Coeliac Disease: What You Need to Know

The Autoimmune Mechanism

Coeliac disease is an autoimmune condition: your immune system attacks your own small intestine when you eat gluten. This is different from a food allergy, where the immune system reacts to a harmless substance as if it were dangerous. In coeliac disease, the immune system genuinely damages tissue.

When you consume gluten, your body's T cells identify gliadin (the main gluten protein) as a threat. They trigger an inflammatory response that damages the villi: tiny finger-like projections that absorb nutrients in your small intestine. Over time, repeated exposure can flatten these villi, leading to malabsorption of iron, calcium, B12, and other nutrients.

Genetic Component

Coeliac disease requires two genetic factors: the HLA-DQ2 or HLA-DQ8 gene variant, and additional genetic factors that increase risk. About 30-40% of the population carries HLA-DQ2 or DQ8, but only 1-3% develop coeliac disease. This means genetics load the gun, but something else pulls the trigger. Researchers suspect viral infections, gut bacteria, and timing of gluten introduction in infancy play a role.

If your parent or sibling has coeliac disease, you have a higher risk. Genetic testing can identify if you carry the risk genes, but testing positive doesn't mean you'll develop the disease. Blood tests for antibodies are more useful for diagnosis.

Classic vs Atypical Symptoms

Classic coeliac disease presents with diarrhoea, abdominal pain, bloating, and weight loss. This is what many people expect. However, about 30% of people have atypical symptoms: anaemia (from iron malabsorption), fatigue, bone pain, headaches, depression, or infertility. Some people have no gastrointestinal symptoms at all, only silent intestinal damage detected on biopsy. This is why coeliac disease is called 'the great imitator' and why diagnosis is often delayed.

Diagnosis: The Critical Step

Diagnosis requires two steps: serology (blood test) and endoscopic biopsy. The blood test checks for tissue transglutaminase (tTG) antibodies. If positive, an endoscopy biopsies the small intestine to confirm villous atrophy. Crucially, you must be eating gluten when tested. A gluten-free diet before diagnosis will give false-negative results. If you suspect coeliac disease, stay on your normal diet until you've been tested. After diagnosis, you can start a gluten-free diet immediately.

The Only Treatment: Strict Gluten Avoidance

There is no medication for coeliac disease (yet). The only treatment is a lifelong, strict gluten-free diet. Even tiny amounts of gluten (less than 20ppm) can trigger an immune response. Most people's intestines heal within weeks of starting a gluten-free diet, though complete healing can take months to years. You'll notice symptom improvement within days or weeks.

Long-Term Complications if Untreated

Untreated coeliac disease leads to serious complications: osteoporosis (from calcium and vitamin D malabsorption), anaemia, infertility, miscarriage, neurological problems, dermatitis herpetiformis (an itchy skin rash), and increased risk of intestinal lymphoma. Some of these complications are reversible with a gluten-free diet, but others (like permanent neurological damage) may not be. Early diagnosis is crucial.

Life Expectancy and Quality of Life

With a strict gluten-free diet, people with coeliac disease have a normal life expectancy. Quality of life improves dramatically once diagnosis is made and you understand how to manage it. The challenge is the learning curve: identifying hidden gluten sources, managing cross-contamination, eating out safely, and dealing with the social aspects of dietary restriction. Most people adjust within months and live normally.

Sources

FSANZ, Coeliac Australia, Celiac Disease Foundation, FDA, Beyond Celiac