Gluten Intolerance or Coeliac Disease: How to Tell the Difference?
Bloating, pain, fatigue — is gluten to blame? Coeliac disease, intolerance or allergy: we untangle it all to help you understand your gut.
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Gluten: a common culprit — but not always for the same reasons
Gluten is one of the most talked-about topics in digestive health. Yet behind this single word lie very different realities: coeliac disease, gluten intolerance (or non-coeliac gluten sensitivity) and wheat allergy are three distinct conditions that are frequently confused with one another. Mixing them up can have real consequences for your health. Here is what the science actually says.
Coeliac disease: a serious autoimmune condition
Coeliac disease is a chronic autoimmune condition. When someone with the disease ingests gluten — the protein found in wheat, barley and rye — their immune system turns against the lining of their own intestine.
In practice, gluten activates T-lymphocytes that attack tissue transglutaminase, an enzyme present in the wall of the small intestine. Over time, the intestinal villi (the tiny structures responsible for absorbing nutrients) gradually waste away. This is known as villous atrophy.
The consequences are significant:
- Malabsorption of nutrients (iron, calcium, B vitamins, vitamin D…)
- Chronic diarrhoea, abdominal pain and bloating
- Severe fatigue, anaemia and growth delays in children
Coeliac disease affects roughly 1% of the global population, yet it remains widely underdiagnosed. Diagnosis relies on serology (measuring anti-transglutaminase antibodies) confirmed by an intestinal biopsy. The treatment? A strict, lifelong gluten-free diet — with no exceptions.
Gluten intolerance: a different reaction, but a real one
Gluten intolerance (also called non-coeliac gluten sensitivity, or NCGS) is a less clearly defined condition, though it is gaining increasing recognition within the medical community.
In this case, there is no autoimmune reaction and no villous atrophy visible on biopsy. The mechanism instead involves antigen-IgG complexes that promote low-grade inflammation in the intestine. This is often accompanied by increased intestinal permeability (the so-called leaky gut) and disruption of the gut microbiota.
Symptoms resemble those of coeliac disease — bloating, pain, diarrhoea, fatigue — but may also include extra-digestive manifestations such as joint pain or difficulty concentrating (the well-known brain fog).
Unlike coeliac disease, there is no validated standard test to diagnose gluten intolerance. IgG tests frequently marketed outside of medical settings remain controversial in terms of reliability. The recommended approach is a temporary elimination diet, carried out under medical supervision and only after coeliac disease and wheat allergy have been ruled out.
Allergy, intolerance, coeliac disease: a comparison
| Coeliac disease | Intolerance (NCGS) | Wheat allergy | |
|---|---|---|---|
| Mechanism | Autoimmune (IgA, T-lymphocytes) | IgG inflammation, leaky gut | IgE immune response |
| Intestinal damage | Yes (villous atrophy) | No | No |
| Anaphylactic risk | No | No | Yes |
| Diagnosis | Serology + biopsy | Clinical exclusion | Allergy testing |
| Treatment | Strict lifelong gluten-free diet | Partial or full elimination | Strict elimination |
Why self-diagnosis is risky
Cutting out gluten without consulting a doctor may seem harmless, but it raises two serious problems:
- Skewing the diagnosis: if you remove gluten before your tests, coeliac antibodies will come back negative — even if you genuinely have the disease.
- Missing a serious condition: untreated coeliac disease leads to severe nutritional deficiencies, bone loss and, in the long term, an increased risk of certain intestinal lymphomas.
If you suspect you are reacting to gluten, speak to your GP or a gastroenterologist first.
What you can do right now
A few practical steps to take while you wait for an appointment:
- Keep a food diary: record what you eat and any associated symptoms (timing, severity and type). Apps designed for gut tracking can be a helpful tool for this.
- Look out for ultra-processed foods high in hidden gluten: shop-bought bread, biscuits, sauces, processed meats… Regular consumption of these can worsen intestinal permeability.
- Do not eliminate gluten on your own before undergoing a medical assessment.
- In children, symptoms such as growth delays, anaemia or persistent diarrhoea warrant early screening for coeliac disease.
A final word
Gluten, coeliac disease, intolerance: these terms are often used interchangeably, and incorrectly so. Coeliac disease is a serious autoimmune condition requiring rigorous medical management. Gluten intolerance, meanwhile, remains a clinical reality that science is still working to fully understand — one that deserves to be taken seriously, without swinging to the other extreme of unnecessary, blanket elimination.
Your gut deserves a precise answer, not a guess. A proper medical assessment remains your best guide.