Celiac disease is a disorder of the small intestine caused by a reaction to gliadin, a protein found in gluten. This means eating foods containing wheat is literally off the menu, with a gluten-free diet the only treatment.
The big problem with celiac disease is actually being diagnosed. Although common symptoms include weight loss, diarrhea, abdominal pain, bloating, chronic fatigue, and mouth ulcers, not everyone experiences these, or indeed any, symptoms.
About 1 in 100 people is estimated to have celiac disease, although not all of them have been diagnosed, obviously.
Once diagnosed, the only treatment at present is cutting gluten out of your diet altogether which, although annoying, is easy to come to terms with. And once done, the symptoms and risks of serious complications disappear or at least lessen considerably.
