Aim: This study evaluates the sociodemographic, clinical, and anthropometric data of infants diagnosed with Food Protein-Induced Allergic Proctocolitis (FPIAP), categorized as exclusively breastfeeding or formula feeding at the onset of symptoms. This division allows us to compare the effects of different feeding on the development of FPIAP.

Methods: This retrospective, observational, single-center study included infants ≤36 months diagnosed with FPIAP. Exclusion criteria were chronic morbidities to ensure a focused study population. Data was collected using the Food Allergy Standard Protocol, meticulously coded, and stored in a secure database.

Results: Two hundred one were identified with FPIAP, breastfeeding (25%), and cow's milk formula (75%). The age at the onset of symptoms, at the first visit, and the diagnosis delay were lower for breastfeeding. for the first symptom, there was a higher proportion of breastfeeding in <180 days. Conversely, there was a higher proportion of cow's milk formula for children over 180 days. For Age at first visit, there was a higher proportion of breastfeeding in those <180 days and a higher proportion of cow's milk formula in those >180 days. Blood-streaked stools were present in 72% (breastfeeding) and 81% (cow's milk formula).

Conclusions: The findings of this study have implications for clinical practice. FPIAP, with its monotonous clinical presentation and lack of laboratory validity for diagnosis, should be considered in the differential diagnosis of hematochezia. The similarity of FPIAP presentation to studies in industrialized/Westernized countries is notable. However, the lower prevalence of FPIAP with breastfeeding suggests the need for a prospective study analyzing perinatal and environmental variables, which could provide valuable insights for future research.

Food allergy, Proctocolitis, Exclusively breastfeeding, Formula feeding, Infant, Children, Hematochezia, Blood stools