Understanding gluten intolerance and managing it
« Gluten intolerance » is a term that in reality covers three very different situations: coeliac disease, an autoimmune disease that requires a strict, lifelong gluten-free diet; non-coeliac gluten sensitivity, a digestive disorder whose exact cause is still debated; and wheat allergy. The most important rule fits in one sentence: do not stop eating gluten before you have been tested, otherwise a diagnosis becomes impossible to make.
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This guide explains how to tell these three conditions apart, how diagnosis works according to the recommendations of France’s Haute Autorité de santé (HAS, the national health authority) published in July 2026, and how to eat gluten-free day to day without creating deficiencies.
Three conditions not to confuse
The HAS in fact recommends avoiding the expression « gluten intolerance », which causes confusion, and speaking of coeliac disease when that is what is involved. Here is what sets the three situations apart.
| Coeliac disease | Non-coeliac gluten sensitivity | Wheat allergy | |
|---|---|---|---|
| Mechanism | Autoimmune disease of the small intestine in genetically predisposed people | Functional digestive disorder, with no antibodies or damage to the intestine | Allergic reaction to various wheat proteins |
| Frequency | 0.8 to 1% of the population | Unknown, no reliable marker | About 0.4% worldwide, mainly in children |
| Diagnosis | Blood test (antibodies) then, most often, biopsies of the intestine | Clinical, after ruling out the other two | Allergy work-up |
| Complications | Yes, without a diet (deficiencies, osteoporosis, rare digestive cancers) | Not associated with the complications of coeliac disease | Sometimes severe reactions (anaphylaxis) |
| Diet | Strict gluten-free, for life | Reduction to adjust according to symptoms | Avoiding wheat |
Gluten itself is a group of proteins: the gliadins and glutenins of wheat, the secalins of rye and the hordeins of barley. Oats contain similar proteins, the avenins, but in smaller amounts and in a less immunogenic form, the HAS points out.
Coeliac disease: what happens in the intestine
In a person with coeliac disease, the immune system reacts to gliadin by producing autoantibodies, notably anti-transglutaminase antibodies. This reaction causes inflammation and atrophy of the villi of the small intestine, the folds that absorb nutrients. The result: the body absorbs protein, fat, iron, calcium, vitamin D and folate (vitamin B9) less well, explains the Assurance maladie (the French national health insurance body).
A common but under-diagnosed disease
The HAS estimates prevalence at between 0.8 and 1% of the general population, with an incidence that has been rising for several decades and a large share of cases undiagnosed. A worldwide meta-analysis of 96 studies (Singh, 2018) found 1.4% of people with positive antibodies and 0.7% of cases confirmed by biopsy, with a higher frequency in women than in men (0.6% against 0.4%) and in children than in adults.
The role of genetics
According to the Assurance maladie, 95% of people with coeliac disease carry the HLA-DQ2 and/or HLA-DQ8 genes. But these genes are common: about 20% of people carry them without ever developing the disease. The risk is about 10% in first-degree relatives of someone with the disease (father, mother, brothers, sisters, children). This is why a negative HLA typing makes the disease very unlikely, whereas a positive typing proves nothing.
Why more cases?
The reasons are still poorly understood. The HAS cites better screening, changes in the gut microbiota, which has become more inflammatory in industrialised countries, and a shorter dough kneading time, which could leave more undigested gluten fragments. On the other hand, recent work by INRAE (the French national research institute for agriculture, food and the environment) has ruled out the idea that the composition of wheat gluten proteins has changed.
Symptoms: often not where you expect them
The classic picture combines chronic diarrhoea, weight loss and deficiencies. But the HAS stresses that with age, atypical and symptom-free forms become the majority in adults. In adults, the Assurance maladie notes that the disease is often diagnosed several years after the first symptoms.
Digestive signs
- Chronic or intermittent diarrhoea, or sometimes, on the contrary, unexplained constipation.
- Abdominal pain, persistent bloating, flatulence.
- Nausea, vomiting, difficult digestion that lingers.
Signs outside the gut
- Prolonged fatigue, paleness linked to anaemia from a lack of iron or folate.
- Unexplained weight loss; in children, a drop off the growth curve or delayed puberty.
- Recurrent mouth ulcers, tooth enamel defects.
- Chronic joint pain, osteoporosis or unexplained fractures.
- Recurrent miscarriages, infertility.
- Neuropathy, migraines, balance problems.
