Abstract
BACKGROUND: Food allergy affects families' quality of life, can be lifelong and life-threatening, urging the identification of early modifiable risk factors. Formula feeding in the first days of life may increase the risk of cow's milk allergy, a risk often attributed to cow's milk allergens exposure. Early formula feeding also reduces the colostrum intake, the first 3 days' milk, which is rich in bioactive compounds critical for immune and gut health. This study investigates whether partial colostrum feeding increases the risk of food allergy beyond cow's milk. METHODS: Data from 666 mother-infant pairs in the Australian ORIGINS cohort categorised neonates as exclusive colostrum-fed (ECF, only breastmilk) or partial colostrum-fed (PCF, formula plus breastmilk) within the first 3 days. IgE-mediated food allergy (egg, peanut, cow's milk, cashew) at 12-18 months was determined by skin prick tests and maternal-reported immediate reactions to allergens. RESULTS: PCF prevalence was 46%. PCF infants showed an increased risk of peanut allergy [aOR (95% CI) 4.47 (1.04-19.12)] and multiple food allergies [aOR 11.44 (1.48-88.55)] compared to ECF infants. Risk was greater in PCF infants with later (> 7 M) peanut introduction [aOR 5.45 (1.18-25.11)], while ECF infants maintained a low risk regardless of timing. To disentangle the effect of reduced colostrum intake from formula feeding in PCF infants, we analysed the association between the number of colostrum feeds and allergic outcomes. No peanut allergy cases occurred in infants receiving nine or more colostrum feeds per day within their first 72 h, regardless of formula feeding. CONCLUSION: Partial colostrum feeding may be an overlooked risk factor for peanut and multiple food allergies. With over a third of neonates globally partially colostrum-fed, findings highlight the importance of promoting colostrum feeding and exploring colostrum-based therapies for high-risk infants.