LOS ANGELES – Among infants at risk for allergic disease, egg introduction at 4 months cuts the risk of egg sensitization at 12 months by about half, according a randomized, placebo-controlled, double blind trial from Australia.
“This is what we hoped to find.” Introducing egg early “is certainly safe, and it may promote tolerance,” said senior investigator Dr. Dianne Campbell, professor and chair of pediatric allergy and clinical immunology at the Children’s Hospital at Westmead, which is affiliated with the University of Sydney.
Dr. Dianne Campbell
Four-month-old children were randomized to 350 mg of pasteurized raw whole egg powder or – as a control – rice powder sprinkled once daily on their weaning food until month 8, at which time parents in both groups were encouraged to add eggs to their children’s diets. At least one of each child’s parents had a history of atopic disease, including asthma, eczema, hay fever, or food allergy. Even so, all of the infants had negative (less than 2 mm) skin prick tests (SPTs) at baseline. Compliance by parent diary was 89% in the rice and 81% in the egg groups.
At 12 months, SPTs were positive (3 mm or more) for whole egg in 25 of 122 (20%) children in the rice group, but only 13 of 122 (11%) in the egg group (odds ratio, 0.46; 95% confidence interval, 0.22-0.95; P = .03). Whole egg IgG4 and IgG4/IgE ratios to egg, ovalbumin, and ovomucoid were also higher in the egg group, indicating developing tolerance (P less than .0001 for each).
About 10% of the children originally in the egg group broke out in hives after their first few doses, and were withdrawn from the study. “This intervention may not be for everybody. There will be individuals who react” and it’s impossible, at this point, to predict who they will be. “We cannot prevent allergy in everyone,” said lead investigator Dr. John Tan, a pediatric immunologist at the hospital.
Dr. John Tan
Overall, however, early introduction was safe. There was no anaphylaxis in the trial, and no cardiovascular or respiratory complications. Rates of eczema and peanut allergy were similar at 12 months between the two groups, meaning that early egg introduction did not increase the risk of atopy.
The findings echo results from several recent pediatric egg allergy studies, as well as findings from recent peanut trials. Slowly, it’s becoming clear that delaying the introduction of at least some allergenic foods – a common practice for years – doesn’t prevent allergies and may, in fact, promote them.
Despite those findings, there remains “a big disconnect between the [new] research and what we [still] recommend” in Australia, the United States, and elsewhere. Delaying food introductions was medical “dogma for 20 years, from highly esteemed societies,” and it corresponded with a marked increase in food allergies, but “it’s very hard to turn these things around,” Dr. Campbell said at the American Academy of Allergy, Asthma, and Immunology annual meeting.
The Australian government is reworking its infant feeding guidelines to incorporate the new evidence. “Our revised guidelines will say that there’s strong evidence for peanut and moderate evidence for egg” in favor of early introduction in children who are not sensitized by 4 or so months old, she said.
The trial was powered to detect differences in SPT, not actual egg allergies, which were diagnosed in 13 children (11%) in the rice group and eight (7%) in the egg group; the difference was not statistically significant. “Not all kids who are sensitized will be allergic,” she noted.
The study groups were well matched; there were about equal numbers of boys and girls in each, and, in both groups, about 15% of children were exposed to second hand smoke at home and almost all were breastfed.
The work was funded by the Australian government, among others. The investigators have no disclosures.