Rational Use of Elimination Diets in Infants and Toddlers: Navigating the Overlap Between Disorders of Gut–Brain Interaction (DGBI) and Food Allergy—A Narrative Review

Disorders of gut–brain interaction (DGBI) are the most common cause of gastrointestinal symptoms in infants and toddlers. The overall prevalence in the pediatric population aged 0–48 months is approximately one in four children. DGBI symptoms such as excessive crying, regurgitation, constipation or altered bowel movements can often mimic or overlap with food allergy (FA) manifestations, especially non-IgE-mediated allergy, thus posing a diagnostic and therapeutic challenge. As a consequence, prolonged empiric elimination diets are often initiated in DGBI management despite limited evidence-based data. Although temporary clinical improvement may be observed and suggestive of FA, failure to perform allergen reintroduction can lead to unnecessary elimination, serious nutritional deficiencies, compromised development of oral skills, neophobia and reduced quality of life for both the child and its caregivers. It can also increase healthcare costs. The aim of this narrative review is to identify current evidence supporting the use of elimination diets in the most common DGBI in infants and toddlers, which include infantile colic, regurgitation, dyschezia and functional constipation, as well as functional diarrhea. We also emphasize distinguishing physiological and functional symptoms from allergy symptoms, as well as identifying clinical situations where both conditions can co-exist, thus justifying diagnostic elimination diets. Finally, we highlight both the benefits and potential harms of dietary restrictions in order to support an accurate diagnostic approach and optimize nutritional management.