Growth Outcomes and Dietary Strategies in Non-IgE-Mediated Food Allergies

Background/Objective: Non-IgE-mediated food allergies (non-IgE-FAs) are increasingly recognized in infancy as causes of delayed gastrointestinal symptoms, nutritional compromise, and impaired growth. This retrospective study aimed to evaluate longitudinal growth outcomes in children with non-IgE-FAs managed with different dietary interventions and to explore phenotype-specific differences and clinical correlations. Methods: Children diagnosed with non-IgE-FAs at the Pediatric Clinic Unit of Salesi Hospital (Ancona, Italy) between July 2022 and June 2025 were included. Anthropometric, clinical, and laboratory data were collected at baseline (T0) and follow-up visits at 6, 12, and 18 months. Weight-, length-, and BMI-for-age z-scores were calculated using Growth Calculator 4.0. Longitudinal growth trends were assessed through individual linear regression slopes, and dietary intervention effects were evaluated with ANOVA models. Results: Thirty-seven children were included (57% male), 95% of whom were diagnosed with CMA. Slope analyses demonstrated significant positive trends for BMI z-scores (median 0.340, IQR −0.171 to 1.130; p = 0.013). BMI slope differed according to phenotype when comparing children with FPE and those with FPIAP (mean slope = 0.068 ± 0.795 vs. 0.782 ± 0.873, respectively; p = 0.048). No significant differences in BMI improvement were observed between children on an elimination diet, breastfed children whose mothers followed an elimination diet, and those on a free diet. Conclusion: Dietary management in children with non-IgE-FAs was associated with improved growth trajectories, particularly in BMI-for-age z-scores. Children with FPE showed a less favorable BMI trajectory than those with FPIAP. Although the choice of dietary strategy did not significantly affect growth outcomes in this cohort, individualized nutritional assessment and judicious use of elimination diets remain essential. Larger prospective studies are needed to refine phenotype-specific nutritional strategies and optimize long-term outcomes.