Baked eggs in infancy may lower lifelong egg allergy risk

Feeding babies baked eggs early could prevent egg allergies—new research reveals how timing and exposure shape immune tolerance!

Study: Tolerance to cooked egg in infants with risk factors for egg allergy after early introduction of baked egg. Image Credit: Dragana Gordic / Shutterstock

A recent study finds that egg allergies in children can be prevented by introducing baked eggs to their diet at an early age and maintaining the diet for at least six months. The study findings are published in the journal Allergologia et Immunopathologia.

Background

Food allergies, including egg allergy, cow milk allergy (CMA), and atopic dermatitis (AD), are the most common allergies among children and adolescents. Up to 70% of infants with CMA or AD in the study were sensitized to eggs (detected via IgE testing), though only 36% of these reacted to baked eggs in controlled challenges. Lack of exposure to food allergens at an early age can increase the risk of developing food allergies in children.

The gold-standard methods for diagnosing food allergies are the skin prick test (SPT), specific immunoglobulin E (IgE), basophil activation test (BAT), and oral food challenge (OFC). Notably, the study identified egg white IgE levels <0.63 kU/L as a safe cutoff for baked egg tolerance, suggesting that infants below this threshold may be able to consume baked eggs safely. Several treatment strategies are available for food allergies, including avoidance of allergic foods, oral immunotherapy, and treatment with biologics.

Among various food allergies, egg allergy has a good prognosis in most cases. However, up to 20% of cases of childhood egg allergy can continue into adulthood.

Although mostly treatable, some food allergies can be life-threatening due to the development of severe immune reactions. Tolerance to food allergens seems to be driven by regular exposure to the allergens during the early stage of immunologic development. In this context, existing evidence suggests that the most suitable timeframe for allergen exposure is between four and six months of age.

In the current randomized controlled clinical trial, researchers in Spain explored whether introducing baked eggs into the diet of infants aged four to six months and continuing the diet for the next six months can effectively prevent the risk of egg allergy.

Study Design

A total of 27 infants (74% male) below six months of age who had CMA, AD, or both were enrolled for the trial. None of them had prior exposure to eggs.

All infants were provided with baked eggs and tested for their tolerance before the beginning of the trial. Infants who had no tolerance for baked eggs were advised to follow a diet without eggs and were categorized as “group A.” Similarly, infants who tolerated baked eggs were categorized as “group B.”

Group B infants were randomly assigned into two subgroups. One group consumed baked eggs daily for the next six months, and the other group avoided them during the same time period.

At the completion of six months, all infants underwent an oral food challenge test using hard-boiled eggs.

Trial Findings

The trial findings revealed that all infants who consumed baked eggs daily for six months tolerated hard-boiled eggs at that time, whereas only 47% of infants who consumed an egg-free diet tolerated hard-boiled eggs at the same time point (p = 0.012).

No significant differences in baked egg tolerance were observed between infants with CMA, AD, or both.

Infants with no tolerance to baked eggs at baseline exhibited significantly higher levels of specific IgE antibodies to egg white, egg yolk, and ovalbumin compared to those who tolerated baked eggs. The study also found that a basophil activation test (BAT) predicted OFC outcomes with 90% accuracy (p < 0.001), demonstrating strong potential as a clinical diagnostic tool.

The specific IgE test conducted at the six-month time point revealed significantly higher antibody levels to eggs and their components in infants who could not tolerate hard-boiled eggs compared to those who tolerated them.

Significance

The trial reports that introducing baked eggs into the diet of infants as early as four to six months of age and following the diet for six months can prevent the risk of developing egg allergy. Notably, infants who consumed baked eggs daily showed a significant reduction in their egg white IgE-to-total IgE ratio, a marker linked to improved tolerance, while those who avoided eggs maintained persistently high ratios.

In other words, the trial highlights that early and regular exposure to baked foods can help children develop tolerance to cooked foods later in life.

Two infants who could not tolerate baked eggs at baseline (during initial testing) developed severe allergic reactions (anaphylactic reactions) following an oral food challenge test. This highlights the need to perform this kind of test in hospitals with the necessary facilities to treat severe reactions.

Although most effective in diagnosing food allergies, the oral food challenge test often has serious consequences. In this context, the trial indicates that specific IgE tests and basophil activation tests can be considered useful predictors of oral food challenge test outcomes.

Notably, the trial finds a gradual reduction in the egg white IgE to total IgE ratio over the study period in infants who consumed baked eggs daily. In contrast, a persistently higher ratio has been observed in infants who consumed an egg-free diet. These infants reacted more to boiled eggs during the oral food challenge test at the six-month time point.

Collectively, these findings indicate that the daily intake of baked eggs helps reduce the egg white IgE to total IgE ratio, which in turn helps improve the tolerance to boiled eggs. The observed improvement in tolerance could be due to the immunomodulatory effect of baked foods, which minimizes the risk of allergic reactions.

While the study’s small sample size limits broader conclusions, its findings align with growing evidence supporting early allergen introduction. Longer-term studies are needed to determine whether the tolerance observed at six months persists into later childhood.

Overall, the trial provides valuable information for developing interventions to reduce food allergy risk in children and adolescents. Future studies with larger sample sizes are required for more conclusive interpretations.