Gluten

Doctors from the Royal Hallamshire Hospital, Sheffield published an article in this month’s edition of the British Medical Journal on the subject of gluten sensitivity, and whether it actually exists, in the absence of coeliac disease [1].

What is gluten?

Gluten is the molecule formed by the bonding of two proteins, glutenin and gliadin in the endosperm of cereal seeds such as wheat. The endosperm comprises the majority of the seed and is the initial source of energy the seed utilises when it germinates. Gluten is limited to grasses, although there are a wide range of similar protein composites in other plant seeds.

Man cannot live on bread alone?

Man cannot live on bread alone?

What is coeliac disease?

Coeliac disease is an autoimmune disease that affects the small intestine and is characterised by symptoms such as diarrhoea and fatigue.  The modification of the gluten proteins by the enzyme tissue transglutaminase (tTg) factors in the condition. Upon biopsy of the small intestine the defining sign is a marked change in the villi (small hairs) that line the inner surface of the gut (villous atrophy).  As these hairs vastly increase the surface area of the gut epithelium, reduction in them causes a reduction in the efficiency of uptake of nutrients from food.

Wheat Allergy

Coeliac disease is not to be confused with wheat allergy, which is a much rarer condition involving immunoglobulin E (IgE) mediated allergy to wheat seed storage proteins, including gluten, but also including albumins and globulins.

But what of those who claim to suffer from gluten-like abdominal symptoms, yet display normal tissue on biopsy? Do such individuals, as the paper’s authors suggest, belong to a “no man’s land”, with clinicians unsure how to treat them? There might well be a significant proportion of the population who fall into this category.  For example, in one study conducted in Scandinavia in 2000, of 94 adults complaining of abdominal problems after ingestion of cereals only 9% were found to have coeliac disease (as evidenced by villous atrophy). Of the remaining patients, all were negative for tTG antibodies, whereas 40% produced gliadin antibodies [2].

New evidence…

The authors cite a soon to be published study in which dietary trials on a much larger group of patients (n=920) with abdominal symptoms were conducted.  In the words of the authors:

“… a third of patients (n=276) showed clinical and statistically significant sensitivity to wheat and not placebo, with worsening abdominal pain, bloating, and stool consistency. The evidence therefore suggests that, even in the absence of coeliac disease, gluten based products can induce abdominal symptoms which may present as irritable bowel syndrome.”

As a result of this confusion, as of this year there is now a simplified nomenclature for the range of conditions [3]:

  • coeliac disease
  • wheat allergy
  • non-coeliac gluten sensitivity (this is potentially our 40% of those not displaying villous atrophy in the above study)

Gluten: a lone wolf?

Yet gluten is not the only possible culprit for these bowel issues when consuming cereals. Wheat contains a number of other molecules which are implicated in the irritation of the bowel – carbohydrates such as fermentable fructans for example, or sugars such as sorbitol and mannitol (part of a family of short-chain carbohydrates known collectively as FODMAPs).

So what should I eat…..?

If 40% of those in the Scandinavian trial suffered from non-coeliac gluten sensitivity, then it’s not an unreasonable idea to try eliminating gluten from your diet if you too suffer from similar symptoms.  This is difficult unless you are prepared to make some serious changes (giving up bread and pasta for example). However, like all things, stick with it and you might be very pleasantly surprised by how quickly your symptoms clear up.

Mine did!

References:

[1]. Aziz I, et al.: Does gluten sensitivity in the absence of coeliac disease exist? BMJ 2012; 345:e7907

[2]. Kaukinen K et al.: Intolerance to cereals is not specific for coeliac disease. Scand J Gastroenterol. 2000 Sep;35(9):942-6.

[3]. Sapone A, et al.: Spectrum of gluten-related disorders: consensus on new nomenclature and classification. BMC Med. 2012 Feb 10:13.