What Exactly is a Leaky Gut?

April 9, 2019

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

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

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 from the oesophagus to 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 small intestine

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

Some level of intestinal permeability is a good thing – it is a natural part of the digestive process that allows nutrients digested to be released into the bloodstream and transported around the body. The structure of the gut lining is maintained by tight junctions. Simply put, when the gaps in the tight junctions increase, this, in turn, increases the leakiness/permeability of the gut lining.

Is it important?

A healthy gut lining will prevent potentially harmful substances from crossing the tight junctions and into the bloodstream (see diagram below). If the gaps in tight junctions increase then potentially harmful substances 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 response. 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).

What exactly is a leaky gut

Whilst inflammatory responses are a normal part of a healthy human function when they consistently occur they can impact your health. If you take stress, for example, stress in small doses is absolutely fine, however, it can be damaging to your health when it happens frequently.

Increased intestinal permeability is an area of growing research and studies have suggested that it is linked to the development of a number of digestive conditions such as coeliac disease, inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), diabetes and food intolerances. As the research in this area is still evolving, it is also a consideration highlighted in recent research as to whether a disease is the cause of increased intestinal permeability rather than increased intestinal permeability as a cause of disease.

Genetics is another consideration and as with all things health-related, we are all built from different genetic makeup and some of us have a tendency to be more susceptible to some things than others.

Potential Causes

Genetic and environmental factors have been implicated in increased intestinal permeability and I’ve detailed some areas below that have been highlighted in research.

  • Zonulin; zonulin is a protein that has been identified in increased intestinal permeability. Both pathogens and gliadin can stimulate the release of zonulin (gliadin in a protein found in wheat containing products).
  • Diet; alcohol, fructose, gluten and saturated fats.
  • Nutrient deficiencies; glutamine and zinc are particularly important for maintaining the structural integrity of the gut lining.
  • Medications; antibiotic use and NSAIDs such as Nurofen.
  • Stress/exercise; intense levels of stress or exercise at high intensity in high temperatures.

By no means, is this a list of things you need to avoid – these are potential causes that have been researched and can attribute to increased intestinal permeability.

Signs & Symptoms

Tuning into how you feel is an important part of identifying whether you are experiencing any signs and symptoms listed below. Again, if you are experiencing any of the below symptoms that doesn’t necessarily mean you have increased intestinal permeability at all and there are lots of different health concerns that identify with the same symptoms.

  • Food sensitivities (any of the gastrointestinal symptoms below).
  • Gastrointestinal discomfort, bloating, pain, diarrhoea and/or constipation.
  • Skin conditions acne and dermatitis.

The scientific research to date does leave the question if increased intestinal permeability causes disease or whether disease causes increased intestinal permeability – so for now, I hope this article provides some factual context as to what exactly a leaky gut is and if you have any questions, please feel free to contact me.

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 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 exactly is a leaky gut


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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