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Understanding coeliac disease
Coeliac disease is an autoimmune condition. When someone with coeliac disease eats gluten, their immune system reacts and damages the lining of the small bowel. This can reduce the absorption of energy and nutrients.
How common is coeliac disease?
Coeliac disease affects around 1 in 100 people in the UK. However, only about 36% of people with the condition are thought to have received a diagnosis, meaning many may be living with unexplained symptoms. The likelihood rises to approximately 1 in 10 when a parent, sibling or child has coeliac disease.
What is villous atrophy?
The healthy small bowel is lined with millions of tiny finger-like projections called villi. They greatly increase the surface area available to absorb nutrients from food.
In untreated coeliac disease, the immune reaction to gluten can shorten and flatten the villi. This is called villous atrophy. The reduced surface area makes absorption less effective and can contribute to deficiencies—including iron, folate, vitamin B12, calcium and vitamin D—as well as fatigue, weight loss and other symptoms.
Gluten is a protein found in wheat, barley and rye. Coeliac disease is different from a wheat allergy and from non-coeliac gluten sensitivity.
Symptoms vary
Possible symptoms include diarrhoea, constipation, abdominal pain, bloating, fatigue, mouth ulcers, hair loss, unplanned weight loss and iron, vitamin B12 or folate deficiency. Some people have few digestive symptoms. An itchy blistering skin condition called dermatitis herpetiformis can also be associated with coeliac disease.
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Testing and diagnosis
Speak to your GP if you have persistent symptoms, unexplained nutritional deficiencies or a close relative with coeliac disease. Testing usually begins with specific blood tests. Adults with positive blood results are normally referred to a gastrointestinal specialist, who will advise on confirmation of the diagnosis.
What does the blood test measure?
The usual first-line blood tests are tissue transglutaminase IgA (tTG-IgA) and total IgA.
- tTG-IgA looks for IgA antibodies directed against tissue transglutaminase. These antibodies are often raised when coeliac disease is active and the person is eating gluten.
- Total IgA checks whether your body produces enough IgA for the tTG-IgA result to be reliable. IgA deficiency can produce a falsely reassuring tTG-IgA result.
If tTG-IgA is weakly positive, the laboratory may check endomysial IgA antibodies (EMA-IgA). If total IgA is low, IgG-based tests—such as tTG-IgG, EMA-IgG or deamidated gliadin peptide IgG (DGP-IgG)—may be used instead.
The result must be interpreted alongside your symptoms, gluten intake and medical history. A negative result does not always exclude coeliac disease when clinical suspicion remains, and a positive result in an adult usually leads to specialist assessment and further confirmation.
Why might a gastroscopy be recommended?
For adults, a gastroenterology specialist may recommend a gastroscopy—also called an upper gastrointestinal endoscopy—to confirm or exclude coeliac disease. A thin flexible camera is passed through the mouth, beyond the stomach and into the first part of the small bowel.
During the procedure, several tiny tissue samples called biopsies are usually taken from the duodenum. These are examined under a microscope for changes associated with coeliac disease, including inflammation and villous atrophy. The biopsies help the specialist confirm the diagnosis, assess the degree of damage and consider other explanations for symptoms.
If you have already reduced or stopped gluten, tell your healthcare professional. Do not restart it without discussing how testing should be managed, particularly if previous reactions were severe.
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Starting a gluten-free diet
Once coeliac disease is confirmed, the treatment is a strict gluten-free diet for life. Even small amounts of gluten can cause intestinal damage, including when you do not notice immediate symptoms.
Begin with foods that are naturally gluten-free and familiar to you. These can include:
- fruit and vegetables;
- potatoes, rice, maize, quinoa and buckwheat;
- plain meat, fish, eggs, beans, lentils and pulses;
- milk, yoghurt and cheese where tolerated;
- nuts, seeds, oils and suitable spreads.
Specially manufactured gluten-free bread, pasta, flour, crackers and cereals can provide useful alternatives. A gluten-free diet can still be varied, enjoyable and nutritionally balanced.
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Reading labels and choosing food
UK food labels must emphasise cereals containing gluten when they are deliberately used as ingredients. Check every label because recipes and manufacturing processes can change.
Look for
Wheat, barley, rye and non-gluten-free oats in the ingredients list. Also check advisory statements about possible cross-contamination.
“Gluten-free”
Foods labelled gluten-free must meet the legal gluten limit and are suitable for people with coeliac disease.
