Ingrid Hein

November 12, 2016

SAN FRANSISCO — Although the evidence shows that allergenic foods — including peanuts, eggs, and milk — should be introduced in the first year of life, guidelines are lagging behind, said an allergist speaking here at the American College of Allergy, Asthma & Immunology (ACAAI) 2016 Annual Scientific Meeting.

Official guidelines to be issued early in 2017 will address only peanuts, recommending introduction when children are 4 to 6 months of age.

"There is now a large body of observation and trial data for other foods, including egg, that show that delaying the introduction of allergenic solids increases the risk of those particular food allergies," said Katrina Allen, MBBS, PhD, from the Murdoch Childrens Research Institute in Melbourne, Australia.

Policy changes are needed to help guide parents' decisions, she said. In fact, there is evidence showing that changes to policy — namely, infant-feeding guidelines — mirror the rise in the incidence of food allergies.

"Even if this is due to reverse causation — those at highest risk of food allergies are the ones most likely to avoid allergenic foods, such as peanut, egg, and cow's milk — the timely introduction of solids that are allergenic is unlikely to be harmful," said Dr Allen. "If you look at earlier introduction, there's a good trend down."

Not everyone agrees on exposure amount and timing in the case of egg allergy.

In a recent trial, researchers looked at the early introduction of allergenic foods in breast-fed children (N Engl J Med. 2016;374:1733-1743). The prevalence of any food allergy was significantly lower in the early-introduction group than in the standard-introduction group (2.4% vs 7.3%; P = .01), as was the prevalence of peanut allergy (0.0% vs 2.5%; P = .003) and egg allergy (1.4% vs 5.5%; P = .009). And a study Dr Allen was involved in, which introduced cooked egg in small amounts, showed that early introduction reduced allergy (J Allergy Clin Immunol. 2010;126:807-813).

However, in a German study, where greater amounts of egg were introduced at 4 to 6 months, early exposure increased the risk for life-threatening allergic reactions (J Allergy Clin Immunol. Published online August 12, 2016).

And in the STEP study, there was no change in the number of food allergies in 1-year-old children when egg was introduced early (J Allergy Clin Immunol. Published online August 20, 2016). However, that did not take into account high-risk infants, particularly those with eczema, who are known to have a higher incidence of egg allergy and are likely to see a much greater benefit from the early introduction of egg.

"Although the exact optimal window of introduction has not been pinned down, we do know that exposure to these foods in the first year of life is important for all babies, irrespective of family history risk," said Dr Allen.

The new peanut guidelines — coauthored by Amal Assa'ad, MD, from the Cincinnati Children's Hospital, who is chair of the ACAAI food allergy committee — will recommend that children with no eczema or egg allergy can be introduced to peanut-containing foods at home, according to the family's preference. And for children with mild to moderate eczema who have already started solid foods, the guidelines say that peanut-containing foods can be introduced at home at around 6 months of age, without the need for an evaluation.

However, the guidelines caution, peanut-containing foods should not be the first solid food an infant tries, and an introduction should be made only when the child is healthy. The first feeding should not happen when the child has a cold, is vomiting, or has diarrhea or another illness.

For eggs, there is no official recommendation as of yet. "We won't know if it works unless we tell parents to force-feed their child eggs — give them this much for this long," Dr Assa'ad said after her presentation.

For kids with a rash who are throwing up and end up in emergency department, "we don't know the intervention yet," she said.

Children with eczema are far more likely to have an egg allergy, and egg allergy supersedes peanut allergy. "It's a real problem," said Dr Assa'ad. After the first bite of egg, if a child reacts, most parents don't give their child egg again, they go to an allergist, and at that point, they can decide to have an intervention with early introduction.

It's important to remember that different populations and different cultures behave differently, she said. "Making policies and recommendations based on studies not done in United States is not the best way to go. We need our own studies here."

Still, she said, the infants who really need the intervention of early introduction are those with severe eczema.

"It's a matter of identifying them. But we need to direct them and hold their hand in this — it's not an easy intervention," she explained. For high-risk egg allergies, early intervention could mean introducing egg at 2 months of age, which poses obvious difficulties.

More Dirt, Dogs, and Sun; Less Bathing

The early introduction of allergenic foods is not the only policy that needs to be changed to lower the incidence of food allergies, Dr Allen told Medscape Medical News. Other factors, particularly environmental factors — mostly written up in observational studies — are contributing to an increasing intolerance to allergenic foods. Policies advocating that kids "get down and dirty," have more exposure to dogs, and bathe less are also warranted.

In a literature review published last year, Dr Allen and her colleagues report that recent studies are showing an increased risk for peanut allergy in people with a damaged skin barrier, like those presenting with eczema early in life (Curr Opin Allergy Clin Immunol. 2015;15:409-416).

Children with extreme eczema for at least 12 of 30 days in the first 6 months of life, have double the risk of developing food allergies (J Allergy Clin Immunol. 2015;135:164-170). This, Dr Allen said, is likely related to detergents and soaps breaking down the skin barrier. "The immune system sees it as harmful," she told Medscape Medical News. "Babies don't crawl, so exposure to microbes may be different early in life, compared with later."

"With rising rates of eczema, we may be overbathing our babies, particularly with harsh detergents. We should consider the public health message: Don't soap the baby!" she advised.

Dr Allen was also involved in a review that summarized the leading hypotheses to explain the increase in food allergy as "the 5 Ds": dry skin (eczema), diet, dogs, dribble (shared microbial exposure), and vitamin D (J Allergy Clin Immunol Pract. 2016;4:215-220).

Dr Allen and Dr Assa'ad agree that delaying the introduction of foods such cow's milk and egg until after 12 months is harmful. Guidelines should encourage families to introduce these foods in the first year of life, once solids have commenced at around 6 months, but not before 4 months.

But it's not always easy. "Babies don't read guidelines; they eat when they're ready," Dr Allen pointed out.

Still, new policy and publicity about the LEAP trial is getting parents to allergists earlier. "I find that since awareness of this study is up, mothers with infants are coming to see me, especially when there are siblings with allergies," said Terri Moncrief, MD, from the Allergy and Asthma Centre of Dayton in Ohio.

"I like to err on the side of early introduction of a lot of foods. The LEAP trial told us early is protective," she told Medscape Medical News. "Most of the time, children are able to tolerate the foods."

"It's the kids who have early egg allergy combined with eczema that I'm most careful with," she added.

Dr Allen, Dr Assa'ad, and Dr Moncrief have disclosed no relevant financial relationships.

American College of Allergy, Asthma & Immunology (ACAAI) 2016 Annual Scientific Meeting. Presented November 12, 2016.

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