Coeliac Disease: Symptoms, Diagnosis and Gluten-Free Diet

Do you experience recurring bloating, diarrhoea, unexplained anaemia or abdominal discomfort after eating wheat-based foods? These symptoms can have several causes, but in some people they may indicate coeliac disease.

Coeliac disease, also spelled celiac disease, is a chronic autoimmune condition in which eating gluten triggers an immune reaction that damages the lining of the small intestine. This damage can interfere with the absorption of nutrients and may lead to symptoms affecting more than just the digestive system.

An important point: do not start a gluten-free diet before being tested for suspected coeliac disease. Avoiding gluten can affect blood-test results and intestinal findings, making the diagnosis more difficult.

What Is Coeliac Disease?

Coeliac disease develops when the immune system reacts abnormally to gluten in genetically susceptible individuals.

Gluten is a group of proteins found primarily in wheat, barley and rye. When a person with coeliac disease consumes gluten, the immune response can damage the small intestine’s lining.

The small intestine contains tiny finger-like projections called villi. These increase the surface area available for nutrient absorption.

In coeliac disease, the villi may become shortened or flattened. This can reduce the absorption of nutrients such as iron, folate, calcium and other essential vitamins and minerals.

Coeliac disease is not simply an intolerance to wheat, and it is not the same as a food allergy. It is an autoimmune disorder that requires accurate diagnosis and long-term management.

What Are the Symptoms of Coeliac Disease?

Symptoms vary considerably. Some people have prominent digestive symptoms, while others experience problems such as anaemia or fatigue without obvious diarrhoea.

Digestive symptoms

Common gastrointestinal symptoms include:

• Recurrent bloating and abdominal distension.
• Excessive gas.
• Chronic or recurrent diarrhoea.
• Abdominal pain or discomfort.
• Bulky or difficult-to-flush stools in some patients.
• Unintentional weight loss.
• Symptoms resembling irritable bowel syndrome.

Constipation can also occur. Therefore, the absence of diarrhoea does not rule out coeliac disease.

Symptoms outside the digestive system

Coeliac disease may also be associated with:

• Iron-deficiency anaemia.
• Persistent fatigue or weakness.
• Folate or vitamin deficiencies.
• Reduced bone density or osteoporosis.
• Recurrent mouth ulcers.
• Certain itchy skin rashes.
• Unexplained nutritional deficiencies.
• Poor growth in children.

Some patients have few noticeable symptoms despite intestinal damage.

If you have persistent unexplained anaemia, ongoing digestive symptoms or a nutritional deficiency, your doctor may consider testing for coeliac disease. NICE

Who Should Be Tested for Coeliac Disease?

Testing may be appropriate for people with:

• Persistent unexplained gastrointestinal symptoms.
• Unexplained iron-deficiency anaemia.
• Unintentional weight loss or nutritional deficiencies.
• A first-degree relative with coeliac disease.
• Type 1 diabetes or certain autoimmune conditions.
• Irritable bowel syndrome symptoms when coeliac disease has not been excluded.
• Persistently raised liver enzymes without an established cause.

These symptoms do not necessarily mean you have coeliac disease. They are reasons to discuss appropriate investigations with a healthcare professional.

Testing should be based on clinical assessment rather than symptoms alone. NICE

How Is Coeliac Disease Diagnosed?

Diagnosis usually involves blood tests and, in many adults, an upper gastrointestinal endoscopy with biopsies of the small intestine.

1. Blood tests

The initial investigation commonly includes:

Tissue transglutaminase IgA (tTG-IgA): This is a widely used first-line antibody test for coeliac disease.

Total IgA: This helps identify IgA deficiency, which can make an IgA-based coeliac test falsely reassuring.

If IgA deficiency is present, your doctor may recommend appropriate IgG-based antibody tests.

A positive antibody result requires interpretation in the context of symptoms, test levels and the diagnostic pathway used. It should not automatically be treated as a confirmed diagnosis without the necessary assessment.

2. Upper GI endoscopy and intestinal biopsy

In many adults, an upper GI endoscopy is used to collect small tissue samples from the duodenum, the first part of the small intestine.

A pathologist examines these samples for changes consistent with coeliac disease, including villous damage.

