Egg allergies reduced by desensitization, study finds

12:20 PM, Jul 20, 2012   |    comments
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(USA TODAY) -- Children allergic to eggs are told to avoid the food completely. But in a promising new clinical trial, doing the exact opposite appears to have reduced -- and in some cases eliminated -- kids' egg allergies.

Researchers in today's New England Journal of Medicine report that 30 of the 40 egg-allergic children who ate small amounts of powdered egg white every day for 22 months became "desensitized" and experienced little or no allergic reaction.

After two years of treatment, 11 of the 44 (28%) were able to freely incorporate egg products into their everyday diet with no problem.

The federally funded study is the latest and most extensive to examine oral immunotherapy (OIT), an approach in which a person with food allergy consumes gradually increasing amounts of the food as a way to desensitize the immune system.

"Desensitization is not a new finding, although we're beginning to learn a lot of new things about it," says Marshall Plaut, chief of the National Institute of Allergy and Infectious Diseases Allergic Mechanisms Section and a study co-author. But this study is of particular interest, he says, because it involved a substantial number of children at five clinical sites across the country and because of the long-term effects.

At 36 months, 10 of 11 kids still in the study had no adverse reactions to eggs.

The findings illustrate "another possible outcome of treating kids with food allergy," says Plaut.

Besides avoidance, "we currently don't have an adequate treatment for food allergies," which can trigger severe and sometimes life-threatening reactions, says Wesley Burks, chair of the Department of Pediatrics at the University of North Carolina, Chapel Hill, and a lead author of the study.

A study published in 2011 found approximately 8% of U.S. children, or one out of 13, have a food allergy, nearly double previous estimates.

Researchers stress that oral immunotherapy is still experimental and should never be attempted at home because the risk of having a severe reaction is substantial. It's not even ready for broad-scale use in allergists' offices, says Stacie Jones, Chief of Allergy and Immunology at Arkansas Children's Hospital, the other lead author: "There's a lot of details to be worked out."

In the new NEJ study, 55 children ages 5 to 11 who had egg allergy were randomly assigned either to the treatment group (40 children), which received a daily dose of powdered egg whites, or the control group (15 children), which received a cornstarch placebo.

The dosage was gradually increased every two weeks until subjects were eating the equivalent of about one-third of an egg every day mixed into their regular food.

Clinicians exposed the children to oral food challenges (in which they ate increasing amounts of egg powder) at 10 months, 22 months and 24 months, with the maximum challenge equivalent to one egg. They passed the challenge if they had either no symptoms or only transient symptoms not directly observable by a doctor, such as throat discomfort. They failed if they had a symptom that could be observed by a doctor, such as wheezing.

After 10 months, none of the 15 who received the placebo passed the challenge, but 55% of those getting eggs did.

At 24 months, 28% of the original treatment group were able to eat eggs at will.

It's not clear why some patients responded better than others to the therapy, although "markers, such as skin prick testing results and egg-specific antibody levels, indicated a range of changes in patients' immune systems," Burks says.

Although many children outgrow egg allergies by age 5, the allergy and its symptoms, which can be mild to severe and affect skin, respiratory and gastrointestinal systems, can persist into adulthood, Jones says.

Egg allergies are a particular challenge, she says, because "eggs are so ubiquitous," often used for flavoring and binding in many processed foods. As a result, "It's very easy to have an accidental ingestion."

The findings "provide some hope that we may have a therapy in the future or a series of therapies that will help children and families navigating the land mines of food allergies do it a little bit better," Jones added.

(Michelle Healy, USA TODAY)

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