What is gluten?

Gluten is a storage protein which can primarly be found in wheat, but wheat is not the only one that celiacs need to avoid. Part of gluten which is the most interesting for celiac disease is called gliadin, in rye it is seaclin and in barley hordein. Even though rye and barley proteins are not glutenous, they have the same toxic effect on celiacs and that is why we classify them into the same gluten family. In short, it means that also rye and barley are also on the forbidden list for celiacs. Spelt, kamut and triticale come from the same grass gluten family and have to be avoided as well. Oats comes from the different goup, similar to rice, but is very often contaminated with gluten because of its close contact with wheat during cultivation, storage and proccessing.
Gluten is also very present in wheat products, such seitan (pure gluten) and couscous (crushed durum wheat).