New York 
First peanuts, now eggs.

Doctors have reversed allergies in some children and teens by giving them tiny daily doses of problem foods, gradually training their immune systems to accept them.

In the best test of this yet, about a dozen kids were able to overcome allergies to eggs, one of the most ubiquitous foods, lurking in everything from pasta and veggie burgers to mayonnaise and even marshmallows. Some of the same doctors used a similar approach on several kids with peanut allergies a few years ago.

Don’t try this yourself, though. It takes special products, a year or more and close supervision because severe reactions remain a risk, say doctors involved in the study, published in Thursday’s New England Journal of Medicine.

“This experimental therapy can safely be done only by properly trained physicians,” says a statement from Dr Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, the federal agency that sponsored the study.

It didn’t work for everyone, and some dropped out of the study because of allergic reactions. But the results “really do show there is promise for future treatment” and should be tested now in a wider group of kids, said the study’s leader, Dr A. Wesley Burks, paediatrics chief at the University of North Carolina, Chapel Hill.

More than 2 per cent of young children have egg allergies, suffering wheezing and tight throats or even life-threatening reactions if they eat any egg, Burks said. Many will outgrow this by age 4 or 5, and more will by the time they are teens, but 10 to 20 per cent never do. The big worry is that these kids will eat eggs as an ingredient in a food they don’t realise contains them, and have a severe reaction. Training a child’s immune system to tolerate even small amounts of egg to prevent this was the goal of the study.