The role of the gastrointestinal tract in the development of respiratory hypersensitivities.

Adverse reactions to foods may sometimes cause symptoms from the respiratory tract, including bronchial obstruction and rhinitis. The true prevalence is not known. In adults, it has been estimated to be about 1% of asthmatic patients or less. This would correspond to a prevalence of about 2-4 in 10,000 of the general population. The prevalence in children is higher, as IgE mediated food allergy is more common in this age group than in adults. The most common foods causing immunologically mediated reactions include milk, egg, fish, crustaceans, nuts, wheat, soy, peanut, peas and other legumes. In addition certain food additives, e.g. sulphites, may rarely be incriminated in respiratory hypersensitivity via adverse reactions with unknown mechanisms. A double-blind placebo controlled food challenge (DBPCFC) is the only way to conclusively confirm a relationship between the ingestion of a certain food item and a reaction in the respiratory tract.