Not every safe food needs a gluten-free label. Many foods are naturally gluten-free. Learning both routes can prevent the diet becoming unnecessarily restrictive or expensive.
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Preventing cross-contamination
Cross-contamination happens when gluten-free food comes into contact with crumbs, flour, cooking water, utensils, surfaces or equipment used for gluten-containing food.
- Clean hands, preparation areas and equipment before preparing gluten-free food.
- Use a separate toaster or toaster bags.
- Keep gluten-free spreads and condiments free from crumbs—separate jars can help.
- Use clean cooking water, oil and utensils.
- Store gluten-free ingredients separately and clearly label them.
- When eating out, explain that the meal is for coeliac disease and ask how cross-contamination is prevented.
You do not necessarily need a completely gluten-free household. What matters is having reliable routines that keep your food safe.
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What about oats?
Most people with coeliac disease can tolerate oats, but only oats specifically labelled gluten-free are suitable. Standard oats are often contaminated with wheat, barley or rye during growing and processing.
Oats contain a similar protein called avenin. A small number of people remain sensitive even to gluten-free oats. If symptoms continue or return after introducing them, discuss this with your dietitian or medical team.
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Nutritional recovery
As the small bowel heals, absorption and symptoms often improve. Recovery takes time and differs between individuals.
Possible areas to monitor
Gluten-free products are not automatically nutritionally superior. Some contain less fibre, iron or B vitamins and may contain more fat, sugar or salt than their standard equivalents. Include a range of naturally gluten-free foods and choose fortified products where useful.
If you were underweight or nutritionally deficient at diagnosis, you may need personalised advice and short-term supplements based on clinical assessment and blood results.
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Looking after your bones
People with coeliac disease can have reduced bone mineral density, particularly when the condition has been undiagnosed or untreated. Villous atrophy can reduce the absorption of calcium and vitamin D, which are important for building and maintaining strong bones.
Osteopenia
Bone density is lower than expected, but the reduction is not as severe as osteoporosis.
Osteoporosis
Bones become less dense and more fragile, increasing the risk of fractures.
When might a bone scan be considered?
A DEXA scan is a short, low-dose X-ray test that measures bone mineral density. Your GP or specialist may assess whether one is indicated—for example, when there are concerns about low bone density, fractures, prolonged malabsorption or other osteoporosis risk factors. NICE recommends considering the need for DEXA scanning when concerns arise during follow-up; it is not automatically required in exactly the same way for every person.
Calcium and vitamin D
Following a strict gluten-free diet supports intestinal healing and improved nutrient absorption. Include suitable sources of calcium and ensure vitamin D needs are considered. The British Dietetic Association calcium guide explains calcium requirements at different life stages and lists useful food and drink sources.
Exercise supports bone strength
Regular weight-bearing activity and resistance exercise help maintain bone and muscle strength. Depending on your health and ability, this might include brisk walking, stair climbing, dancing, resistance bands, body-weight exercises or weights. Balance exercises can also reduce the risk of falls.
Build activity gradually and choose exercise that is safe for you. Seek advice from a healthcare or exercise professional if you have osteoporosis, a previous fracture, significant pain or another condition that affects which movements are suitable.
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Follow-up and annual review
NICE recommends an annual review for people with coeliac disease. This should include your weight, symptoms and how you are managing the gluten-free diet, with consideration of specialist dietetic advice.
Your GP or specialist may also consider blood tests, bone-health assessment and whether any complications or associated conditions require further review.
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If symptoms continue
Do not assume ongoing symptoms mean the gluten-free diet has failed. Arrange a review with your GP, gastroenterology team or dietitian.
Possible reasons include accidental gluten exposure, another condition such as lactose intolerance or IBS, slow recovery, or—less commonly—a complication of coeliac disease. Your original diagnosis and diet may need to be reviewed before further investigation.
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How a dietitian can help with coeliac disease
A coeliac dietitian can teach you how to follow a strict lifelong gluten-free diet, interpret labels, prevent cross-contamination at home and make safer choices when eating out or travelling. They can also help replace gluten-containing staples without losing fibre, iron, calcium, folate and other important nutrients.
Dietetic review can address weight change, anaemia, low vitamin or mineral levels and bone-health needs. If symptoms or blood tests do not improve, a dietitian can look for hidden gluten exposure, nutritional deficiencies and possible overlapping conditions, while liaising with the medical team when further investigation is required.
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