Baby Formula in First 3 Days of Life May Increase Peanut Allergy Risk

A new study suggests that baby formula feeding in the first 3 days of a newborn’s life may be a risk factor for peanut or multiple food allergies.1

“This early [formula] supplementation was associated with a five-fold increase in the risk of developing peanut allergy, which can be life-threatening and long-lasting,” wrote study investigator Maheshwar Bhasin, PhD candidate, from the Larsson-Rosenquist Foundation Centre for Immunology and Breastfeeding at the University of Western Australia, and colleagues.1 “Early supplementation was also associated with an 11-fold increase in the risk of developing more than one food allergy by 12–18 months.”

Many infants receive baby formula exclusively or as a supplement to breastmilk. In 2018, the CDC reported that 54% of infants received formula, with 19% of breastmilk-fed infants receiving supplement formula within 2 days of life.2

Early formula feeding the first 3 days of life has been shown to have drawbacks, increasing the risk of cow’s milk allergy and reducing colostrum intake, which is rich in bioactive compounds critical for immune and gut health. During the first 3 days of a newborn’s life, new mothers produce colostrum—their breastmilk—in small amounts (~30 mL per 24 hours).

Colostrum contains growth factors, vitamins (vitamin A and carotenoids), anti-inflammatory molecules (TGF-beta), and microbiota-shaping molecules (Human Milk Oligosaccharides, IgA, and lactoferrin). These nutrients are 5 – 10 times greater in colostrum than in mature milk and are either low or absent in formula milk.

Investigators conducted a study to assess whether partial colostrum feeding—using baby formula—increases the risk of food allergy beyond cow’s milk. Leveraging participants from the Australian ORIGINs cohort, the study included 666 mother-infant pairs, categorized as either exclusive colostrum-fed (only breastmilk) or partial colostrum-fed (formula plus breastmilk) within the first 3 days. Clinicians diagnosed IgE-mediated food allergy at 12 to 18 months using skin prick tests and mothers’ reports of immediate reactions to allergens.

In the sample, 46% infants were partially colostrum-fed; most of these infants received formula within the first 24 hours of their life (median 21.8 hours), and 5.7% received formula as their first feed. About half of the partial colostrum-fed infants (47%) received formula for medical indications, including hypoglycaemia (45%), jaundice (24%), and weight loss (21%).

Compared to infants fully fed breastmilk, infants who were partially colostrum-fed had an increased risk of peanut allergy (adjusted odds ratio [aOR], 4.47; 95% confidence interval [CI], 1.04 to 19.12) and multiple food allergies (aOR, 11.44; 95% CI, 1.48 to 88.55).

Partial colostrum-fed infants introduced to peanuts at 7 months or later faced a greater risk of developing peanut allergy. Breastmilk-fed infants maintained a low peanut allergy risk despite the timing of their peanut introduction.

Investigators also explored the effect of reduced colostrum intake from formula feeding, assessing the association between the number of colostrum feeds and allergic outcomes. They found that no peanut allergy cases occurred in infants receiving ≥ 9 colostrum feeds per day within their first 72 hours, regardless of the infant also receiving formula.

“Our findings open new avenues for food allergy prevention and have implications for both medically and non-medically indicated formula supplementation,” investigators wrote. “To address non-medically indicated supplementation, efforts should prioritize the promotion of exclusive colostrum feeding…This includes ensuring all healthcare professionals involved in postnatal care receive evidence-based breastfeeding education, and providing parents with consistent, accurate information on the benefits of colostrum feeding and the potential risks associated with formula feeding. For medically indicated supplementation, our findings suggest that increasing colostrum intake alongside formula supplementation and/or emphasizing the importance of earlier allergen introduction may help to reduce food allergy development.”

References

1. Bhasin M, Cooper M, Macchiaverni P, et al. Colostrum as a Protective Factor Against Peanut Allergy: Evidence From a Birth Cohort. Allergy. Published online September 18, 2025. doi:10.1111/all.70043

2. Williams E, Artiga S. Key Characteristics of Infants and Implications of the Recent Formula Shortage | KFF. KFF. Published June 9, 2022. Accessed October 10, 2025. https://www.kff.org/medicaid/key-characteristics-of-infants-and-implications-of-the-recent-formula-shortage/