Gradual exposure to egg cuts allergy risk
NEW YORK (Reuters Health) - Gradual exposure to egg white over about two years can reduce and sometimes eliminate a child's allergy to the food, according to a new study.
Eleven of 40 children completely lost their hypersensitivity to eggs. Most showed a significant reduction in sensitivity, even if it faded one month after the researchers stopped exposing the youngsters to small amounts of egg protein powder.
More research is needed to improve the success rate and develop the safest procedure, said Dr. Robert Wood, director of allergy and immunology at Johns Hopkins Children's Center and one of the study's authors.
However, he told Reuters Health in a telephone interview, "We now believe the potential for a cure for food allergy is out there."
Wood warned parents against trying the technique with their children because of the potential danger.
"It's very risky," he said. "The starting dose of egg protein in this study was equal to one 80,000th of an egg. It cost $30,000 to buy a scale that could measure something that small."
The study, funded by the National Institutes of Health, was published Wednesday in the New England Journal of Medicine.
Dr. Matthew Greenhawt, research director at the University of Michigan Food Allergy Center, expressed guarded optimism.
Much more work is needed to refine the results, said Greenhawt, who was not involved in the work. For example, children with an extreme life-threatening reaction to eggs were not included in the test.
Still, "this trial gives hope to 15 million Americans affected by food allergy that a cure may one day be available," Greenhawt told Reuters Health by email, noting that "to date, there is no known cure for food allergy beyond avoidance."
The treatment is also being tested on children with allergies to peanuts and milk. "The results are quite similar," according to Wood, although they have not been published.
Nearly three percent of children age two and a half have some evidence of egg allergies, but they sometimes outgrow the sensitivity.
The children in the study ranged in age from five through 11. Using a technique known as oral immunotherapy, the researchers gave gradually higher doses of egg white powder, usually mixed in with food, to 40 children. Another 15, in a control group, received cornstarch placebo.
At the 10-month mark, all of the children still in the placebo group couldn't eat 5 grams of egg protein - the equivalent of half of a large egg - without having a reaction.
But 14 of the 35 children still in the treatment group (five had dropped out) had no allergic reaction; another eight had a minor one. After another year of treatment, 30 children ate 10 grams of egg protein with few or no symptoms.
"These children went from having serious allergic reactions after a single bite of an egg-containing cookie to consuming eggs with minimal or no symptoms," Wood said in a statement.
Those who passed that test then abstained from all egg consumption for at least a month to test how long the effect lasted; 11 were considered to be cured of their allergy after they consumed both the egg powder and a cooked egg.
One year later, 10 of the 11 were reportedly eating all the eggs and egg-containing products they wanted. The researchers lost track of the 11th child.
The children who were not permanently cured nonetheless were able to eat birthday cakes and smaller amounts of omelet, according to Wood. "It made their life a lot safer," he said.
But Greenhawt expressed concern about some of the reactions that were seen.
"Both mild as well as severe adverse events were reported in 25% of the doses," he said. "Additionally, several subjects withdrew because of experiencing an allergic reaction to the therapy."
He also cautioned that only kids between five and 12 years old and without a history of the serious allergic reaction known as anaphylaxis had been part of the study.
"This does not accurately represent the full population of egg-allergic children," Greenhawt said.
SOURCE: bit.ly/OkwXh7 New England Journal of Medicine, online July 18, 2012.
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