This condition is becoming increasingly prevalent and is now understood to be an underlying factor in autoimmune conditions and many allergies and food sensitivities. People with eczema, psoriasis, headaches/migraines, brain fog and achy joints, may all have a degree of leaky gut, or a hyper-permeable gut lining – to give it its technical term.

‘Eating & Living Gluten-Free’ magazine recently commissioned an article, because of the association between gluten, leaky gut syndrome and Coeliac disease. Read on . . .  


What is ‘leaky gut’?

Describing the gut as ‘leaky’ may seem obvious, even somewhat absurd, given that the gut is supposed to be permeable, how else would we absorb dietary nutrients?  However it is the degree of permeability that will determine whether or not the gut is healthy.

Our gut lining actually has a dual role, to provide a barrier to bacteria and microbes, whilst absorbing nutrients from food.  It is when the barrier function is performing poorly that we can describe it as leaky.  Ideally a healthy gut lining should be like fine cheesecloth, only allowing through and tolerating fully digested food-derived molecules.  A hyper-permeable, or ‘leaky gut’ is behaving more like a colander, giving passage to larger, only partially digested food particles, as well as toxins and microbes that would have been blocked by a healthy gut lining.

Gut barrier function

A healthy gut’s first line of defence is a thick mucus layer, abundant with bacteria that live symbiotically with us, assisting our digestion and synthesising useful nutrients.  Many things can temporarily disrupt this barrier, but our innate immune system, residing just the other side, provides an instant army of immune cells ready to engulf and destroy any intruding bacteria or viruses.  Similarly, our adaptive immune system will tag any unwanted intruders, with a view to making antibodies that it can call on in the future, should the invaders make another appearance.  The occasional incursion keeps our immune systems primed, but a continual flood of antigens, undigested food and microbes from an overly leaky gut can produce inflammation, allergies, food intolerances and auto-immune conditions.1

Signs and symptoms:

Dr. Alessio Fasano, of the Centre for Coeliac Research at the University of Maryland Medical centre, attributes many gastrointestinal symptoms like bloating, indigestion, diarrhoea and lowered nutrient absorption, to gluten and leaky gut syndrome, as well as neurological symptoms like brain-fog, forgetfulness, and depression.2

                    L E A K Y   G U T   S Y M P T O M S


Symptoms within the intestines 


Symptoms outside the intestines 


Poor digestion


Stomach cramps

Fat in the stool


Unexplained weight loss

Sinusitis, Eczema, Psoriasis

Arthritic conditions, joint pains

Anaemia, Chronic fatigue


Brain fog, migraines


Auto-immune conditions

 The causes of leaky gut

There are many contributory factors (see the table below), but in a nutshell, anything that causes inflammation in the intestine, or disrupts its microflora and barrier function.  Our intestines interface with the outside world, and we bombard them with far more than the simple foods our ancestors would have recognised.  Regular use of pain-killers, antibiotics or alcohol, can typically disrupt or reduce the protective bacteria,6,7 and now research has identified a particular issue with gluten.8

                                        Causes and contributory factors to leaky gut

Frequent consumption of

inflammatory foods

A high intake of alcohol

Wheat & Gluten containing grains

Legumes (contain lectins)

Sugar and refined carbohydrates

For some;

Nightshade plant family and dairy


Antibiotics (reduces diversity of gut bacteria)

NSAIDs (asprin/Ibuprofen/painkillers)7


Acid blocking drugs (reducing stomach acid inhibits digestion & favours survival of pathogens)

Chemotherapy, radiation, surgeries

Gut infections:Stress:
Gastroenteritis (with diarrhoea)


Overgrowth of Candida species

SIBO (small intestinal bacterial overgrowth of pathogenic bacteria from large intestine)

Mycotoxins (toxic moulds)

Acute emotional stress

Chronic work-related stress

Physical stress (e.g. excessive exercise, or high intensity over-training)

All types of stress lowers the innate immune defence (secretory IgA) of mucosal tissue

