Food protein-induced allergic proctocolitis: an early step on the atopic march

Food protein-induced allergic proctocolitis (FPIAP) has traditionally been considered a benign, non-immunoglobulin E (IgE)-mediated condition of infancy without long-term consequences. This review examines evidence challenging this framework and discusses FPIAP as an early manifestation of atopic susceptibility within the broader atopic march. We also review diagnostic limitations and the potential consequences of prolonged dietary elimination.

Epidemiologic data demonstrate significant independent associations between FPIAP and IgE-mediated food allergy, asthma, as well as other non-IgE-mediated conditions such as eosinophilic esophagitis (EoE) and food protein-induced enterocolitis syndrome (FPIES). These findings suggest overlap between IgE- and non-IgE-mediated allergic diseases, potentially reflecting shared immunologic pathways. A lack of standardized diagnostic criteria leads to the overdiagnosis of FPIAP contributing to unnecessary dietary restriction. Evidence further suggests that this overrestriction likely leads to the delay of introduction of allergens, potentially increasing risk for IgE-mediated food allergy in this population.

FPIAP may represent an early marker of atopic predisposition rather than an isolated gastrointestinal disorder. Recognizing its potential role within the atopic march has important implications for diagnosis, dietary management, and timing of allergen introduction. Improved diagnostic precision, earlier reintroduction of offending allergen, and timely introduction of other food allergens may reduce unnecessary restriction and mitigate downstream atopic risk.