Prevalence of food allergy in asthma

Methodological problems limit the evaluation of the prevalence of food allergy in asthma. Methods commonly used in epidemiologic studies of allergic diseases (e. g. skin tests and eventually serum-specific IgE) are not reliable. Only double-blind food challenges combined with skin tests or specific IgE can screen asthmatics allergic to foods, but this method cannot be used in epidcmiologic studies. Thus, either epidemiologic studies are performed in a random population with inappropriate methods, or they are performed in selected populations with appropriate techniques. The prevalence of asthma due to food allergy is small, what ever patient group is considered, except in infants. In childhood asthma it may be considered that 4–7% of asthmatics have food-induced symptoms, but in adults it is under 2%.