Many people claim to feel better when they stop gluten, even though they don't have celiac disease. Is this diet really effective for diabetes and inflammatory bowel disease? Does it improve joint disorders and cognitive abilities? Does it really help to slim down? Specialists answer us.
Gluten is not welcome? No, clearly, for some of the people who decided to oust him from their plate. What do they blame him for? To cause bloating, spasms, and transit disorders, but also headaches, fatigue, itching, joint pain ...
First described in 1978, what is now known as non-celiac gluten sensitivity (NCGS) has been the subject of scientific consensus in recent years. "Doctors define it as a clinical entity in which the ingestion of gluten leads to digestive and extra-digestive symptoms that regress under a gluten-free diet," explains Catherine Grand-Ravel, a researcher at INRA. But it is based neither on autoimmune mechanisms as in celiac disease nor on allergic mechanisms as in wheat allergy. Symptoms to describe it; but no diagnostic tool: what is this sensitivity? If eating gluten-free is vital for celiac patients, what about when you don't suffer from this disease?
Is a gluten-free diet more digestible?
It's possible. "Gluten proteins are rich in proline, an amino acid that makes them less accessible than others to enzymes in the digestive tract," explains Dr. Nadine Cerf-Bensussan, research director at Inserm. As a result, the digestion of gluten leaves small fragments. "In celiac patients and in those allergic to wheat, some of these fragments can be recognized by the immune system and trigger their disease," she says.
In people with non-celiac gluten sensitivity, an effect on intestinal permeability has been evoked. "Since the submucosa is particularly innervated, this permeability can generate symptoms such as bloating or diarrhea," says Professor Bruno Bonaz, a gastroenterologist. However, without knowing why, this does not concern everyone. "One of the avenues explored is the interindividual difference in the perception of sensations: the interception or awareness of the internal state of one's body," continues Professor Bonaz. It can be assumed that the nerve signals sent by the intestinal sphere to the brain can be amplified in some. These could often be people who are stressed, anxious, or depressed.
In the absence of characteristic markers as in celiac disease or wheat allergy, only the exclusion of gluten can determine whether digestive difficulties are related to its ingestion. And again: not for sure.
Does it reduce inflammatory bowel disease?
No, with the exception of celiac disease. "It is only in celiac patients that the ingestion of gluten causes an inflammatory reaction, easily detectable by blood markers," recalls Professor Cellier. This damages the intestinal wall and destroys its villi: this is what requires the total eviction of foods that contain it. »
When it comes to other inflammatory bowel diseases or irritable bowel syndrome, gluten is not involved and does not aggravate inflammation. "On the other hand, we can think that his eviction makes it possible to alleviate the symptoms, insofar as he is poorly digested by some," says Bruno Bonaz. The American Rheumatology Society recommends adopting a gluten-free diet during flare-ups. Thus, people suffering from inflammatory digestive diseases report feeling better gluten-free.
Are joint or rheumatic disorders improved?
Yes, in some. Again, no cause-and-effect link, no scientific evidence, but testimonies. "It is assumed that gluten could increase the inflammatory state in these patients by increasing intestinal permeability," suggests Bruno Bonaz. But without proof. »
Does it have an impact on diabetes?
Not at all, or indirectly. "It is only in celiac disease that we observe a link between gluten and type 1 diabetes," recalls Christophe Cellier. In both cases, autoimmune diseases. As for the effect that a gluten-free diet can have on type 2 diabetes, it depends mainly on the food hygiene adopted. "If it is a question of replacing wheat and its derivatives; industrial products such as bread, pizzas, biscuits... Gluten-free, the effect is rather harmful because these products are often enriched with sugar and fats and the flours used have a high glycemic index," notes Cédric Ménard, dietician. "If, on the contrary, removing gluten means eating healthier by reducing the share of industrial products and increasing the share of fresh, naturally gluten-free products such as fruits and vegetables, meats, fish... the impact on health parameters can be positive," adds Dr. Nadine Cerf-Bensussan.
Does it help to slim down?
Sometimes. It all depends, again, on what the gluten-free diet is made of. If by eliminating foods that contain it, one reduces one's consumption of industrial products, this can lead to a decrease in energy intake. "If, on the other hand, we do not change the way we eat and we simply swap gluten products for gluten-free products, the effect could on the contrary be negative," suggests Nadine Cerf-Bensussan. "Gluten does not make you fat or lose weight," says Christophe Cellier.
Are we more fit, less tired?
Maybe. But this effect is then indirect. "We are leaning towards a placebo effect," says Professor Cellier. When you change your diet, when you are convinced that you are doing yourself good, it can generate a certain dynamism. In addition, the easier the digestion, the lighter and fitter you feel. What about athletes who claim to see their results increase tenfold with a gluten-free diet? "A study has been conducted in the United States on this subject among cyclists, notes the gastroenterologist. The latter was blindly subjected to diets with and without gluten. Conclusion: there is no difference in performance. »
Professor Bonaz's opinion is less clear-cut: "It is possible that by modifying the permeability of the intestinal wall, gluten manages to cross the intestinal barrier and is found in circulation in the blood. This could act at the level of the cerebral barrier (blood-brain) or at the level of the vagus nerve and thus generate fatigue, headaches ... But these are just assumptions. »
Are allergies reduced?
No. With the exception of wheat allergy and celiac disease in which the ingestion of gluten leads to an inadequate reaction of the body's immune defenses, gluten does not generate allergic reactions. "Here again, the improvement described by some may be indirect," says Professor Bonaz. When you digest better, you are less stressed, which can reduce allergic reactions. The relationship between the brain and the digestive tract should not be dismissed. »
Does the gluten-free diet positively impact mood and cognitive abilities?
Apparently, in some. Several hypotheses are put forward: the placebo effect, the relationship between the intestines and the brain, the composition of the microbiota. "A growing body of evidence shows that it can influence behaviour and sensitivity to stress," says Nadine Cerf-Bensussan. The consumption of gluten could perhaps modulate the composition of the intestinal flora. Nevertheless, nothing is demonstrated. »
What conclusions?
There is a sensitivity to non-celiac gluten that manifests itself in digestive and extra-digestive symptoms that arise after ingesting it, and disappear when it is ousted. But "there is no objective criterion to establish a diagnosis," recalls Professor Cellier.
Unlike celiac disease and wheat allergy, this sensitivity does not have a serious character. "Excluding gluten improves the discomfort felt, but it is possible for these people to consume it without consequences for their health," notes Bruno Bonaz.
While there is currently no scientific explanation, several hypotheses have been put forward, such as the links between the brain and the intestines or the microbiota. The problem may not be limited to gluten. "Some specialists speak more of a sensitivity to wheat," notes Bruno Bonaz. It is, in fact, important to take into account the other components of the offending foods in the symptoms felt (FODMAPs). »
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