[Food allergies are often an unrecognized cause of clinical complaints].

While 6% of children under three years of age suffer from a food allergy, the figure for adults varies between 1.5 and 3%. Leading allergens in foodstuffs are glycoproteins having a molecular weight of between 10,000 and 60,000. The symptoms of an immediate type nutrient allergy mediated by IgE usually manifest within a matter of a few minutes to two hours after ingestion of the offending nutrient and take the form, for example, of tingling and itching, tissue swelling in the mouth, hoarseness, asthma, gastrointestinal complaints or acute urticaria; in severe cases anaphylactic shock may even occur. In contrast, no IgE antibodies are to be found in nutrient-induced enterocolitis, which is associated with diarrhea and vomiting occurring after a delay of one to six hours. Differential diagnostic considerations must include intolerance for certain foodstuffs, such as lactose intolerance, or pseudoallergic reactions.