Dermatitis herpetiformis deserves a separate mention. This rare autoimmune skin disease (1 to 5 people in 10,000) is almost always associated with coeliac disease. It appears as small, intensely itchy blisters, arranged symmetrically on the elbows, knees and buttocks, and mainly affects people aged 20 to 45.
Who should be tested?
The HAS recommends targeted screening rather than screening the whole population. In addition to the symptoms above and abnormal blood test results (iron or vitamin deficiency, unexplained raised transaminases), a test is recommended in several at-risk groups:
- first-degree relatives of a person with coeliac disease;
- type 1 diabetes, thyroiditis or autoimmune hepatitis;
- unexplained bone fragility;
- IgA deficiency;
- Down’s syndrome, Turner or Williams-Beuren syndromes;
- microscopic colitis, IgA nephropathy, recurrent pancreatitis of unknown cause.
The HAS also flags a lesser-known clue: an oral treatment that is hard to balance despite being taken regularly (thyroid hormones, anticoagulants), which may point to poor absorption.
Diagnosis, step by step
1. Keep eating gluten
This is the condition for reliable tests. The HAS recommends not starting a gluten-free diet before the diagnosis is confirmed, because it lowers antibodies and partly heals the intestine: tests then become falsely negative. If you have already stopped, the Assurance maladie advises reintroducing gluten, more than 3 g a day and preferably 8 to 10 g a day, for 6 to 8 weeks (which can be shortened to 2 weeks if it is poorly tolerated).
| Food | Amount providing about 3 g of gluten |
|---|---|
| Rusks (biscottes) | 3 rusks of 10 g |
| Sliced sandwich bread | 2 slices of 25 g |
| Baguette | 40 g, or 1/6 of a baguette |
| Petit-beurre-style biscuits | 5 biscuits |
| Pasta (dry weight) | 30 g |
| T55 flour (plain white flour) | 30 g |
2. A blood test
As a first step, the HAS recommends measuring anti-transglutaminase IgA together with total IgA. No other blood test is recommended at the outset. Measuring total IgA is used to spot an IgA deficiency, which would skew the result. If the antibodies are absent, the disease is unlikely.
3. Biopsies, in most cases
If the antibodies are positive, an upper digestive endoscopy allows at least 2 biopsies to be taken from the duodenal bulb and 4 from the second part of the duodenum. In adults it is done without general anaesthetic; in children, under general anaesthetic.
4. Sometimes without a biopsy
After the opinion of a gastroenterologist, the diagnosis can be made without a biopsy if several conditions are met: anti-transglutaminase IgA at least 10 times the upper limit of normal, confirmed on a second sample (with positive anti-endomysium antibodies in children), age under 45, no type 1 diabetes and no severe or atypical clinical signs. The European paediatric guidelines (ESPGHAN, 2020) apply the same threshold in children.
Non-coeliac gluten sensitivity: what we really know
Many people feel better without gluten without having coeliac disease. The HAS defines non-coeliac gluten sensitivity as a digestive disorder triggered by foods containing gluten, with no antibodies or damage to the intestine, and without the complications of coeliac disease. No marker can diagnose it with certainty.
Above all, the role of gluten itself has not been demonstrated. Other components of wheat are suspected: enzyme inhibitors (the ATIs) and FODMAPs, fermentable carbohydrates. Two studies illustrate this well:
- An analysis of 10 double-blind, placebo-controlled trials involving 1,312 adults found gluten-specific symptoms in only 16% of people who described themselves as sensitive (38 out of 231), and 40% of those reacted as much or more to the placebo (Molina-Infante, 2017).
- In a Norwegian double-blind trial of 59 people, fructans (FODMAPs found in wheat) caused more bloating than gluten, and symptom scores on gluten did not differ from those on placebo (Skodje, 2018).
To confirm this diagnosis, a group of experts (the Salerno criteria, 2015) proposes reintroducing 8 g of gluten a day, blinded against placebo, with at least a 30% change in symptoms between the two phases. If you have irritable bowel syndrome, our guide to the FODMAP diet explains an approach with better evidence behind it than cutting out gluten at random.
Wheat allergy
This is a food allergy like any other, targeting various wheat proteins and not just gluten. According to the HAS, it can be immediate (digestive and skin symptoms, sometimes respiratory ones, up to anaphylaxis) or delayed, with chronic digestive problems in infants and children. It can disappear during childhood. In teenagers and adults there is a particular form, exercise-induced wheat anaphylaxis: symptoms appear only if physical exercise follows eating wheat. Here it is wheat that you avoid; barley and rye are not necessarily involved, which only an allergist can determine.
