Wheat allergy

Wheat allergy is an immunoglobulin E (IgE)-mediated or cell-mediated hypersensitivity to wheat proteins, including albumins, globulins, gliadins, and glutenins. The classic food allergy is IgE-mediated and typically occurs within minutes to two hours after ingestion, causing urticaria, angioedema, vomiting, or anaphylaxis. A delayed form, wheat-dependent exercise-induced anaphylaxis (WDEIA), is triggered by exercise or alcohol consumption shortly after eating wheat, often mediated by omega-5 gliadin-specific IgE. Another type, baker's asthma, is an occupational respiratory allergy caused by inhaling wheat flour, leading to rhinitis and asthma in bakery workers. These distinct mechanisms require different diagnostic and management approaches.

Diagnosis begins with a detailed history and physical examination, followed by skin prick tests and serum-specific IgE assays. For ambiguous cases, an oral food challenge under medical supervision is the gold standard. Once diagnosed, strict avoidance of wheat is the primary management, requiring careful reading of food labels and awareness of hidden sources such as soy sauce, modified food starch, and some processed meats. Antihistamines and epinephrine auto-injectors are used to manage acute reactions. For WDEIA, patients are advised to avoid exercise for several hours after wheat ingestion. Immunotherapy, including oral and sublingual routes, is under investigation but not yet standard practice.

Wheat allergy affects approximately 0.1–0.5% of children worldwide, with prevalence varying by region and diagnostic criteria. It is the third most common food allergy in children after milk and egg. Many children outgrow wheat allergy by age 12, with resolution rates reported as high as 65% in some cohorts. However, WDEIA and baker's asthma tend to persist into adulthood. The condition is more common in individuals with other atopic conditions, such as asthma, eczema, or allergic rhinitis. Genetic factors and environmental exposures, including the timing of wheat introduction in infancy, may influence risk, though research is ongoing.

Wheat allergy is often confused with celiac disease, but they are distinct: celiac disease is an autoimmune reaction to gluten, while wheat allergy is an immune response to various wheat proteins. A lesser-known variant is food protein-induced enterocolitis syndrome (FPIES) to wheat, a non-IgE-mediated reaction causing severe vomiting and diarrhea in infants. Another rare form is contact urticaria from wheat in cosmetics or playdough. Baker's asthma is one of the most common occupational lung diseases in Europe, yet it is underrecognized. Additionally, some individuals with wheat allergy can tolerate wheat that has been extensively hydrolyzed, such as in certain fermented products, but this is not universally safe and requires medical guidance.

IgE

Immunoglobulin E, an antibody involved in allergic reactions.

Anaphylaxis

A severe, potentially life-threatening allergic reaction.

WDEIA

Wheat-dependent exercise-induced anaphylaxis, a reaction triggered by exercise after wheat ingestion.

Baker's asthma

Occupational asthma caused by inhaling wheat flour.

FPIES

Food protein-induced enterocolitis syndrome, a non-IgE-mediated gastrointestinal allergy.