Estimating prevalence of adverse reactions to foods: principles and constraints.

Future research in the area of adverse reactions to foods should use the basic principles of epidemiology to allow the prevalence of these adverse reactions to be established. The process of incorporating these principles into future research will aid in the identification of the etiology of adverse reactions through the clarification of definitions, refining of testing and assessment procedures for classifying reactions, and the identification of the populations who are indeed at risk for the numerous types of reactions that may occur. Although the evaluation of adverse reactions is a challenging problem, it is a problem that can be overcome.