to your health when it happens frequently and become chronic.

Leaky gut syndrome has been implicated in the development of a number of digestive conditions such as coeliac, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), diabetes and food intolerances.

There are a number of potential causes of leaky gut or increased intestinal permeability and as with all things health-related, we are all built differently and all respond differently. The health of the gut is no different. Please note that although gluten is listed below, this is in no way a bread shaming article. There are people that can tolerate things better than others and plenty of people can eat bread without having a gut reaction.

Potential Causes of Leaky Gut

There are both genetic and environmental factors that can be implicated in a leaky gut. Stimulating the release of a protein known as zonulin has been identified as increasing intestinal permeability and implicated as a potential cause of leaky gut. Pathogens and gliadin can stimulate the release of zonulin (gliadin in a protein found in wheat-containing products – this is what I was referring to when I mentioned above no bread shaming).

  • Diet; alcohol, fructose, gluten and saturated fats can affect the gut.
  • Nutrient deficiencies; glutamine is particularly important for maintaining the structural integrity of the gut lining.
  • Medications; antibiotic use and NSAIDs such as nurofen can impact the gut lining.
  • Stress and intense levels of exercise can also affect the gut lining.
  • Gut microbiome; increased levels of pathogenic bacteria in the gut can compromise the gut lining.

Possible Signs and Symptoms of a Leaky Gut

  • Food sensitivities
  • Gastrointestinal discomfort, bloating, pain, diarrhoea and/or constipation
  • Skin conditions acne and dermatitis

The scientific research to date does leave the question does increased intestinal permeability or leaky gut cause disease or does disease cause increased intestinal permeability or leaky gut – so for now, I hope this article provides some factual context as to what exactly a leaky gut is.

I will follow up soon with a post on which particular nutrients are important to maintain a healthy gut lining and as always, I research topics as much as possible, but in a world where science is always evolving, if you see a study that might be relevant to this article and topic of gut health, I’d love to hear from you.


Amy Savage is a qualified Nutritionist with a Bachelor of Health Science in Nutritional & Dietetic Medicine and is available for consultations online and in Sydney CBD. Email for further details.

what is leaky gut

Recommended Reading:

Learn to look after your gut with this guide: Why Eat: Prebiotic Foods



Albert-Bayo et al. 2019, ‘Intestinal Mucosal Mast Cells: Key Modulators of Barrier Function & Homeostasis’, Cells,
Fasano, A 2012, ‘Intestinal Permeability and It’s Regulation by Zonulin: Diagnostic and Therapeutic Implications’, Clinical Gastroenterology & Hepatology,
Leech, B 2018, ‘Association between increased intestinal permeability and disease: A systematic review’, Advances in Integrative Medicine,
Samadi et al. 2018, ‘The role of gastrointestinal permeability in food allergies’, American College of Allergy, Asthma & Immunology,



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