Dietary Restriction Status for Hen’s Egg, Cow’s Milk, and Wheat in Relation to Plasma Amino Acid Profiles, Growth, and Insulin-like Growth Factor I in Children with Food Allergy

Background/Objectives: Food avoidance may compromise nutrient intake and growth in children with food allergy; however, its association with plasma amino acid profiles remains poorly understood. We aimed to examine dietary restriction status for hen’s egg, cow’s milk, and wheat in relation to plasma amino acids, growth, and insulin-like growth factor I. Methods: This single-center cross-sectional study included 80 children aged < 10 years. Dietary restriction status, defined based on the amount of each food medically permitted for routine daily consumption, was dichotomized as complete avoidance/minimal intake or partial/unrestricted intake. Plasma amino acids were available for 79 participants. Multivariable models included all three foods, with Benjamini–Hochberg correction. Results: No broad reduction in plasma amino acid concentrations was evident across dietary restriction categories, although several food-specific associations were observed. Less restrictive cow’s milk status was nominally associated with higher height standard deviation score (SDS) and lower aspartic acid concentration. Less restrictive wheat status was associated with lower weight SDS after multiple-testing correction (q = 0.046), although the complete avoidance/minimal intake group comprised only three participants. Among children with a cow’s milk allergy, threonine concentration was 34.2% lower in the partial/unrestricted group than in the complete avoidance/minimal intake group (q = 0.002). The minimum essential amino acid z-score was inversely associated with weight SDS and body mass index SDS (q = 0.023 for both). No association with the overall 20-amino-acid profile remained significant after multiple-testing correction. Conclusions: Dietary restriction status was not accompanied by a broad or uniform reduction in circulating amino acids. Instead, the observed pattern suggested selective rather than generalized differences, warranting confirmation in longitudinal studies with quantitative dietary assessments.