What causes coeliac disease?
Gluten and a substance related to gluten called gliadin are heavy proteins. They are found particularly in wheat and rye and to a lesser extent in barley and oats. These proteins are harmful to people who have coeliac disease. The exact mechanism for this effect is not known, but two alternative theories have been proposed to explain how this harm comes about: the toxic theory and the immune theory. According to the toxic theory, people with coeliac disease lack a particular enzyme which is normally found on the mucous membranes (mucosa) which line the small intestine. The function of this enzyme is to break gluten and gliadin down into smaller particles which are then able to pass through the wall of the intestine into the bloodstream. So, according to this theory, if a person with coeliac disease eats food containing gluten and gliadin, the lack of this enzyme will lead to an accumulation of gluten and gliadin on the mucous membranes of the small intestine. It is suggested that this