Factors affecting the development of food allergy.

Food allergy is an important health issue. The estimated prevalence among adults in Western Europe is thought to be between 1 and 2%, with the frequency in infants being greater (approximately 5%). Most confirmed food allergies are associated with a relatively limited range of produce, including cow's milk, eggs, tree nuts, peanuts, wheat, fish and shellfish, although the prevalence of allergy to individual foods is known to vary geographically, due largely to differences in dietary practices. Although formal evidence is lacking, it is assumed that (in line with other forms of atopic disease) the incidence of food allergy is increasing. There is no doubt that genetic predisposition is an important determinant. However, acquisition of sensitisation to food proteins and subsequent allergic disease is known to be influenced by a variety of environmental factors and the timing, duration and extent of exposure. Moreover, the nature of the allergen itself may have an important impact on the severity and persistence of clinical disease. The purpose here is to discuss the relevance of some of these variables in the context of immunoglobulin E antibody-mediated allergic responses.