What happens in untreated coeliac disease?

When someone with coeliac disease eats gluten, the immune system reacts by damaging the lining of the gut.

The part of the gut that is affected in coeliac disease is the small intestine - which is below the stomach, and above the large intestine (colon).



In a healthy gut there are tiny, finger-like projections called 'villi' that allow the body to absorb nutrients from the food we eat into the blood.

This picture shows the villi of a healthy gut:



In untreated coeliac disease, these villi become inflamed and flattened. In some cases, they can even disappear.

Typical flattening of the villi in coeliac disease is called 'villous atrophy'. 

When the gut lining is damaged in this way, it means the body can't absorb all the nutrients from food properly. This process is called 'malabsorption'.

This picture shows the damage to the villi in someone with untreated coeliac disease:

The flattening of the gut villi and the malabsorption of nutrients causes many of the symptoms of coeliac disease and contributes to the health risks associated with coeliac disease such as anaemia and osteoporosis.

The abnormal immune response can affect other parts of the body, causing for example the skin rash dermatitis herpetiformis (DH).