Pitfalls in double-blind, placebo-controlled oral food challenges

Although controlled oral food challenges are considered to be the gold-standard in the diagnosis of food related symptoms, especially if performed in a double-blind, placebo-controlled food challenges (DBPCFC) manner, there are still many unanswered questions and newer aspects, which may explain some pitfalls encountered during oral food challenges. For stopping an oral food challenge and declaring a challenge as positive or negative, symptoms should be objective and/or repetitive. The time interval between administering the food and observing the clinical reaction is an ambivalent factor. Possible reasons for false negative assessments include inadvertent drug use during oral challenges, and the fact that a short-term specific oral tolerance induction (SOTI) may be induced as increasing amounts of the offended food are administered during a titrated oral food challenge. Possible reasons for false positive assessments are the difficulty to maintain an appropriate strict diet throughout the oral challenge procedure, and that the elimination diet implemented before the oral food challenge in children with atopic eczema and suspected food related symptoms may itself be responsible for immediate type clinical symptoms, which had not been reported by the parents before. Finally augmentation factors are among the most plausible explanations for the inadequate reproducibility of an oral food challenge. Although a 100% standardization of the challenge procedure does not seem realistic, efforts should be made to improve the methodology used so far. On the contrary, the possible relation of DBPCFC and SOTI may offer potential advantages for future therapeutic approaches of food allergy.