Leaky Gut – AIBA Advanced Intestinal Barrier Assessment

Leaky Gut – AIBA Advanced Intestinal Barrier Assessment

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 created from many years of experience by 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

At Smart Nutrition we pride ourselves in offering the best cost possible for the Advanced Intestinal Barrier Assessment test.

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 autoimmunity
  • Altered mood/depression

Further information


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. Itspresence 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. 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, oestrogen 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’s important to also consider histamine intolerance.

High histamine levels are associated with the following symptoms and conditions:

  • Severe allergic reactions (anaphylaxis)
  • Low muscle tone
  • High blood pressure
  • Dizziness
  • Headache
  • Nausea, vomiting
  • Diarrohea, gas
  • Intestinal cramps
  • Painful menstruation
  • Shortness of breath
  • Congestion, runny nose, sneezing
  • Hives, itching, flushing
  • Abnormal heart rate
  • Changes in:
    • Circadian rhythm
    • Body temperature
    • Food intake
    • Learning
    • Memory

Low histamine levels are associated with the following symptoms and conditions:

  • Fatigue
  • Depression
  • Sleep-wake disorders such as narcolepsy

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.

Lipopolysaccharides (LPS) IgA, IgG, IgM

The body makes different antibodies or immunoglobulins (Ig) to protect against bacteria, viruses and allergens, including LPS.

IgM – The first immunoglobulin or antibody made when fighting a new infection is IgM; this is the early infection response. IgM clears the body more quickly than IgG.

IgG – Following that, usually around 7-14 days later, you mount immunoglobulin G. The IgG response is the later response and is a longer-lasting immune response. IgG is the most common antibody and can take time to form after an infection.

IgA antibodies are found in the linings of the respiratory tract and digestive system, as well as in saliva, tears and breastmilk.

If these markers are reported as high it indicates the immune system is actively fighting bacterial overload. Treatments include antimicrobials to lower the bacterial load.

Low LPS antibodies are associated with an immune system that is chronically worn down. IBS and IBD can both be a result of an infection that was chronic and that has resulted in little to no immune reserve which can be highlighted by this test.



The the Advanced Intestinal Barrier Assessment test measures:

  • DAO: histamine Ratio
  • Diamine oxidase (DAO)
  • Histamine
  • LPS IgA
  • LPS IgG
  • LPS IgM
  • Zonulin

For the Advanced Intestinal Barrier Assessment test, a fasting blood draw is required. Do not consume any food for 12 hours prior to the blood draw.


Before taking the Advanced Intestinal Barrier Assessment test, please discontinue all antihistamine medications for at least 5 days prior to your blood draw. Check with your GP before stopping any medication.

Freeze the cold pack 4-6 hours minimum before blood draw.




Age 3 years and above. Please bear in mind that the sample requires a blood draw which may be difficult for some paediatrics.

Gram negative overgrowth can happen at any age. However, the antibody response may be muted until 5 years of age. 

Patient Preparation

Antihistamines cannot be taken at least 5 days prior to this test.

Do not take steroids within one week of testing.

Do not discontinue with any medication unless supervised by your doctor

This is a fasting test. Do not consume any food for 12 hours prior to the blood draw. You may drink water. The kit will come with full instructions – please do read and follow these. 

Please book your courier 24 hours before your blood draw.

Sample requires centrifuging. If this is not possible the sample should only be drawn in the morning and returned to the lab the same day via a next day service to arrive before 1 pm. The lab will spin the sample on receipt.

Only return your samples Monday to Wednesday via the UPS service included with your test kit.

Your test results will be emailed to you.

Leaky Gut – AIBA Advanced Intestinal Barrier Assessment

related tests


Please do not return samples to the laboratories that may arrive after Wednesday 27th March and up to and including Monday 2nd April.

The laboratories are closed from the 28th March – 2nd April for the Easter Holiday.