Gluten and Gliadin: How the Allergies Differ
For most people, there is no necessity to distinguish between gluten and gliadin because all that is necessary is to avoid eating foods that contain one or the other. However, for people with multiple allergies, or for those who are managing a variety of conditions, it can be important to understand the two proteins that contribute to gluten-intolerance and coeliac disease. Working with the proteins separately in trials and studies is also a vital part of the research into what causes, and may eventually cure, this dietary intolerance.
What Is Gluten?The dictionary says that gluten is a cohesive, elastic protein left behind after starch is washed away from wheat flour. This shows that only wheat is considered to have true gluten, although many people have intolerances to other grain proteins, particularly rye and barley and to another food (which is actually a fruit) called buckwheat. Gluten is useful because it ‘glues’ itself together and glues other proteins to itself, for this reason it is used in many different foods to make the food ‘stick’ rather than fall apart.
Wheat gluten is made up of many different proteins which fall into two main groups: the gliadins and the glutenins which in turn break down into even smaller units, called polypeptides. One specific polypeptide is known to be particularly harmful to the gut function of people with coeliac disease. This polypeptide contains a set of amino acid sequences which are known by the name gliadin. This is important because the sequence of amino acids is very similar to patterns of amino acid found in rye and barley. The polypeptide chain that is like gliadin but found in rye is called secalin, and the one found in barley is called hordein but in practice they are all lumped together under the shorthand of gliadin.