It used to be thought that a leaky gut was a myth dreamt up by practitioners of complementary medicine. But recently, research from Dr A Fasano in Boston, USA has shown that the gut wall can become permeable, and that gluten is particularly involved in this. This is leading to a better understanding of why sensitivity to gluten seems to be on the rise.

Dr Fasano was originally researching a vaccine for cholera, but he accidentally came across a protein, zonulin, which regulates the tight junctions in the gut wall. Too much zonulin makes the gut permeable. In people with a genetic susceptibility to coeliac disease, gluten increases the amount of zonulin produced(2). Gluten molecules can then get through the gut wall into the bloodstream where they may trigger an autoimmune reaction.

But along with the genetic susceptibility, some other trigger must be involved in developing coeliac disease. There is a genuine rise in numbers of people getting coeliac disease(4). What may be a contributing are imbalances in the gut microbiome(3). The bacteria that you have in your intestines can change your health both in positive and negative ways. It may also explain why some people with the genetic susceptibility to coeliac disease develop the condition while their siblings don’t.

We have a huge number of bacterial cells, mostly in our large intestines, with hundreds of different species, both beneficial and pathogenic (although even the pathogenic ones play their roles). Obviously, having more beneficial than pathogenic ones has positive benefits for our health. They are implicated in the development of coeliac disease or gluten sensitivity because they can influence the activity of genes. Our tolerance to gluten may be lost if the microflora alters. Bacteria can also influence weight gain – unbalanced bacteria can lead to obesity(5).

Many things can change the microbiome - stress, a bacterial or viral infection and taking antibiotics.  Diet can influence them – refined carbohydrates may cause less beneficial types of bacteria to predominate. Children living in Finland are five times more likely to develop coeliac disease than their neighbouring Russian counterparts. The Russian children have a much wider range of gut bacteria, including some things that we would think of as harmful such as helicobacter pylori, the bacterium that can cause stomach ulcers(3).

Many people with coeliac disease and NCGS still don’t feel fully well even on a gluten-free diet. This may be because their gut bacteria remains unbalanced. The gut microbiome has many roles from improving carbohydrate digestion to absorption of B vitamins, from lactose absorption to better immunity. The flora of coeliacs on a gluten-free diet is still different to the general population(1). Improving the balance of the bacteria both for coeliacs and those with non coeliac gluten sensitivity has the potential to repair the gut barrier and restore some immune tolerance.

References:
1) De Palma, G., Nadal, I., Collado, M. C., & Sanz, Y. (2009). Effects of a gluten-free diet on gut microbiota and immune function in healthy adult human subjects. British Journal of Nutrition, 102(08), 1154-1160.
2)Drago, S. Et al. (2006). Gliadin, zonulin and gut permeability: Effects on celiac and non-celiac intestinal mucosa and intestinal cell lines. Scandinavian journal of gastroenterology, 41(4), 408-419.
3) Kondrashova, A. Et al. (2008). Lower economic status and inferior hygienic environment may protect against celiac disease. Annals of medicine, 40(3), 223-231.
4) Rubio–Tapia, A. et al. (2009). Increased prevalence and mortality in undiagnosed celiac disease. Gastroenterology, 137(1), 88-93.
5) Shen, J., Obin, M. S., & Zhao, L. (2013). The gut microbiota, obesity and insulin resistance. Molecular aspects of medicine, 34(1), 39-58.