The market for gluten-free products has exploded over the last ten years to reach several billion euros in Europe. Millions of people have voluntarily adopted a gluten-free diet, convinced that it improves their health, energy or digestion. However, the scientific question is much more nuanced: for whom is the avoidance of gluten medically necessary? For whom is it useless, or even potentially counterproductive? And what is gluten, really? It is necessary to rigorously take stock of this subject which concentrates as many beliefs as controversies.
1. What is gluten?
Gluten is a complex of proteins - mainly gliadin and glutenin - present in the endosperm of the seeds of certain cereals: wheat (and its varieties: spelt, kamut, triticale), barley and rye. Gluten is not present in rice, corn, quinoa, buckwheat, millet, sorghum, nor in legumes or potatoes.
Gluten plays an essential technological role in breadmaking: it is what gives viscoelasticity to the dough and allows the bread to rise. Gluten-free, the bread is dense and crumbly - a fact confirmed by anyone who has tried making bread with rice flour alone.
Gluten has been present in our diet since agriculture developed around 10,000 years ago. Its modern varieties have been selected for their higher gluten content, which constitutes one of the hypotheses put forward to explain the increase in gluten-related pathologies in recent decades.
| Pathology | Mechanism | Prevalence | Support |
|---|---|---|---|
| Celiac disease | Autoimmune reaction to gliadin. Destruction of intestinal villi. Diagnosis by serology (anti-tTG antibodies) and duodenal biopsy. | 1% of the world population. Underdiagnosed: only 20 to 30% of cases would be identified. | Strict and definitive avoidance of gluten. Only treatment available. Less exposure can restart the immune reaction. |
| Wheat allergy | IgE-mediated allergic reaction to wheat proteins (not just gluten). May cause anaphylaxis. | Rare in adults. More common in children, often transient. | Eviction of wheat. Not necessarily all cereals with gluten. Allergy monitoring essential. |
| Non-celiac gluten sensitivity (NCGS) | Mechanism not fully understood. No autoimmune or allergic reaction identified. Improvement in symptoms when avoiding gluten. | Estimated between 0.5 and 13% depending on the studies, but definition and diagnosis still debated in the scientific community. | No valid diagnostic biomarker. Diagnosis of exclusion after elimination of celiac disease and wheat allergy. |
2. The three medically established situations
Science clearly distinguishes three distinct clinical entities linked to gluten, which it is important not to confuse:
3. Non-celiac gluten sensitivity: the scientific debate
Non-celiac gluten sensitivity (NCGS) is the most controversial entity. It manifests itself by digestive symptoms (bloating, abdominal pain, diarrhea or constipation) and extra-digestive symptoms (fatigue, headaches, mental fog) which improve with the avoidance of gluten, without the biological markers of celiac disease.
The major scientific problem is the difficulty in distinguishing a real effect of gluten from a FODMAP effect (Fermentable Oligosaccharides Disaccharides Monosaccharides And Polyols). FODMAPs are fermentable carbohydrates found in wheat and which, in people suffering from irritable bowel syndrome, can cause exactly the same symptoms as those attributed to gluten.A study published in Gastroenterology (2013) by Gibson's team showed that under double-blind conditions, people who declared themselves sensitive to gluten had the same symptoms with gluten and without gluten, but improved their condition on a low FODMAP diet. This suggests that it is often wheat as a whole, and not gluten specifically, that is the problem.
This distinction is important: it directs towards different dietary management and avoids unnecessary restriction of gluten in people who could simply benefit from a reduction in FODMAPs.
4. Gluten-free for everyone: what the science says
For people without celiac disease, wheat allergy, or proven NCGS, current scientific data does not support the benefit of a gluten-free diet. Here's what the studies show:
- ●No metabolic benefit demonstrated: several randomized, double-blind studies have not shown improvement in blood sugar, weight, body composition or inflammatory markers in healthy subjects following a gluten-free diet compared to a gluten-containing diet.
- ●Risk of nutritional deficits: industrial gluten-free products are often less rich in fiber, B vitamins and iron than their gluten equivalents. A review published in Nutrients (2017) documented deficiencies in fiber, iron, calcium, zinc and B vitamins in people following a strict gluten-free diet without medical indication.
- ●High cost without justification: gluten-free products are on average 2 to 3 times more expensive than their traditional equivalents. For a person without medical indications, it is an investment with no return on health.
- ●Often lower nutritional quality: to reproduce the texture and lightness of gluten, manufacturers often use more starch, sugar, saturated fats and additives. A gluten-free cookie is no healthier than a regular cookie.
5. Whole grains with gluten: beneficial foods
It is important to remember that whole grains containing gluten - whole grain bread, whole grain pasta, oatmeal, barley, rye - are among the best documented foods for the prevention of chronic diseases. The meta-analysis published in The Lancet (2019) by Reynolds et al. showed that high intakes of whole grains were associated with a significant reduction in cardiovascular risk, type 2 diabetes and colorectal cancer.
Eliminating them without medical indication deprives you of these benefits. The essential distinction is between whole grains with gluten (beneficial) and products processed from white flour with gluten (to be limited) - a confusion often maintained in discussions around gluten.
6. What should I do if I think I have gluten sensitivity?
If I have digestive or extra-digestive symptoms that lead me to suspect gluten sensitivity, here is the approach recommended by learned gastroenterology societies:
- ●I consult my doctor before eliminating gluten: the diagnosis of celiac disease requires a blood test with measurement of anti-transglutaminase antibodies, carried out before any elimination of gluten. If I eliminate gluten before the assessment, the antibodies become negative and the diagnosis becomes impossible.
- ●I carried out the recommended biological assessment: CBC, ferritin, vitamins B12 and B9, calcium, thyroid TSH. Celiac disease often causes multiple deficiencies that must be evaluated and corrected.
- ●If celiac disease is excluded, I explore the FODMAP track with a dietician: a low FODMAP diet under professional supervision often helps resolve digestive symptoms attributed to gluten.
- ●If NCGS is confirmed by a rigorous diagnosis of exclusion, the avoidance of gluten is then justified and must be maintained with dietary monitoring to avoid deficiencies.
💡 tips to remember
- Gluten-free is medically essential for 3 situations: celiac disease (1% of the population), wheat allergy and proven non-celiac gluten sensitivity. For others, no scientifically proven benefit.
- I never eliminate gluten before my blood test: the anti-tTG antibodies which diagnose celiac disease quickly become negative without gluten, making the diagnosis impossible.
- Digestive symptoms attributed to gluten are often due to FODMAPs in wheat, not gluten itself. Support from a dietician can resolve the problem without eliminating gluten.
- Industrial gluten-free products are not healthier: often richer in sugars, starches and additives, less rich in fiber and B vitamins. No confusion between gluten-free and healthy.
- Whole grains with gluten (whole grain bread, oatmeal, barley, rye) are among the best-documented foods for the prevention of chronic diseases. Eliminating them without a medical reason is counterproductive.
- If I suspect sensitivity, I consult my doctor: he is the one who coordinates the assessment, not me who self-diagnoses and removes gluten on my own.