The gluten-free diet in practice
For coeliac disease, the Assurance maladie points out that a gluten-free diet is the only effective treatment, that it must be strict, uninterrupted and lifelong, and that it has no side effects. The help of a dietitian is advised.
What contains gluten
- All varieties of wheat (durum wheat, spelt, kamut), barley, rye and their hybrids such as triticale.
- Bread, viennoiseries, pastries, pasta, biscuits, most breakfast cereals.
- Breaded or battered foods, flour-thickened sauces (béchamel, roux), packet soups, soy sauce and tamari.
- All beers and seitan, which is almost pure gluten.
Gluten also hides, according to the Assurance maladie, in charcuterie (cured and processed meats), icing sugar, ground pepper, spice blends and some medicines. Hence the importance of reading labels: our guide to decoding food labels helps you spot allergens, which must be highlighted in the ingredients list.
What the labels mean
| Wording on the packaging | Maximum gluten content | If you have coeliac disease |
|---|---|---|
| « Gluten-free » | Less than 20 mg per kg of finished product | Can be eaten |
| « Very low gluten » | 21 to 100 mg per kg | Not recommended |
| « Gluten-free » oats | Less than 20 mg per kg, supply chain protected from contamination | Can be eaten by over 95% of people with coeliac disease |
Why so much strictness for such small amounts? A randomised double-blind trial (Catassi, 2007) gave 49 well-treated adults with coeliac disease 0, 10 or 50 mg of gluten every day for 90 days. At 50 mg a day, which is about one thirtieth of a 25 g slice of sandwich bread according to the Assurance maladie table (our calculation), the intestinal lining deteriorated measurably; the authors conclude that you need to stay under 50 mg a day of « contamination » gluten.
What you can eat freely
Many foods are naturally gluten-free: fruit, vegetables, pulses, unprocessed meat and fish, eggs, plain dairy products, oils. For starchy foods, the Assurance maladie cites rice, maize, buckwheat and potatoes, to which can be added quinoa, millet and amaranth. Our guide to gluten-free flours and alternatives details how to use them in cooking.
Swapping without losing out
Manufactured gluten-free products are not perfect equivalents. The Ciqual table (the French national food composition database) lets you compare:
| Food (per 100 g) | Energy | Protein | Fibre |
|---|---|---|---|
| Wheat pasta, cooked | 167 kcal | 6.1 g | 2.2 g |
| Gluten-free pasta, cooked | 163 kcal | 3.09 g | 1 g |
| White bread (baguette, round loaf) | 287 kcal | 8.27 g | 2.7 g |
| Gluten-free bread, pre-packed | 249 kcal | 4.58 g | 9.9 g |
| Quinoa, cooked | 149 kcal | 4.66 g | 3.8 g |
| Brown rice, cooked | 187 kcal | 3.87 g | 2.1 g |
| Potato, boiled | 81 kcal | 1.8 g | 1.8 g |
| Polenta, cooked | 76.1 kcal | 1.38 g | 1.6 g |
Gluten-free pasta provides about half as much protein and fibre as wheat pasta. The pre-packed gluten-free bread in the Ciqual table is, by contrast, high in fibre, but recipes vary a great deal from one brand to another: compare the labels. To keep a good intake of fibre and protein, rely on whole starchy foods (quinoa, buckwheat, brown rice) and pulses rather than processed substitutes. A few ideas: a buckwheat and vegetable salad or complete buckwheat galettes (check that the buckwheat flour has no added wheat).
Reimbursement in coeliac disease
In France, the Assurance maladie (the national health insurance) reimburses 60% of the cost of gluten-free dietary foods for people whose coeliac disease has been confirmed by biopsy, once cover has been approved as a long-term condition (affection de longue durée). Reimbursement is capped at €45.73 a month for an adult and €33.54 for a child under 10. The claim can be made from the ameli app by scanning the products’ barcodes; you need to keep the till receipts for 24 months.
Deficiencies, follow-up and complications
Straight after diagnosis, it is sometimes necessary to correct an iron or vitamin D deficiency, the Assurance maladie stresses. Our guides to iron-rich foods and vitamin D help you spot the good sources, in agreement with your doctor.
