Dietary assessment in children adhering to a food allergen avoidance diet for allergy prevention

Objective: The purpose of this investigation was to verify if avoidance of allergenic foods in children adhering to a food allergen avoidance diet from birth was complete and feasible, and whether dietary assessment can be used as a tool in predicting the outcome of double-blind, placebo-controlled food challenges (DBPCFCs). Design: Children adhering to an allergen avoidance diet from birth underwent DBPCFCs. The investigator-dietician verified whether the elimination was complete, using food frequency questionnaires for common allergenic foods. Setting: University Medical Centre Groningen, the Netherlands. Subjects: Thiry-eight children aged 1-13 years, who were consecutively referred to the University Medical Centre Groningen for DBPCFC between January 2002 and February 2004. Results: Among the 38 children undergoing DBPCFCs, there were 15 challenges with egg, 15 with peanut, five with hazelnut and three with soy. Fifteen food challenges (39%) were positive. Small quantities of allergenic foods were inadvertently present in the diets of 13 patients (34%), were possibly present in the diets of 14 patients (37%) and could not be identified in the diets of 11 patients (29%). Seven patients (54%) who had inadvertently ingested small quantities of allergenic foods without sequelae had a positive DBPCFC. Conclusion: Dietary avoidance was incomplete and not feasible in most cases. Tolerance of small amounts of allergenic foods does not preclude positive challenge reactions. Dietary assessment does not seem a useful tool in predicting the outcome of DBPCFC in children adhering to an elimination diet.