The gluten-free diet is widely discussed by the public and promoted by the media and the food industry. It has become the most common diet in the United States, surpassing the fat-free and sugar-free diets. The indications for the diet are mainly celiac disease, wheat allergy, and non-celiac gluten sensitivity. The true pathogenesis of the latter is not yet known. Other indications for this diet are found in the medical literature and are used by the general public to treat a wide range of problems, from psychiatric disorders to athletic failure. We will review the arguments for or against a gluten-free diet in various situations.
Celiac disease is an autoimmune reaction in which gliadin, a peptide that breaks down gluten, causes an inflammatory reaction in the duodenal wall. This leads to digestive and extraintestinal manifestations. Rare but dangerous long-term complications include T-cell lymphoma-associated enteropathy, small intestinal adenocarcinoma, and other gastrointestinal neoplasms. The diagnosis of celiac disease is made by testing for IgA antibodies to antitransglutaminase or, in the case of IgA deficiency, IgG antibodies to antitransglutaminase and IgG antibodies to deaminogliadin peptide. The only currently recognized treatment is a strict gluten-free diet. Consultation at least once a year is necessary to assess compliance and monitor the development of any deficiencies or complications.
Wheat IgE allergy exists mainly in two forms: classic food allergy and exercise-induced anaphylaxis after consuming wheat (WDEIA). Classic food allergy manifests within minutes to hours after ingestion of wheat and includes skin, digestive, respiratory and cardiovascular reactions, up to and including anaphylactic shock. WDEIA manifests within hours after ingestion of wheat, and includes a wide range of symptoms, from urticaria to anaphylaxis. However, it occurs only in the presence of an additional factor, such as exercise, alcohol, or acetylsalicylic acid. The only treatment is elimination of wheat from the diet or removal of the additional factor in the case of WDEIA.
IgE-mediated allergies are diagnosed by skin testing, blood tests for specific IgE antibodies (beware of cross-reactions with other plants and foods) or even a supervised provocation test. There are other types of allergic reactions to wheat, such as eosinophilic esophagitis or eosinophilic gastroenteritis.
Non-celiac gluten sensitivity
It refers to patients with digestive and/or extraintestinal symptoms caused by gluten intake that disappear with a gluten-free diet and in whom celiac disease and wheat allergy have been ruled out. Various synonyms are used for this type of gluten allergy: non-celiac gluten intolerance, gluten hypersensitivity, wheat sensitivity.
Clinical picture of non-celiac gluten intolerance
Symptoms appear after consuming gluten at intervals of three days and disappear when a gluten-free diet is followed. Symptoms such as irritable bowel syndrome are worth mentioning in this context, as are a number of other common symptoms characteristic of this type of gluten intolerance.
The pathophysiology of non-celiac gluten intolerance is currently very poorly understood. Whereas the adaptive immune system is involved in celiac disease, the innate immune system appears to be involved in gluten intolerance. Indeed, several markers of innate and acquired immunity differ in quantity in both diseases. In addition, gluten is thought to cause gastrointestinal mucosal damage not mediated by the immune system in both celiac disease and gluten intolerance. Peptides, whether or not derived from gliadin, can cause direct damage to epithelial cells, particularly by inhibiting DNA and RNA synthesis, increasing oxidative stress and inducing apoptosis. These peptides are also thought to cause gastrointestinal motility disorders through increased release of acetylcholine from the myenteric plexus and direct stimulation of the enteric nervous system. However, there is a paucity of literature on this issue, and other mechanisms probably exist.
In order to diagnose gluten intolerance (food allergy IgG), we must first rule out celiac disease and wheat allergy type I (food allergy IgE).
For the detection of gluten intolerances and other food intolerances we offer you the possibility to have a blood test (test has 270 parameters) at our medical center.
Eliminating gluten from the diet (if intolerant) should result in a clear regression of intestinal and general symptoms.
A gluten-free diet is also recommended for a patient with celiac disease. However, dietary control may be necessary to avoid an increase in fat or sugar intake, which is often the result of excluding gluten from the diet, and to avoid vitamin, micronutrient, and mineral deficiencies.
Gluten-free diet and specific clinical situations
An analysis published in 2014 involving 2,239 women showed a significant association between infertility and undiagnosed celiac disease, suggesting that celiac disease is a risk factor. However, there is no evidence that in patients without celiac disease, a low-gluten diet can resolve infertility.
Fibromyalgia shares some symptoms with gluten intolerance. There is a study that describes a clinical improvement after excluding gluten from the diet for 16 months in twenty patients with fibromyalgia. However, no randomized controlled trial has shown a benefit of such a diet in this situation.
In rheumatoid arthritis, various diets are widely practiced by patients despite the lack of evidence. A randomized trial of patients with active rheumatoid arthritis who followed a gluten-free vegan diet showed clinical improvement in 40.5% of patients compared with 4% of patients who followed a normal balanced diet. However, to our knowledge, there are no studies including only the gluten-free diet.
Depression and anxiety may occur in untreated celiac disease. These disorders usually improve after starting treatment, but may sometimes persist and require special treatment. Some patients report that they feel better on a gluten-free diet, but that their digestive symptoms do not improve.
The diet has also been suggested for the treatment of autism, due to a theory suggesting that gluten and casein play a role in its pathogenesis. However, the Cochrane review concluded that the evidence for this is currently weak.
In addition, there is anecdotal clinical evidence that gluten reduction or withdrawal in children without celiac disease may improve sleep and mental concentration.
Many top athletes avoid gluten to improve their physical performance. In a study that analyzed the behavior of 910 non-celiac athletes, 41% reported following a gluten-free diet 50 to 100% of the time. These were mostly people involved in endurance sports. Among them were eighteen world and Olympic medalists! Most thought they would improve their performance (56.3%) and reduce gastrointestinal problems (61.1%). The main source of information was the Internet (28.7%), followed by coaches (26.2%) and other athletes (17.4%), well ahead of medical advice (0.5%). Although self-belief can improve an athlete’s performance (1 to 3% according to some authors) through a placebo effect, there is no evidence for this. Given the limitations of this diet and the potential drawbacks it can cause, further research is needed.