Gluten and Gliadin

Recent studies show that gliadin, a protein in gluten, can actually increase gut permeability.8  It helps to understand how the intestine is structured.  Its surface cells have – at intervals – cells called ‘tight junctions’.  These are dynamic structures governed by a protein called zonulin which regulates the traffic of molecules passing through.  Unfortunately, zonulin becomes elevated by gliadin, leading to increased stimulation of tight junction opening, making them more leaky.8  Research shows zonulin to be particularly elevated in the serum of celiacs.However, removing gluten from the diet decreases zonulin, allowing the gut’s barrier function to be restored, with levels of gliadin antibodies becoming normalised.2

Stress and leaky gut

Stress deserves a special mention because of how it directly affects the gut’s immune system. All types of stress lowers the body’s production of an immune molecule called secretory IgA, which has an important job effectively guarding mucosal tissue throughout the body. Secretory IgA is the immune system’s first line of defence against unwanted intruders (pathogenic bacteria and viruses), that arrive in the mucus lining the surface of the intestines, and it facilitates their removal.10 It’s worth noting, illness and many respiratory infections are more common after major emotional stresses, and leaky gut is more prevalent amongst over-trained (stressed) elite athletes11, in part because this protective immune molecule becomes suppressed. It could also explain why psoriasis and eczema flare with stress and why the development of an autoimmune condition often follows a period of acute emotional stress.12 In a nutshell, our skin/tissue barriers are not so well protected in times of stress.

Tests for leaky gut:

If gluten sensitivity is suspected as a contributory factor of the leaky gut, Cyrex Laboratory is the go-to lab for Nutritional Therapists, due to the higher sensitivity and specificity afforded by their testing of many more fractions of the wheat and gluten proteins, meaning cases of undiagnosed Coeliac Disease have a better chance of getting identified with this test. If antibodies are being made to gluten, it goes without saying that the individual concerned has leaky gut. The same Lab offers a straight Intestinal Permeability blood test that will show if you are making antibodies to all sorts of undigested proteins, bacterial antigens and other molecules like zonulin, associated with a breach in the intestinal lining.

IgG food specific intolerance testing is a slightly cheaper skin-prick blood analysis. The theory being that the foods you are intolerant to, i.e.making an IgG reaction to, should imply which undigested foods are prematurely crossing a leaky gut, but the jury is out as to the sensitivity and accuracy of this form of testing.

The Mannitol/Lactulose test is the cheapest and historically the most common test for Intestinal Permeability, involving drinking a liquid containing lactulose and mannitol, that will not get metabolized, but pass through to the urine. Depending on which of the two sized molecules are better absorbed, and/or appear in your urine, intestinal permeability and malabsorption can be evaluated..

Of course one should not lose sight of individuality, nor context.  In the general population, wheat and gluten can be inflammatory for some and not others, and some people recover healthy levels of gut flora after a course of antibiotics, others don’t, especially if there have been multiple courses.  Gut leakiness can be transitory, if ‘insults’ are counterbalanced, for the gut has a great capacity to repair, given the right tools. For example, following a course of antibiotics with a therapeutic-strength course of probiotics that a professionally trained nutritionist can provide, can help safe-guard the integrity of the gut barrier.13

Reduce your risk

Clearly if the causes of your leaky-gut are not addressed or removed, no amount of gut healing therapy will work whilst the ‘insults’ are still occurring.  A Nutritional Therapist will employ a four step process: 1) to identify and address an individual’s contributory factors (see table); 2) repair the intestinal surface, to address the ‘leakiness’ and stem the tide of antigens triggering the immune system; 3) optimise digestive function to break down proteins more efficiently; and 4) suggest improvements to the diet with additional probiotics to restore microflora and optimise gut barrier function.14  Certain lifestyle changes may need to be permanent, but the improvements to overall health that can be achieved once gut health is optimised, can make such changes very worthwhile.

References are available for this article, apply in writing.