When the famous tennis player Novak Djoković announced that he was adopting a gluten- and lactose-free diet, few people were surprised. In fact, gluten-free food is currently all the rage. Economic experts predict that worldwide sales of gluten-free products will reach 3 billion euros by the year 2020.
Gluten is mainly associated with wheat, but this protein is also a component of other cereals such as rye, oats and barley. It is not toxic, but it can trigger various disorders in some people. It is important to distinguish between three different conditions: gluten allergy, gluten intolerance (coeliac disease) and non-coeliac gluten sensitivity.
Gluten allergy is rare. It is an abnormal reaction of the immune system, which considers gluten a foreign body, triggering a defence mechanism, either immediately or within a matter of hours after eating it. The body generally reacts with itching and swelling of the mouth, and sometimes by digestive, skin or breathing problems. Gluten intolerance, also called coeliac disease, is more insidious. In this case, the body is unable to digest gluten, and the disease causes symptoms such as digestive problems, as well as concentration difficulties and fatigue. While gluten allergy is triggered by the ingestion of a tiny quantity of gluten, with coeliac disease the symptoms are proportional to the amount of gluten absorbed – the higher the quantity eaten, the more intense the symptoms. Gluten allergy and coeliac disease are both the result of genetic predispositions and are easily diagnosed by specialists. In both cases, adopting a gluten-free diet is the only way to avoid the symptoms. However, unlike with gluten allergy or gluten intolerance, non-coeliac sensitivity to gluten, which more and more people claim to suffer from, is difficult to diagnose because, with this condition, the body does not make antibodies to attack the gluten. Gluten sensitivity is often linked with stomach ache but, for the moment, it is a nonspecific condition with no real scientific explanation. Patients often self-identify as having the condition, by associating their symptoms with those of gluten intolerance: diarrhoea or constipation, bloating, exhaustion, painful joints, headaches and skin rashes. The only way to relieve these problems seems to be to reduce the consumption of foodstuffs containing gluten. However, gluten may not be directly responsible for these symptoms. In fact, studies have shown that they could be caused by FODMAPs, an acronym derived from five types of sugars present in the dietary fibres of certain plants (Fermentable, Oligo-, Di-, Mono-saccharides And Polyols). FODMAPs are found naturally in foodstuffs that contain gluten. A diet that is low in FODMAPs could thus explain an alleviation of the symptoms, without gluten being responsible.
The true extent of gluten sensitivity is therefore still unclear. In the meantime, health experts point out that it is important to consult a doctor before starting a gluten-free diet as, when gluten is cut out altogether, a gluten-intolerant person would no longer produce antibodies and this would impede a reliable diagnosis of the disease. Moreover, a gluten-free diet is not without risk. Premenopausal or menopausal women who stop eating lactose and gluten are particularly vulnerable. They are at risk of developing deficiency diseases, notably osteoporosis, if they do not take steps to compensate for the lack of calcium. In general, the risk of deficiencies is high, as foodstuffs that do not contain gluten, such as rice or corn, are low in fibre, folic acid, zinc and vitamins. A gluten-free diet is also dangerous for children whose state of health does not require a specific diet. They are particularly at risk of lacking in B vitamins, important for the nervous system to function, and trace elements, necessary for growth.