Giving kids with egg allergy tiny amounts of egg-white powder each day under a doctor’s care could help their immune systems to overcome the allergic reactions, a U.S. study suggests.
Eggs are an ingredient in foods ranging from veggie burgers to marshmallows. Avoiding eggs is a constant responsibility for parents and caregivers and leaves patients vulnerable to unintentional exposure and potentially life-threatening anaphylaxis.
It's estimated almost three per cent of children in the U.S. are diagnosed with an egg allergy by the time they are 2½ years old. The allergy can lead to wheezing, hives, or dangerous swelling at the back of the throat and trouble breathing when exposed to eggs. About 10 to 20 per cent of sufferers never outgrow the allergy.
In this week's issue of the New England Journal of Medicine, doctors said 11 out of 40 children who received "oral immunotherapy" were able to eat some egg under medical supervision without showing symptoms such as wheezing.
Doctors have used the same treatment approach to desensitize people allergic to peanuts and milk.
"Currently, the only way to prevent these reactions from occurring is for these children to avoid foods that contain eggs," said Dr. Anthony Fauci, director of the U.S. National Institute of Health’s National Institute of Allergy and Infectious Diseases, which funded the research.
"While this relatively small study provides encouraging new information, it is important for the public to understand that this experimental therapy can safely be done only by properly trained physicians," he cautioned in a release.
The study included 55 children aged 5 to 11. Of these, 40 were randomly assigned to egg therapy with egg-white powder and 15 to cornstarch as a placebo.
The children were gradually exposed to increasing amounts of egg white power until they were eating about a third of an egg daily.
After 10 months of therapy, 55 per cent of those receiving oral immunotherapy passed the food challenge and were considered desensitized compared with none in the placebo group, said study author Dr. Scott Sicherer, a professor of pediatrics at Mount Sinai School of Medicine in New York.
Daily egg exposure needed to maintain tolerance
The last step of the experiment tested whether participants could keep up their tolerance.
Those who passed the food challenge at 22 months then stopped the treatment and avoided all eggs for six weeks. By that time, 75 per cent who received the treatment were desensitized and able to eat 10 grams of egg white powder and a whole cooked egg without showing symptoms, the researchers found.
"We found that oral immunotherapy provides protection in a majority of children with egg allergy by raising the reaction threshold and represents a highly promising therapeutic intervention for food allergy," the study's authors concluded.
They called the approach "relatively safe," with reactions to dosing mild and less than one per cent considered moderate.
The fact that most children lost some of their tolerance after only a month of abstinence underscores the importance of daily exposure to an allergen to maintain tolerance, the researchers said.
Before oral immunotherapy could be recommended, the risks needed to be better defined compared with avoiding the food a child is allergic to, and the best dose needs to be determined, they added.
The treatment worked for 10-year-old Nicholas Redmond of North Carolina, who now has some egg every day to keep up his tolerance. His father, Chris Redmond, sees the irony. "You spend 2½ years avoiding eggs" and now he needs to get some of the food often.
No children were enrolled in the study if they had severe anaphylaxis such as low blood pressure after eating egg.
About 91 per cent of participants, including Nicholas, also had at least one other food allergy. In his case, he’ll start the oral immunotherapy for a peanut allergy next month.