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Leaky Gut / Intestinal Permeability

IBS and SIBO Clinics  >  Digestive Conditions  >  Leaky Gut / Intestinal Permeability

What is leaky Gut?

Leaky gut also known as intestinal permeability, where the single-thickness cells of the Gastro intestinal tract inner lining move slightly apart and stay apart for extended periods – These tight junctions are usually pulled together by tight junctions that act a little like a shoe lace. As well as in between the cells we also know due to research by Alessio Fasano that there is leakiness through the cells and this can potentially lead to normal gut bacteria and toxins to cross into the bloodstream and create an immune response. (Ref)

It is known, thanks to research by Dr Fasano, that gluten, a molecule within wheat, activates the zonulin amino acid within the cell junctions of the GI tact, causing them to widen and thus become more permeable. For this reason, many practitioners will recommend eliminating gluten from your diet in the short term, while your gut improves.

The symptoms of Leaky gut are often hard to differentiate from other complex multi faceted conditions and it rarely stands alone and makes up part of a comprehensive health picture but it can lead to a variety of symptoms including, bloating, flatulence, cramps, food allergies/ sensitivities and joint aches and pains, sleeping issues, depression, skin issues, brain fog,  and fatigue plus it is known to play a part in immune dysregulation, inflammation and auto immune diseases.

Possible contributory Factors

  • Underlying chronic condition eg, Crohn’s, Diabetes or Coeliac disease
  • SIBO – Small Intestine bacterial overgrowth – up to 50% of people with SIBo have permeability
  • SIFO – Small intestine fungal overgrowth
  • Regular use of NSAID’s (non-steroidial aniti-inflammatory drugs), PPI’s (Protein pump inhibitors) and similar medications.
  • Regular use of antibiotics, which over time can disrupt the gut microbiome.
  • Chronic stress – meditation can help.
  • Excessive sugar intake, which can harm the barrier function of the intestinal wall.
  • Excessive alcohol intake.
  • Nutritional deficiencies, particularly in vitamins A and D and zinc.
  • Chronic inflammation.
  • Poor gut health and or poor digestive function
  • Yeast overgrowth and/or Candida.


There are a few steps to treating leaky gut

Step 1. They key question to ask if you have a leaky gut is to find out “Why do I have a leaky gut” and address the root cause of the problem. Patching up a leaky gut with expensive supplements without addressing the why is going to be frustrating experience and is unlikely to fix the problem. In our IBS and SIBO clinic the sequence of these steps may be taken one at a time or may be grouped together depending on you and your individual case.

Investigating the root cause could include stool and breath testing to look for drivers of permeability and inflammation such as candida, gluten sensitivity, SIBO, SIFO or parasites

Step 2 – Remove the unhelpful inflammatory foods and any contributory lifestyle choices.

For example to start to improve your gut health, begin by limiting your intake of processed foods, in particular those that are high in refined carbohydrate and high in sugar.

Limiting the use of NSAID’s but addressing the root cause of gut discomfort can help also.

Step 3 – Increase anti- inflammatory beneficial foods and positive lifestyle choices

High fibre plants and eating a good diversity of fruits and vegetables support good gut health.

Probiotic supplements can be beneficial in correcting imbalances in the gut microbiome or any gut dysbiosis (imbalanced bacteria). Initially these are generally not recommended if you are also dealing with SIBO or SIFO.

Fermented foods such as organic yoghurt. Kimchi, kefir, sauerkraut and kombucha can also help to improve gut health but these are generally not initially recommended if you are also dealing with SIBO or SIFO.

Bring in stress management techniques and address work life balance

Step 3  – Repair the gut.

Testing for leaky gut

Advanced Intestinal Barrier Assessment (AIBA)

About this test

The Advanced Intestinal Barrier Assessment is a useful profile to consider if you suspect you have intestinal permeability or ‘leaky gut’ and want to know what imbalances may be driving that process. This test was designed out of years of practice of integrative practitioners who recognise we can improve health by improving the gut through diet and other interventions.

This is the only profile on the market that assesses this combination of markers as possible drivers of intestinal permeability:

  • Zonulin
  • Histamine
  • Diamine Oxidase (DAO)
  • Lipopolysaccharides (LPS) IgA, IgG, IgM

Why do the AIBA Profile?

Key symptoms which suggest this profile could provide valuable clinical information include:

  • Symptoms suggestive of food intolerance
  • Symptoms suggestive of chemical hypersensitivity
  • Symptoms suggestive of elevated histamine/histamine intolerance
  • Symptoms of fatigue
  • Eczema/frequent skin rashes/urticaria
  • Previous diagnosis/suspicions of auto-immunity
  • Altered mood/depression

What is being measured?


Zonulin is a protein that plays an important role in the opening of small intestine tight junctions. This molecule is used as a non-invasive marker of gut wall integrity. The presence of zonulin suggests an increase between the intestinal cells gap junction, causing zonulin to be secreted.  It is an early marker of disease, elevating 2-5 years in advance of autoimmune, diabetes and allergic diseases.

Stool zonulin levels need to be shown in context of other permeability markers and current presenting symptoms. Whereas blood zonulin levels are well researched to show intestinal permeability as demonstrated in papers by the zonulin pioneer Dr Fasano.

Diamine Oxidase (DAO)

Diamine oxidase (DAO) is the body’s primary enzyme for breaking down ingested histamine and a natural defence against histamine excess. If you ingest too much dietary histamine or produce more than your DAO level can handle, reactions can occur. DAO is produced in the microvilli of a healthy small intestine, certain drugs, foods, and bacteria may suppress its production.

Low levels of DAO are associated with the following symptoms and conditions:

  • Migraine, headache
  • Chronic fatigue
  • Hives, skin rash, eczema, psoriasis
  • Nasal congestion, asthma
  • Gastrointestinal disorders, inflammation, irritable bowel syndrome
  • Dysmenorrhea, PMS, estrogen dominance
  • Arrhythmia, hypertension, hypotension
  • Fibromyalgia, muscular pain
  • Rheumatoid arthritis
  • Neurological conditions such as multiple sclerosis and attention deficit and hyperactivity disorder (in childhood and adolescence)
  • Depression and anxiety


Histamine is involved in many types of allergic and inflammatory processes, including immediate and delayed hypersensitivity reactions. Histamine imbalances in the body may cause a variety of adverse effects ranging from life-threatening allergic reactions to localised itching, runny nose or hives.

An excess of histamine may be a result of ingested histamine (from certain foods), released histamine from storage sites in the body due to food or environmental triggers, or a diamine oxidase (DAO) deficiency which is needed for the breakdown of histamine. Testing histamine along with diamine oxidase (DAO) levels provides important information that standard food sensitivity tests may not reveal. When suspecting food sensitivities, it can be important to also consider histamine intolerance.

DAO: Histamine Ratio

The DAO: Histamine ratio helps identify the imbalance between DAO and histamine levels. Even if DAO is reported as normal, if histamine is high, symptoms can still occur.

A low ratio can provide evidence of insufficient levels of DAO enzyme activity relative to the current level of histamine in the body.

Lipopolysaccharides (LPS) 

In humans, the presence of LPS triggers can trigger an immune response producing inflammation.

LPS are found on the outer surfaces of some gut bacteria and when found in the blood, it means they are passing not only between intestinal cells, but also directly through the cells, potentially causing inflammation.

Elevated levels may be associated with bacterial infection, food sensitivities, chronic inflammation, autoimmune conditions, digestive disorders, and neurological conditions.