Childhood egg allergies fall as early introduction becomes more common, new study finds

By Jacqueline Howard, Diana Anos, CNN

(CNN) — Parents used to be advised to keep allergenic foods like eggs away from babies, especially if allergies ran in the family. But based on recent and evolving evidence, the advice is now almost the opposite – and new research suggests the shift in guidance is paying off.

After the drastic change in guidance to no longer keep allergenic foods away from babies until 1 to 3 years of age and instead introduce them by 6 months of age, the prevalence of egg allergy among children fell by more than 17% in a new study published Monday in the journal JAMA Pediatrics.

“These findings highlight that guideline changes, when based on high-quality evidence and widely adopted, can lead to meaningful reductions in food allergy prevalence,” Jennifer Koplin, group leader of childhood allergy and epidemiology at the University of Queensland Child Health Research Centre and lead author of the new study, said in an email.

The study, based in Australia, adds to the growing body of evidence supporting that the latest guidance is not only considered safe but is also linked with a meaningful decline in egg allergies among children. The findings can offer some reassurance to parents who may still be uncertain about when to introduce potentially allergenic foods to their babies.

“To our knowledge, this is the first study to show a population-level reduction in egg allergy after the introduction of new infant feeding guidelines,” Koplin said.

Cracking the allergy puzzle

In the United States, recommendations for preventing food allergies among children have evolved dramatically over the past few decades, leaving some parents wondering which guidance to trust and whether following the latest advice is truly safe.

In 2000, the American Academy of Pediatrics advised that infants at high risk for allergies, including those with eczema or a family history of food allergies, avoid eggs until age 2. The thinking at the time was that delaying exposure might help prevent allergic reactions.

But as more evidence emerged, that guidance began to change. In 2008, the AAP updated its guidance to support introducing eggs by 6 months of age, citing that there is “little evidence” that delaying the introduction of allergenic foods prevented allergies.

Research increasingly supported that change: introducing eggs earlier appeared to reduce the risk of developing an egg allergy.

Globally, allergy prevention guidelines also had been updated. In Australia, infant feeding guidelines for allergy prevention were updated in 2016 to recommend introducing egg and other food allergens in the first year of life to reduce the risk of food allergy, according to the new study.

It is not unusual to see evolving guidance in medicine – but “the lesson we should take from this story isn’t only that science self-corrects. It’s that the original error was avoidable,” Dr. Aaron Carroll, of the nonprofit AcademyHealth, and Dr. Ron Keren, of Children’s Hospital of Philadelphia, wrote in an editorial accompanying the new study in JAMA Pediatrics.

“The field issued recommendations that outran the evidence, and families lived with the consequences. We owe families an honest accounting of that,” Carroll and Keren wrote in the editorial.

“And we owe it to the next generation of patients to hold ourselves to a higher standard—one that includes evidence grading so families understand the degree of certainty behind a recommendation, mandatory reassessment at regular intervals, and a commitment to funding the trials that can fill evidentiary gaps before guidance is issued rather than decades after,” they wrote. “When we do not have the evidence to support a recommendation, we should say so, clearly and without embarrassment, rather than fill the silence with confident advice that turns out to be wrong.”

The new study parallels recent research examining how the same shift in peanut allergy guidance has led to a reduction in the prevalence of peanut allergy among children. A separate study published in the journal Pediatrics last year found that rates of peanut allergy fell following the publication of updated guidelines.

Eggs earlier, fewer allergies

The new study included data on more than 7,000 infants between 11 and 15 months old who had immunization visits at centers in Melbourne, Australia. The infants represented two groups: some had visits that occurred between 2007 and 2011, before the guidelines in Australia were updated, and the others had visits that occurred between 2018 and 2019, after the update.

For both groups – those with visits before and after the update – parents completed questionnaires and infants were tested for egg allergy. The researchers then analyzed each group, taking a close look at what age each infant was introduced to eggs and how many were found to have an egg allergy.

“We began this study hoping to see a reduction in egg and other food allergies after the introduction of the 2016 guidelines,” Koplin said.

“However, we were unsure to what extent parents would adopt these recommendations, or whether this would translate into a measurable reduction in food allergy,” she added. “We were therefore encouraged to find that most parents had followed the new guidelines, and importantly, that this was associated with a clear reduction in egg allergy,”

The data showed that the proportion of infants introduced to eggs by 6 months of age more than doubled from about 25% in the 2007-2011 group, before guidance changed, to about 57% in the 2018-2019 group, after guidance had changed.