The procedure is performed when indicated and helps establish the diagnosis in many patients.

Some newer guidelines allow a specialist-led, no-biopsy pathway for selected adults who meet strict criteria. Whether this is appropriate depends on the individual, the diagnostic protocol and local clinical practice. Do not interpret an antibody result on your own or skip recommended investigations.

The 2026 British Society of Gastroenterology guideline provides updated recommendations for adult diagnosis and management.

3. Why you should not stop eating gluten before testing

Blood tests and intestinal biopsies look for changes associated with the immune response to gluten.

If you stop eating gluten before the diagnostic process is complete, antibody levels may fall and intestinal changes may improve. This can make results less reliable.

If you suspect coeliac disease, continue your usual gluten-containing diet until you have discussed testing with your doctor, unless you have been advised otherwise for a specific medical reason.

If you have already started a gluten-free diet, tell your gastroenterologist. A supervised gluten challenge or an alternative diagnostic approach may sometimes be considered. Do not reintroduce gluten on your own if you have previously had significant reactions or have concerns about doing so.

Is Coeliac Disease the Same as Gluten Intolerance?

No. Several conditions can cause symptoms associated with eating wheat or gluten, but they are different.

Condition	What happens?
Coeliac disease	An autoimmune reaction to gluten damages the small intestine.
Wheat allergy	The immune system produces an allergic reaction to wheat proteins, which can sometimes be severe.
Non-coeliac gluten sensitivity	A person experiences symptoms associated with gluten-containing foods without the diagnostic findings of coeliac disease or wheat allergy.

Symptoms alone cannot reliably distinguish these conditions.

Some people who believe they have gluten intolerance may have another cause of their symptoms, including IBS or sensitivity to fermentable carbohydrates in wheat.

Appropriate assessment can help prevent unnecessary dietary restrictions and ensure that coeliac disease is not missed.

What Is the Treatment for Coeliac Disease?

At present, the established treatment for confirmed coeliac disease is a strict, lifelong gluten-free diet.

Avoiding gluten allows the intestinal lining to recover in many patients and helps reduce the risk of complications associated with ongoing exposure.

Dietary management should ideally be guided by a registered dietitian or qualified nutrition professional familiar with coeliac disease.

Foods that contain gluten

Common sources include:

• Wheat and wheat flour.
• Atta and maida.
• Semolina or suji.
• Dalia made from wheat.
• Barley, also known as jau.
• Rye.
• Ordinary wheat-based bread, biscuits, cakes and many noodles.
• Foods containing gluten-containing flour, malt or other gluten-derived ingredients.

Read ingredient labels carefully, especially on packaged foods, sauces, snacks and processed products.

In India, wheat flour can be present in many everyday foods, including rotis, parathas, breads and some prepared snacks.

Naturally gluten-free foods

Many familiar foods can form part of a balanced gluten-free diet, including:

• Rice.
• Maize.
• Jowar and bajra.
• Pulses and lentils.
• Fresh fruits and vegetables.
• Eggs.
• Plain milk and suitable dairy products.
• Unprocessed meat and fish.
• Nuts and seeds.

However, a food that is naturally gluten-free can become contaminated during processing, storage or preparation.

For example, flour residue on shared equipment, contaminated packaged foods or cross-contact in a kitchen can expose someone with coeliac disease to gluten.

What about oats?

Oats are naturally different from wheat, barley and rye, but ordinary oats may be contaminated with gluten during cultivation or processing.

Some patients may be able to include appropriately certified gluten-free oats, depending on their individual tolerance and clinical advice.

Discuss this with your dietitian or treating doctor rather than assuming every oat product is suitable.

Can a Gluten-Free Diet Cause Nutritional Deficiencies?

A poorly planned gluten-free diet can be low in fibre, iron, folate and other nutrients.

This is particularly important because people with untreated coeliac disease may already have nutritional deficiencies due to reduced intestinal absorption.

A balanced gluten-free diet should include a variety of suitable whole grains, pulses, vegetables, fruits, protein sources and other nutrient-rich foods.

Your doctor may recommend blood tests to assess deficiencies and determine whether supplements are needed.

Avoid taking iron, vitamin D or other supplements indefinitely without establishing whether they are necessary.

