Causes - Coeliac disease

Coeliac disease is an autoimmune condition. An autoimmune condition is when your immune system makes a mistake and fights healthy cells in your body instead of bacteria or viruses.

What happens

In coeliac disease, your body's immune system has an abnormal reaction to gluten in your diet. Gluten is found in foods such as bread, pasta, cereals and biscuits.

Your immune system thinks that gluten is a threat to your body. Whenever it thinks your body is under threat, your immune system produces antibodies. This is to protect your body. Antibodies usually fight off bacteria and viruses.

But because your immune system has made a mistake, it starts to attack parts of your body that are healthy.

Damage to intestine

The antibodies cause your intestine to become red and swollen. They damage a part of your intestine that helps it to digest food.

The intestine surface is usually covered with millions of tiny tube-shaped growths. These are called villi. Villi increase the surface area of your gut and helps it to digest food.

With coeliac disease, the damage to the lining of the gut flattens the villi. This reduces their ability to help with digestion. Because of this, your intestine isn't able to digest the nutrients from your food. This causes the symptoms of coeliac disease.

Oats

Some people with coeliac disease may find that eating oats can trigger symptoms. This is because some oats may get contaminated by other grains during production.

Oats also contain a protein called avenin. This is like gluten. Most people with coeliac disease can safely eat avenin.

Increased risk

It's not known why people develop coeliac disease. It also isn't clear why some have mild symptoms while others have severe symptoms.

Family history, environmental factors and certain health conditions increase your risk of developing coeliac disease.

Family history

Coeliac disease often runs in families. Your chance of getting it is higher if you have a close relative with the condition. For example, a parent, brother or sister.

If you have a family history of coeliac disease, there's around a 10% risk you will develop it. If you have an identical twin with coeliac disease, there's a 75% chance you will develop it too.

Coeliac disease is linked to genetic changes to a group of genes that help your immune system develop. They may get passed down through a family.

But this genetic change is common in lots of people. This suggests that something else must trigger coeliac disease in certain people. It may get caused by environmental factors.

Environmental factors

You're more likely to get coeliac disease if you had a digestive infection in early childhood. For example, a rotavirus infection.

Gluten in your baby's diet, before they're 3 months old, increases the risk of coeliac disease.

Wait until your baby is at least 6 months old before giving them food with gluten in it.

Babies may develop coeliac disease if not breastfed when gluten is added to their diet.

Other health conditions

Other health conditions can increase your risk of developing coeliac disease.

These include:

• type 1 diabetes
• thyroid conditions
• ulcerative colitis – a digestive condition that causes inflammation of the colon (large bowel)
• neurological disorders (which affect the brain and nervous system) such as epilepsy
• Down's syndrome and Turner syndrome

It's unclear if these health conditions increase the risk of developing coeliac disease. Or if they and coeliac disease are caused by another condition.