The researchers also found that the prevalence of egg allergy decreased from 9.2% in the 2007-2011 group, before guidance changed, to 7.6% in the 2018-2019 group, after guidance changed – which corresponds to a 17.7% relative decrease, according to the study.

Eczema is a known risk factor for developing food allergies, and when the researchers analyzed the data specifically in infants with early eczema, similar findings emerged. In infants with early eczema, the prevalence of egg allergy decreased from 34.6% to 21.9%, the study showed.

“It is exciting to see population level real-world evidence supporting early introduction of allergens,” Sung Poblete, CEO of the nonprofit Food Allergy Research & Education, who was not involved in the study, said in an email.

“The recommendation to introduce allergenic foods early and often has been widely adopted, and this study provides evidence that these practices are translating into impactful benefits for egg allergy prevention at the population level,” Poblete said.

Egg allergy in the US

While the new study was conducted in Australia, the findings may shed light on trends in the United States.

“In the United States, professional bodies such as the American College of Allergy, Asthma and Immunology and the American Academy of Allergy, Asthma & Immunology similarly recommend introducing egg from around 6 months of age. Given this, we would expect a similar reduction in egg allergy in the US,” Koplin said.

But the researchers also noted that, in the US, rates of timely egg introduction remained relatively low compared with Australia – with only 15.5% of infants in the US introduced to egg before 7 months of age in 2021 compared with 57% in the study’s 2018-2019 group, after guidance had changed.

Egg allergy has become one of the most prominent allergies in children. In the US, it’s estimated to affect about 1.3% of children under age 5. By age 16, most children tend to outgrow their egg allergy and by adulthood, the allergy is less common.

In people with egg allergy, the immune system overreacts to proteins found in egg whites or egg yolks. This can cause serious allergic symptoms, including hives, respiratory symptoms and sometimes, anaphylaxis, a life-threatening allergic reaction that can involve tightening of airways.

Early introduction is helpful to reduce the risk of allergy because, “the body’s immune system is at the root of allergy,” Dr. Scott Sicherer, professor of pediatrics and director of the Jaffe Food Allergy Institute at the Icahn School of Medicine at Mount Sinai in New York, said in an email.

“The immune system is ready to learn about foods in a helpful and normal way when the food is eaten and enters the gut. In that context, the immune system typically learns to recognize and intelligently accept the food. But if the gut immune system is not seeing the food, it is not learning,” Sicherer said.

“At the same time, if the food is around the baby it is a part of the environment, and may be touching baby skin and in the air being inhaled. Exposure to the skin or by inhalation could trick the immune system to think the food is an invader to be attacked,” he said. “In particular, babies with eczema have a poor skin barrier and skin inflammation, and so if they are not eating the food early, their skin immune cells may be especially ready to see that food in the wrong way.”

How to introduce babies to eggs

The new study’s finding that more people introduced egg to their baby by six months after the guidance changed reveals how updated guidelines can “truly have an impact,” said Dr. Elizabeth Lippner, an attending physician in the division of allergy and immunology at Lurie’s Children’s Hospital of Chicago, who was not involved in the study.

“Hopefully this is a sign that similarly in our country, and populations that I treat, people will also listen to these recommendations and follow these trends, and we certainly are seeing that in our clinics,” Lippner said about the United States.

She added that while doctors want children to be introduced to eggs early, parents should make sure that their children are ready to safely ingest the food, such as ensuring they can control their own head and neck, they open their mouth when you offer food, they sit up alone or with support, and they bring objects to their mouth and show swallowing cues.

Parents also should take the time to monitor children for any allergy symptoms. It’s important to also talk with your infant’s pediatrician about when and how to introduce solid foods.

Introducing foods before 4 months is not recommended, according to the US Centers for Disease Control and Prevention.

“Whether egg, peanut or other common allergens, an infant has to be developmentally ‘ready’ to manage something other than liquids and infant-safe forms of food, including of allergens, must be used,” said Sicherer, author of “The Complete Guide to Food Allergies in Adults and Children,” who was not involved in the new study.

“Allergens are not the typical ‘first foods,’ rather grains, fruits, vegetables are more typical, but once the infant shows they can manage solids like purees, then egg, peanut and other allergens can be incorporated with careful preparation,” Sicherer said in the email.

“For example, peanut butter is a choking hazard but it can be smoothed out into apple sauce or oat cereal. Egg has to be cooked well,” he said, “and then mashed well and pureed into food like apple sauce or infant cereal avoiding chunks that can be a choking hazard.”

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