What Happens If Coeliac Disease Is Left Untreated?

Continued gluten exposure in a person with coeliac disease can maintain intestinal inflammation and damage.

Potential consequences include:

• Persistent symptoms and impaired quality of life.
• Iron-deficiency anaemia.
• Vitamin and mineral deficiencies.
• Reduced bone density.
• Unintentional weight loss or malnutrition.
• Persistent intestinal damage.

Serious complications can occur in a small minority of patients, but individual risk varies. Accurate diagnosis, a strict gluten-free diet and appropriate follow-up help reduce the risks associated with untreated disease.

Does Coeliac Disease Require Lifelong Follow-Up?

Yes. People with confirmed coeliac disease benefit from ongoing clinical and nutritional review.

Follow-up may include:

• Reviewing digestive symptoms and dietary adherence.
• Assessing weight and nutritional status.
• Rechecking relevant blood tests.
• Correcting identified deficiencies.
• Evaluating persistent symptoms despite a gluten-free diet.
• Considering bone health and other investigations when indicated.

If symptoms continue despite following a gluten-free diet, do not assume that gluten exposure is the only possible explanation. Other conditions, accidental contamination, ongoing intestinal injury or additional digestive disorders may need assessment.

Current adult guidelines emphasize individualized follow-up and nutritional support.

Frequently Asked Questions About Coeliac Disease

1. What are the early symptoms of coeliac disease?

Early symptoms may include bloating, diarrhoea, abdominal discomfort, fatigue or unexplained anaemia. Some people have few digestive symptoms, so testing may be appropriate even without chronic diarrhoea.

2. Which blood test is used for coeliac disease?

The tTG-IgA antibody test, usually combined with total IgA measurement, is a common first-line investigation. Additional tests may be needed depending on the results and the patient’s clinical circumstances.

3. Can coeliac disease be diagnosed by a blood test alone?

Blood tests are important, but many adults need further assessment, often including duodenal biopsies. Selected adults may qualify for a specialist-led no-biopsy pathway under certain current guidelines.

4. Should I stop eating wheat before a coeliac test?

No—not before discussing the diagnostic process with your doctor. Removing gluten may cause false-negative or less informative results. If you have already stopped gluten, tell your gastroenterologist.

5. Is coeliac disease curable?

There is currently no established cure. A strict lifelong gluten-free diet is the standard treatment and allows many patients to improve clinically and recover intestinal health.

6. Can coeliac disease cause iron-deficiency anaemia?

Yes. Damage to the small intestine can impair nutrient absorption, and iron deficiency may be a presenting feature even when digestive symptoms are mild.

7. Can people with coeliac disease eat rice and millets?

Rice, jowar and bajra are naturally gluten-free. They can be suitable choices when uncontaminated, prepared safely and included as part of a nutritionally balanced diet.

8. Is gluten intolerance the same as coeliac disease?

No. Coeliac disease is an autoimmune condition that damages the small intestine. Wheat allergy and non-coeliac gluten sensitivity are different conditions and require different approaches.

9. Can coeliac disease affect the liver?

Some people with coeliac disease have raised liver enzymes, and coeliac disease may coexist with other liver conditions. Persistent unexplained liver-test abnormalities may be a reason to consider coeliac testing. Abnormal liver tests do not, by themselves, establish the diagnosis.

10. Which doctor should I consult for coeliac disease in Faridabad?

A gastroenterologist can assess symptoms, arrange appropriate blood tests and decide whether endoscopy with intestinal biopsies or other investigations are needed. A qualified dietitian can help plan a nutritionally adequate gluten-free diet after diagnosis.

Final Takeaway

Coeliac disease is more than a digestive intolerance. It is an autoimmune condition that can affect nutrient absorption and cause symptoms ranging from bloating and diarrhoea to anaemia and bone problems.

The most important step is to obtain an accurate diagnosis before eliminating gluten. Once coeliac disease is confirmed, a strict gluten-free diet and appropriate long-term follow-up are essential parts of management.

About the author

Dr Vishal Khurana is a gastroenterologist and liver specialist in Faridabad, Haryana.

Medical disclaimer: This article is for general educational purposes and does not replace individual medical advice. Medical review date: 20-10-2026