Australian research shows earlier introduction to egg is associated with a decrease in allergy development, emphasising the importance of proper guideline implementation.
“Can I offer you a nice egg in this trying time?” – Frank Reynolds, It’s Always Sunny in Philadelphia.
Australia’s infant feeding guidelines were updated in 2016, recommending that a variety of food allergens were introduced in the first 12 months of an infant’s life to prevent the development of food allergies. Many children were introduced to certain foods, such as eggs, nuts, and seafood, at an earlier age after the guidelines were revised, but it is unclear whether the changes have translated to a reduction in allergy prevalence.
Now, new research from the University of Queensland and the Murdoch Children’s Research Institute suggests that the prevalence of egg allergy has declined on the back of effectively implementing guidelines that promoted earlier exposure to potential allergens.
“This study aimed to estimate the change in population prevalence of egg allergy after a guideline update recommending earlier introduction of egg into the infant diet, both in the general population and in predetermined subgroups of infants at high risk,” the researchers wrote in JAMA Pediatrics.
“This study provides population-level evidence that updated infant feeding guidelines recommending earlier introduction of egg led to measurable reductions in the population prevalence of egg allergy.
“The findings suggest that guideline updates informed by randomized trial evidence may be associated with a reduction in food allergy prevalence when implemented effectively.”
Lead author Associate Professor Jennifer Koplin, from the University of Queensland’s Child Health Research Centre, said that Australia had one of the highest rates of food allergy in the world, and that egg allergy was one of the most common food allergies in young people.
“To our knowledge, this is the first study to show a reduction in egg allergy after the introduction of new infant feeding guidelines at a population level. Most parents followed the guidelines, and these results provide reassurance that this advice will help reduce the chance of their child developing an egg allergy,” she told media.
Researchers compared data from two previous population-based studies designed to explore food allergy in children, the HealthNuts study (which ran between 2007 and 2011) and the EarlyNuts study (which ran between 2018 and 2019). Both studies involved questionnaires on allergy history and infant feeding, skin prick tests (SPTs), and oral food challenges (OFCs).
Egg allergy was defined as a positive OFC result, a reaction to egg within the last month that was consistent with OFC-stopping criteria, or anaphylaxis to egg since birth in infants with a SPT wheal of at least 2mm.
Data for 7209 infants across the two studies were included in the analysis – 5276 from the 2007-2011 study and 1933 from the 2018-2019 study. The median age of infants was similar (12.4 versus 12.5 months), as was the proportion of males (50.8% versus 51.8%) and the proportion of families who owned a dog (30.5% versus 31.2%).
Infants in the later cohort were introduced to egg at a younger age, first receiving egg at a median (interquartile range) age of 6 (6-8) months compared to 8 (6-10) months in the earlier cohort. Similarly, the proportion of infants who had been introduced to egg by six months of age increased from 25.4% in the 2007-2011 cohort to 57.3% in the 2018-2019 cohort. The proportion of infants who were not introduced to egg until after their first birthday decreased from 10.2% to 4.0%.
The raw prevalence of egg allergy was 8.8% (95% confidence interval 8.1%-9.6%) in the 2007-2011 study and 8.2% (6.8%-9.7%) in the 2018-2019 study. After accounting for missing data, the prevalence was 9.2% in the first cohort and 8.3% in the second cohort. Further standardisation of the 2018-2019 prevalence estimates to account for how risk factors were distributed in the 2007-2011 study further refined the prevalence to 7.6% (6.2%-9.0%). This equates to a 1.6% adjusted absolute decrease and 17.7% relative decrease compared with the 2007-2011 cohort.
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A subgroup analysis also showed a significant decrease in egg allergy among infants with early eczema (a parent-reported diagnosis of eczema in the first six months of life that had been managed with topical steroids) between the two studies (adjusted estimate 21.9% versus 34.6%). No association was seen in infants without early eczema (both estimates 5.6%).
Associate Professor Rachel Peters, the study’s senior author from the Murdoch Children’s Research Institute, said eczema was a known risk factor for food allergies.
“The introduction of the 2016 guidelines was a major change from most advice given in the 1990s and early 2000s which recommended parents delay giving eggs and other allergenic foods until 1-3 years of age if there was a strong family history of allergy,” Professor Peters told media.
“Current advice from the Australasian Society of Clinical Immunology and Allergy, based on the latest available evidence, is to introduce well-cooked egg and smooth peanut butter soon after a baby starts eating solid foods, usually around 6 months of age.’’
The researchers proposed that a high uptake of the updated food introduction guidelines was vital to the decrease in egg allergy prevalence.
“Implementation programs in Australia such as Nip Allergies in the Bub and high awareness of guidelines among maternal child health nurses, who have regular engagement with families and are a primary source of infant feeding advice, may contribute to the high uptake,” they wrote.
“[But] uptake was lower in families with parents born outside Australia, suggesting a need for targeted messaging to reach these communities.”
Professor Koplin said that egg allergy remained common despite the reduction shown in the current study.
“Some babies can still develop food allergy despite following the guidelines, and further research is underway and needed, to find other prevention strategies. But we hope these findings provide reassurance to parents to continue following the current recommendations.”
