Coeliac disease is an autoimmune condition. This is where the immune system, the body's defence against infection, mistakenly attacks healthy tissue.
In coeliac disease, the immune system mistakes substances found inside gluten as a threat to the body and attacks them.
This damages the surface of the small bowel (intestines), disrupting the body's ability to absorb nutrients from food.
It can cause a range of symptoms, including diarrhoea, abdominal pain and bloating.
Coeliac disease is caused by an adverse reaction to gluten, a dietary protein found in 3 types of cereal: