What does the science tell us about gluten and leaky gut?

Catchy headlines poke fun at the gluten-free ‘fad’, and many GPs still do not believe non-celiac gluten sensitivity could be contributing to their patients’ conditions. But what is gluten exactly and what does the research and clinical experience from nutritionists and Functional Medicine practitioners tell us?

Gluten is a family of proteins found in most cereals including wheat, rye, spelt, and barley. The two major proteins that makeup wheat protein are gliadin and glutenin. The gluten proteins when mixed with water, form cross-links which give it a glue-like consistency.

Celiac Disease

In people with celiac disease, gliadin is a powerful trigger of zonulin release. Zonulin increases intestinal permeability by opening the tight junctions in the epithelial lining, and in people with celiac disease, an auto-immune response follows.  This is a serious condition, and full-blown celiac disease is associated with complete atrophy of the villi which line the small intestine and absorb your nutrients. If you suspect celiac disease, particularly if you have a family history of celiac disease, please speak to your GP about testing.

Non-Celiac Gluten Sensitivity

Whilst increased intestinal permeability in response to dietary gluten is most severe in those with celiac disease, zonulin, a marker for intestinal permeability, is also increased in people with what is called non-celiac gluten sensitivity (NCGS) and also irritable bowel syndrome with diarrhea.

NCGS is a term applied to people who experience symptoms in response to consumed to gluten consumption but do not have celiac disease. They may feel gastro-intestinal discomfort, fatigue or neurological symptoms. These people tend to improve on a gluten-free diet. Unfortunately, these people can be mocked for avoiding wheat and told that it’s all in their head.

But researchers have found that people with NCGS have increased intestinal permeability compared to healthy subjects. This should not be surprising as we know gliadin increases the release of zonulin, which can affect tight junctions. The opening of these tight junctions, our gateways. allows macromolecules to come into contact with our immune system and our bloodstream and explains why the group with NCGS also had a systemic immune activation on eating gluten.

Gluten increases Intestinal Permeability in All Human Tissue

In a 2015 study, researchers found tissue taken from the duodenum of humans became permeable, and there was increased inflammation when exposed to gliadin (i.e. leaky gut). As this study is in tissue taken from people rather than directly in people themselves, we have to be careful extrapolating the results. However, this backs up the experiences of many people .. they feel better when they don’t consume gluten.

In people with gluten sensitivity and NCGS, the damage did not clear after 36 hours, and what is most surprising, is that after five hours the tissue taken from ‘healthy’ people without celiac of NCGS, still had increased permeability.

Now, the epithelial lining of the small intestine is made up of the fastest growing cells in the body, creating a new lining every 3 to 7 days, and the gut lining would heal itself after exposure to gluten. But, if you have toast for breakfast, a sandwich for lunch, and pasta for dinner, it is never getting a chance to heal. Remember, I’m talking about people who aren’t celiac or don’t have NCGS here. If you consume gluten for breakfast, lunch, and dinner, your gut lining never has a chance to repair and you leaky gut will develop.

Researchers refer to this as the loss of oral tolerance. Now, your body can not deal with the toxins you are exposed to, and it may also start reacting to foods you didn’t react to both, as your immune system fights to defend itself. You have pathogenic intestinal permeability or a leaky gut and this can lead to inflammation in the body and autoimmunity.

Although lab tests do exist to look at your sensitivity to gluten, it’s widely accepted that an elimination diet is the best way to test for gluten intolerance. If you have a chronic health condition, it may be a good idea to remove gluten from your diet and see if that is of benefit.

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