Coeliac disease explained

What coeliac disease is

The small intestine is lined with tiny finger-like projections called villi that absorb nutrients from food. In coeliac disease, gluten triggers the immune system to damage and flatten these villi, a process called villous atrophy. With fewer villi, the body cannot absorb vitamins, minerals and energy properly, which explains many of the symptoms. Coeliac disease is autoimmune, meaning the body attacks its own tissue, and it has a strong genetic link, so it runs in families. It is more common in people with other autoimmune conditions, such as type 1 diabetes and thyroid disease. It can develop at any age, from childhood to later life, once gluten is part of the diet.

Recognising the symptoms

Coeliac disease can cause a wide range of symptoms, and some people have very few. Digestive problems are common, including bloating, tummy pain, diarrhoea, constipation and wind. Because nutrients are poorly absorbed, people may feel very tired, lose weight, or develop iron-deficiency anaemia. Other signs include mouth ulcers, headaches, and in children, poor growth or delayed puberty. Some people have an itchy, blistering skin rash called dermatitis herpetiformis. Symptoms are so varied that coeliac disease is often mistaken for irritable bowel syndrome or missed altogether. Anyone with ongoing unexplained tummy symptoms, tiredness or anaemia should ask their GP about testing, as diagnosis can bring real relief.

How coeliac disease is diagnosed

Diagnosis starts with a blood test that looks for particular antibodies the immune system makes in response to gluten. Crucially, you must keep eating gluten regularly before and during testing, otherwise the results can be falsely normal — so do not cut out gluten before being tested. If the blood test suggests coeliac disease, the GP refers you to a gut specialist, who usually confirms the diagnosis with a biopsy: small samples of the small intestine lining are taken during an endoscopy and examined for damage. Some children may be diagnosed without a biopsy under specialist guidance. Getting a firm diagnosis matters because a gluten-free diet is lifelong and needs proper support.

Managing coeliac disease with diet

The only treatment is a strict, lifelong gluten-free diet. This means avoiding all foods containing wheat, barley and rye, including many breads, pastas, cereals, cakes and sauces. Even small amounts of gluten, or cross-contamination from shared toasters or utensils, can cause damage, so care is needed. Naturally gluten-free foods include fruit, vegetables, meat, fish, eggs, rice and potatoes, and there are many gluten-free substitutes available. Reading labels carefully becomes second nature. A dietitian's support is important to ensure the diet is balanced and nutritious. Once gluten is removed, the gut lining heals over months, symptoms improve and the risk of complications falls. Oats can be included only if certified gluten-free and tolerated.

Follow-up and long-term health

After diagnosis, the NHS offers regular follow-up, usually including an annual review. This checks that symptoms are controlled, that the diet is being followed and remains balanced, and that any nutrient deficiencies, such as iron, calcium or vitamin D, are corrected. Because untreated coeliac disease can weaken bones, some people have their bone health assessed. Close relatives may be offered testing, as the condition runs in families. Sticking to the gluten-free diet greatly reduces the risk of complications such as osteoporosis and, rarely, certain cancers. Support from Coeliac UK, dietitians and the GP makes managing the condition easier, and most people live full, healthy lives once well established on the diet.