The influence of diet on health has been recognized for centuries. If the ingestion of food results in adverse reactions, this may be the result of hypersensitivity to an antigen or hapten present in the food, or due to a failure of absorption as a result of the deficiency of brush border enzymes such as lactase, or nonspecific release of histamine from mast cells without involvement of reaginic antibodies. Among the sensitizing substances present in diet may be mentioned various proteins, drugs (e.G. penicillin, salicylates), dyes and preservatives (e.g. tartazine, benzoates).