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Small doses of peanut protein, given for months under medical supervision, can desensitize children with peanut allergy, reducing the risk of a reaction if they accidentally eat peanuts, according to a new study.
In other new research, scientists say they have found a way to predict which children are likely to outgrow their allergy to peanuts.
Both studies were presented Saturday at the 2007 Annual Meeting of the American Academy of Allergy, Asthma and Immunology in San Diego.
Peanut allergies affect about 1% of the U.S. population, according to the Academy.
Reactions can range from mild to severe, even leading to anaphylaxis, a potentially fatal response that can cause breathing problems and loss of consciousness.
Traditional advice for food allergies was to simply avoid the food.
But avoiding all peanut-containing foods can be difficult and accidental ingestion often occurs, says Scott David Nash, MD, allergy fellow at Duke University and an author of the desensitization study.
For years, allergists have used immunotherapy, or allergy shots, to help children with allergies to insect stings and nasal allergies to non-food substances, for example.
With immunotherapy, tiny amounts of the allergens are injected until tolerance develops.
So Nash's team decided to try oral immunotherapy for peanut allergy problems, giving eight children with known peanut allergy escalating doses of peanut protein? in the form of a flour mixed into applesauce or other food.
"We are the first to do a trial of oral immunotherapy for peanut allergy," he tells WebMD.
The treatment included three phases: one day in the medical center, with increasing doses given throughout the day; a home phase lasting three or four months that involved daily, escalating doses; and a home maintenance phase in which the daily dose was 300 milligrams, about the equivalent of one peanut.
The maintenance phase lasted up to 18 months, depending on how much peanut protein the child tolerated.
At the end of the study, which seven children completed, Nash's team gave the children a "food challenge" to peanut flour, exposing them to up to nearly 8 grams, or the equivalent of more than 13 peanuts.
"Most [five of seven] tolerated the equivalent of 13 peanuts at the food challenge at the end of the study," Nash says.
Immune system changes from the start to the end of the study showed growing tolerance to the peanut protein, he says.
"What we would like to have happen is for their food allergy to go away," Nash says.
For now, however, he says, "We have essentially proven they can tolerate an accidental ingestion. We think our patients now are at reduced risk for anaphylaxis."
"No one should try this at home," Nash cautions. The concept is still in the research phases, and Nash says it's difficult to say when allergists might begin adopting the practice.
Parents in the study were told to contact the center if they suspected reactions; most reactions occurred in the clinic, not at home, Nash says.
More research is needed, he says, to prove the concept safe and effective.
Similar research is being done with egg immunotherapy. Wesley Burks, MD, another author of the peanut immunotherapy study, has done a similar study on egg allergies, Nash says.
When parents find out their child is allergic to peanuts, they always ask the same question, says Katie Allen, MD, PhD: "Are they going to be one of the 20% who grow out of it?"
Allen is a pediatric gastroenterologist and allergist at the Murdoch Children's Research Institute at the Royal Children's Hospital in Melbourne, Australia.
Until recently, doctors could only guess.
Now, Allen has found some good predictors by looking at skin prick test results.