Infant Egg Allergy Unaffected by Mom’s Early Postnatal Diet

Infants were no less likely to develop egg allergy if their mother ate eggs in the days after delivery as a means of low-dose oral immunotherapy via breast milk, a randomized clinical trial showed.

At 12 months of age, egg allergy rates were similar for children whose mother consumed eggs in the 5 days after giving birth as for those whose mother eliminated eggs during that early neonatal period (9.3% vs 7.6%, risk ratio [RR] 1.22, 95% CI 0.62-2.40), Mitsuyoshi Urashima, MD, MPH, PhD, of Jikei University School of Medicine in Tokyo, and colleagues reported in JAMA Network Open.

The same was true for sensitization to egg white (RR 1.13 at age 4 months, 95% CI 0.81-1.56, and RR 1.07 at 12 months, 95% CI 91-1.26), which was common in both groups at 12 months of age: 62.8% with early maternal consumption and 58.7% with early maternal elimination.

“The prevalence of food allergy is increasing, estimated at approximately 10% in children,” the researchers wrote. “Notably, the hen’s egg is one of the most common causative foods for food allergies and anaphylaxis. Thus, preventing egg allergy [EA] is important for children.”

“Generally, egg proteins secreted into breast milk as a result of the maternal egg intake are minuscule,” they added. “Therefore, we hypothesized that administering eggs via breastfeeding during the early neonatal period (0-5 days) prevents EA, acting like spontaneous low-dose oral immunotherapy. To examine this hypothesis, this multicenter [randomized clinical trial] was conducted to assess whether maternal egg consumption or elimination by mothers in the first 5 days after delivery prevents infants’ EA.”

Researchers conducted the trial at 10 medical facilities in Japan from Dec. 18, 2017 to May 31, 2021. Mothers in the early egg consumption group consumed one cooked egg per day in addition to their normal breakfast from days 0 to 5 following birth, while the other group received a hospital diet that eliminated eggs during the same time period. The trial randomized 380 infants and their mothers, with 183 completing the 12-month follow-up.

Adherence to the egg-consumption randomization, breast milk consumption, and infants’ diet after the randomized period during follow-up were similar between groups.

Egg allergy at 12 months of age was defined as a sensitization to egg white or ovomucoid — a protein found in egg whites — plus a positive test result in an oral food challenge or an episode of obvious immediate symptoms after egg ingestion.

Allergy prevention is an important area of study for pediatric food allergy, Vincent Tubiolo, MD, of the Allergy, Asthma, and Immunology Care Center of Santa Barbara, California, told MedPage Today in an email. Most studies have suggested that timing, and probably dosage as well, make a difference. “In the case of egg, the degree of heating is also relevant,” Tubiolo added. “For example, if egg proteins are extensively heated (baked for 30 minutes in a cupcake), they are often less allergenic than a boiled egg.”

“As the authors mention, 3-6 months of age appears to be an optimum time to introduce eggs in most predisposed children, but can be too late for others,” Tubiolo added. “Studies related to in utero avoidance measures of food allergens have had conflicting and somewhat confusing results. Variables including the allergic status of the parents affected those studies. Finding another ‘sweet spot’ between birth and 3 months could help limit egg allergy in some of the children who do not benefit from waiting until age 3-6 months.”

“A message for clinicians is that we should continue to observe our own ‘real world’ patients for clues on the role maternal and infant diets play in preventing food allergy,” Tubiolo added.

Randomization to early egg exposure did make a difference in egg white proteins detected in mothers’ breast milk on days 3 to 4 following birth. Milk contained ovalbumin and ovomucoid five-fold more often in the egg-consuming group than in the elimination group.

Peak levels of those egg white proteins in breast milk at 3 and 6 hours after egg consumption were significantly higher in the egg-consumption group as well. The difference disappeared after the intervention, with no significant difference at 1 month of age between the groups.

Among other findings, researchers reported that eczema, milk, and wheat allergies at 1 and 4 months of age did not differ significantly between randomized groups, nor did sensitization to milk and wheat.

Food protein-induced enterocolitis syndrome due to eggs was observed in one infant in each group.

Researchers reported no adverse events in either group during the intervention period of 0 to 5 days following birth.

Limitations of the study included the lower overall prevalence of egg allergy (8.4%) than the initially expected 15%, researchers noted. Egg allergy was also diagnosed using an open oral food challenge rather than double-blind food challenges.