Childhood Egg Allergies Decline 17% After Early Introduction Guidelines, Landmark Study Shows

After a dramatic shift in infant feeding guidelines that moved from delaying allergenic foods to introducing them early, the prevalence of egg allergy (search)Search disease among children fell by more than 17%, according to a new study published Monday in JAMA Pediatrics.

The study, based in Australia, analyzed data on more than 7,000 infants between 11 and 15 months old who had immunization visits at centers in Melbourne. The infants represented two cohorts: one with visits occurring between 2007 and 2011, before Australia updated its allergy prevention guidelines, and another with visits between 2018 and 2019, after the 2016 guideline update that recommended introducing egg and other food allergens in the first year of life.

"To our knowledge, this is the first study to show a population-level reduction in egg allergy (search)Search disease after the introduction of new infant feeding guidelines," said Jennifer Koplin, group leader of childhood allergy and epidemiology at the University of Queensland Child Health Research Centre (search)Search term and lead author of the study.

Dramatic shift in parental behavior

The data revealed a striking change in how parents introduced eggs to their infants. The proportion of infants introduced to eggs by 6 months of age more than doubled from about 25% in the 2007-2011 group to about 57% in the 2018-2019 group, after guidance had changed.

Correspondingly, the prevalence of egg allergy (search)Search disease decreased from 9.2% in the pre-guideline cohort to 7.6% in the post-guideline cohort — a 17.7% relative decrease, according to the study.

"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. 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 (search)Search disease."

Impact on high-risk infants with eczema (search)Search disease

Eczema (search)Search disease is a known risk factor for developing food allergies, and the researchers conducted a subgroup analysis specifically in infants with early eczema. The findings were even more pronounced in this population: the prevalence of egg allergy (search)Search disease decreased from 34.6% to 21.9%.

Scientists believe the link between eczema (search)Search disease and food allergy may be explained by how the immune system first encounters an allergen. "We know now that introduction of a food allergen to the gut, meaning the intestines, is going to teach the immune system that that food is safe," said Dr. David Hill, a pediatric allergist and immunologist at Children's Hospital of Philadelphia. By contrast, if the immune system first encounters an allergen through food particles contacting dry, broken skin, that will, for some children, "teach the immune system that that food allergen is dangerous."

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, elaborated: "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."

Evolving guidance and lessons learned

In the United States, recommendations for preventing food allergies have evolved dramatically. In 2000, the American Academy of PediatricsView company profile advised that infants at high risk avoid eggs until age 2. By 2008, the AAP updated its guidance to support introducing eggs by 6 months of age, citing "little evidence" that delaying introduction prevented allergies.

In an editorial accompanying the study, Dr. Aaron Carroll of AcademyHealth and Dr. Ron Keren of Children's Hospital of Philadelphia wrote: "The field issued recommendations that outran the evidence, and families lived with the consequences. We owe families an honest accounting of that."

They added: "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."

Implications for the United States

While the study was conducted in Australia, the findings may have relevance for the U.S. "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 (search)Search disease in the US," Koplin said.

However, the researchers noted that U.S. adoption rates lag behind. Only 15.5% of infants in the U.S. were introduced to egg before 7 months of age in 2021, compared with 57% in the study's 2018-2019 Australian cohort.

Egg allergy (search)Search disease affects an estimated 1.3% of children under age 5 in the U.S. Most children outgrow the allergy by age 16, and it is less common in adulthood. In people with egg allergy, the immune system overreacts to proteins in egg whites or yolks, potentially causing hives, respiratory symptoms, and sometimes anaphylaxis.

"It is exciting to see population level real-world evidence supporting early introduction of allergens," said Sung Poblete, CEO of the nonprofit Food Allergy Research & Education (search)Search term, who was not involved in the study. "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 (search)Search disease prevention at the population level."

The new study parallels recent research on peanut allergy. A landmark 2015 study found early peanut introduction reduced allergy risk, the NIH released updated guidelines in 2017, and a separate study published last year in Pediatrics found that rates of peanut allergy fell following the updated guidance.

"These findings highlight that guideline changes, when based on high-quality evidence and widely adopted, can lead to meaningful reductions in food allergy prevalence," Koplin said.