With a well-followed diet, symptoms disappear within a few weeks and antibodies after about a year; the intestine heals over the longer term and bone density recovers. Without a diet, and after a long course, the disease exposes you to more deficiencies, osteoporosis, other autoimmune diseases (type 1 diabetes, thyroiditis), infertility (12% of patients according to the Assurance maladie) and, more rarely, digestive cancers (lymphoma, small-bowel adenocarcinoma). There are also rare refractory forms, which do not heal despite more than a year of strict diet. To protect your bones, see our guide to bone health.
Common myths
- « My test is negative, so I don’t have coeliac disease. » Not if you were already gluten-free at the time of the test: the result may be falsely negative.
- « A bit of gluten now and then doesn’t matter. » With coeliac disease, it does: 50 mg a day is enough to damage the lining in Catassi’s trial.
- « Oats are banned. » Pure oats, from a certified gluten-free supply chain, are suitable for over 95% of people with coeliac disease.
- « Modern wheat contains more toxic gluten. » The HAS reports that INRAE’s work has ruled out a change in the composition of gluten proteins.
- « If I feel better without gluten, gluten must be the cause. » Not necessarily: the FODMAPs in wheat and the nocebo effect explain a good share of cases.
Frequently asked questions
What is the difference between gluten intolerance and coeliac disease?
They are often used as synonyms, but the HAS prefers « coeliac disease » to avoid confusion with non-coeliac gluten sensitivity, which causes neither antibodies nor damage to the intestine.
Should you stop gluten before the blood test?
No, definitely not. Tests must be done while eating gluten. If you have already stopped, the Assurance maladie advises reintroducing it, ideally 8 to 10 g a day for 6 to 8 weeks.
Can coeliac disease be cured?
The disease is permanent, but a strict gluten-free diet makes the symptoms disappear, normalises antibodies in about a year and lets the intestine heal.
Should my children be tested?
First-degree relatives are among the at-risk groups for whom the HAS recommends a test: their risk is about 10%.
Is it worth eating gluten-free without having coeliac disease?
The recommendations cited here do not provide for a gluten-free diet without a diagnosis. And starting one before the tests makes it impossible to establish a possible coeliac disease: talk to your doctor first.
Which cereals can you eat?
Rice, maize, buckwheat, quinoa, millet, potatoes, and oats certified gluten-free in the great majority of cases.
This article is for information only and does not replace the advice of your doctor or a dietitian.
Our sources
- Haute Autorité de santé, Maladie cœliaque : diagnostic chez l’enfant et l’adulte, recommandation de bonne pratique, July 2026.
- Assurance maladie (ameli.fr), Maladie cœliaque : définition, causes et facteurs favorisants ; Symptômes, diagnostic et évolution ; Régime alimentaire sans gluten ; Remboursement des aliments sans gluten, consulted in 2026.
- Singh P. et al., Global prevalence of celiac disease: systematic review and meta-analysis, Clinical Gastroenterology and Hepatology, 2018, PMID 29551598.
- Husby S. et al., European Society Paediatric Gastroenterology, Hepatology and Nutrition guidelines for diagnosing coeliac disease 2020, Journal of Pediatric Gastroenterology and Nutrition, 2020, PMID 31568151.
- Catassi C. et al., A prospective, double-blind, placebo-controlled trial to establish a safe gluten threshold for patients with celiac disease, American Journal of Clinical Nutrition, 2007, PMID 17209192.
- Molina-Infante J., Carroccio A., Suspected nonceliac gluten sensitivity confirmed in few patients after gluten challenge in double-blind, placebo-controlled trials, Clinical Gastroenterology and Hepatology, 2017, PMID 27523634.
- Skodje G. I. et al., Fructan, rather than gluten, induces symptoms in patients with self-reported non-celiac gluten sensitivity, Gastroenterology, 2018, PMID 29102613.
- Catassi C. et al., Diagnosis of non-celiac gluten sensitivity (NCGS): the Salerno experts’ criteria, Nutrients, 2015, PMID 26096570.
- European Commission, Regulation (EC) No 41/2009 and Implementing Regulation (EU) No 828/2014 on the information on the absence or reduced presence of gluten.
- Regulation (EU) No 1169/2011 on the provision of food information to consumers (highlighting of allergens).
- Anses, Table de composition nutritionnelle des aliments Ciqual, 2025.
Read also
Food profiles: Rye, Barley, Oats
Recipes to try: Barley orzotto with mushrooms, Pearl barley and vegetable salad, Cretan salad (dakos)
