[Food allergy: definition, diagnosis, epidemiology, clinical aspects].

Contrary to the lay and media perception, adverse reactions to foods (and food additives) occur less often than believed by the patients. The term food intolerance (FI) is widely misused as a cause of all sorts of symptoms and diseases. This diagnosis is often based on "alternative" techniques. Food allergy (FA) is the correct diagnosis if the symptoms resulting from the ingestion of a food (or an ingredient) are due to an immune mechanism. This diagnosis is seldom difficult in the case of a severe reaction immediately after ingestion of the food and when skin prick tests and/or IgE antibodies to the incriminated food are clearly positive. However, the best way to establish FA/FI is-apart from exclusion from the diet, which tends to have a marked placebo effect-the performance of proper double-blind, placebo-controlled food challenges (DBPCFC). Evidently, there are difficulties in conducting studies of this nature in a large population sample, and so far only three prevalence studies in Dutch and English adults have been based on DBPCFC. The reported prevalences of FA/FI (questionnaire answers) were 12% to 19%, whereas the confirmed prevalences varied from 0.8% to 2.4%. For additive intolerance the prevalence varied between 0.01 to 0.23%. The consequences of mistaken perception of FA/FI, which can have a major social impact in financial and health terms, require an information campaign for doctors, lay and media in connection with these problems.