The eventual development of egg allergy (EA) and sensitization to egg whites in infants is unaffected by maternal consumption of eggs during the early neonatal period, according to recent findings.¹

Egg proteins which have been secreted into breast milk due to maternal intake of eggs has been shown to be minuscule, so the investigators of this study hypothesized that administering eggs through breastfeeding in the early neonatal period prevents egg allergy could work as a kind of low-dose oral immunotherapy.²

The research was authored by Mitsuyoshi Urashima, MD, MPH, PhD, from the Division of Molecular Epidemiology at Jikei University School of Medicine in Japan.

“To examine this hypothesis, this multicenter RCT was conducted to assess whether maternal egg consumption (MEC) or elimination by mothers in the first 5 days after delivery prevents infants’ EA,” Urashima and colleagues wrote.

Background and Findings

The investigators conducted a single-blind randomized controlled trial (RCT) which took place in Japan at 10 facilities from December 18, 2017, to May 31, 2021. The research team’s study included neonates who had at least one parent with a medically diagnosed allergic disease, which was considered a high risk factor for developing food allergy.

The team’s specific exclusion criteria were applied, such as gestational age being below 37 weeks, birth weight being less than 2300 g, and neonates requiring admission to the newborn intensive care unit. Randomization was performed through the envelope method, and clinicians evaluating food allergies were blinded to the randomization results.

The investigators randomized mothers and their neonates in a 1:1 ratio to either the maternal egg consumption (MEC) arm or the maternal egg elimination (MEE) arm. In the MEC arm of the study, the investigators had the mothers consume one whole boiled egg per day between 0 and 5 days after delivery, while in the MEE group, eggs were eliminated from the mother's diet in the same period.

The normal hospital stay for postpartum in Japan is typically 5 days. Following discharge, no dietary restrictions were imposed on either study arm. By 1 month, both groups were given skin care and eczema treatment.

At the ages of 4 and 12 months, the team conducted blood assessments to evaluate egg sensitization, and an OFC was performed if certain criteria were met. Their OFC involved administering increasing doses of egg protein and then assessing the existence of objective or prolonged subjective symptoms.

The investigators’ primary study outcome at 12 months was egg allergy, determined by positive sensitization to egg allergens and confirmed through OFCs or immediate symptoms following egg ingestion. Secondary outcomes included measuring egg protein concentrations in breast milk, assessing food protein-induced enterocolitis syndrome (FPIES), evaluating sensitization to egg, milk, and wheat, and examining the existence of eczema.

Overall, out of the 380 newborns included in the study, 367 were followed up for 12 months. The investigators reported that on days 3 and 4 following delivery, the MEC arm had higher proportions of neonates with detection of ovalbumin and ovomucoid in breast milk compared to the MEE group (ovalbumin: 10.7% vs 2.0%; ovomucoid: 11.3% vs 2.0%). The risk ratios were 5.23 (95% CI, 1.56-17.56) for ovalbumin and 5.55 (95% CI, 1.66-18.55) for ovomucoid.

The research team noted that at the age of 12 months, they found were no significant differences between the MEC and MEE groups in terms of egg allergy prevalence (9.3% vs 7.6%; RR, 1.22; 95% CI, 0.62-2.40) or sensitization to egg white (62.8% vs 58.7%; RR, 1.07; 95% CI, 0.91-1.26). Additionally, no adverse effects were reported during the study.

“The proportion of neonates aged 3 to 4 days with OVA and OVM detected in their mothers’ breast milk was higher in the MEC group than in the MEE group,” they wrote. “However, EA at age 12 months was not significantly different between the MEC and MEE groups (9.3% vs 7.6%).”

References

1. ^{Nagakura K, Sato S, Shinahara W, et al. Effect of Maternal Egg Intake During the Early Neonatal Period and Risk of Infant Egg Allergy at 12 Months Among Breastfeeding Mothers: A Randomized Clinical Trial. JAMA Netw Open. 2023;6(7):e2322318. doi:10.1001/jamanetworkopen.2023.22318.}
2. ^{Metcalfe JR, Marsh JA, D’Vaz N, et al. Effects of maternal dietary egg intake during early lactation on human milk ovalbumin concentration: a randomized controlled trial. Clin Exp Allergy. 2016;46(12):1605-1613. doi:10.1111/ cea.12806.}