Wheat allergy is responsible for an number of different types of adverse reactions involving the skin, the gastrointestinal tract and the respiratory system, with IgE mediated reactions occurring more commonly in childhood than in adulthood. Children who are sensitised to wheat via the gastrointestinal tract tend to loose this sensitivity as they get older. It would however appear that wheat sensitivity is more pronounced in older children, suggesting teens also affected by wheat allergy.
It is important to clarify what type of reaction is responsible for symptoms in wheat allergy, whether cell-mediated, IgE, or non-immune mechanisms causing the adverse reaction. Coeliac disease is an example of a cell-mediated gastrointestinal reaction. The proteins most commonly associated with IgE reactions are gliadin and glutenin, with omega-5 gliadin being the most common allergen in young children, causing immediate IgE reactions. Levels of this particular allergen may be higher in those with more severe symptoms including anaphylaxis. Wheat is also reported to be a factor with many people with irritable bowel syndrome, although the mechanism is unclear.
There is relatively little information about the prevalence of wheat allergy, due mainly to the large discrepancy between reported allergy to wheat and actual allergy, as confirmed by a double-blind-controlled-food-challenge (DBCFC). Skin Prick Testing and specific wheat IgE blood tests are poorly predictive of allergy, with less than a 50% positive predictive value, however omega-5 gliadin specific IgE blood testing may be a more useful indicator to determine wheat allergy in young children. Dietary and clinical history is an important part of making a diagnosis of wheat allergy, although this can be made more difficult due to the large number of foods that wheat is found in. There is high cross-reactivity with grass pollen, and this should ideally be excluded before wheat allergy can more accurately be confirmed.
Avoiding wheat in the diet can put children at risk of deficiencies of energy, B vitamins, calcium and iron, and so specialist advice on wheat avoidance is necessary. Substitutes for wheat include corn, rice and potato, with many specialist foods being available in supermarkets. Gluten free foods are often not a suitable alternative for wheat allergy, as they often contains wheat starch, although many supermarkets stock a good range of special food products. Wheat is required to be highlighted on food labels and declared as ingredients in restaurants.