One out of every 13 children has a food allergy, but the affliction still regularly stumps doctors. As Kari Nadeau, director of the Stanford Alliance for Food Allergy Research, told Terry Gross in April on Fresh Air, researchers still don't understand what "flips the switch between a food allergen versus a food nutrient in children."
While the origins of food allergies remain unclear, scientists are learning how to treat them. An emerging body of research shows that kids may be able to kick a food allergy by regularly consuming — under doctor supervision — a small amount of the food every day for a set amount of time, at a dose that increases over time.
The idea behind "oral immunotherapy" is that you can teach an allergic child's immune system to ignore the food protein that pushes it into overdrive. It's the same principle that has dictated how people with environmental allergies have been treated for decades – they are given shots with small amounts of the allergen.
Preliminary experiments involving milk, peanuts and other allergenic foods have shown this strategy works. The most common problematic foods among kids with allergies are peanuts (25 percent), milk (21 percent) and shellfish (17 percent). More than a third of kids with food allergies are allergic to more than one food.
Robert Wood, director of the Division of Pediatric Allergy and Immunology at the Johns Hopkins Children's Center, has conducted some of the studies of milk and other allergens. He says that the success of the early trials suggested that the benefits of oral immunotherapy would last.
Not so, according to the first long-term study of children allergic to milk who received the treatment.
Wood and his colleagues tracked 32 children who'd received oral immunotherapy for milk allergy in two separate studies at Johns Hopkins and Duke University. Three to five years after the treatment, eight children remained symptom-free long term, but 12 other children were once again experiencing frequent symptoms when they consumed milk. Six children had serious allergic reactions, and three of them reported having to use injectable epinephrine — or an EpiPen — at least once to deal with a life-threatening allergic reaction. The results appear online in the Journal of Allergy and Clinical Immunology.
"At the end of our first study, we thought the milk allergy might be completely cured," Wood tells The Salt. "But some kids went back to avoiding milk and then had very severe reactions."
Three to five years after the treatment, Wood says it was hard for most of the kids to keep milk in their diet on a regular basis. "So we think this lack of continuous exposure is the main underlying factor of why people lose protection to the allergen," he says.
So how long might people have to be exposed to oral immunotherapy before kicking a food allergy? Researchers are still figuring that out, Wood says. "I would guess that it ranges from six months to life, but that a majority [of people] could get there with five years of consistent intake," Wood says.
He and his colleagues also want to look at whether kids get more lasting protection if, in the initial treatment, they receive higher doses of the allergen over a longer period of time.
But Wood stresses that this is definitely not something any child — or parent — should try at home. "This treatment is not ready for prime time," he notes. Kids should only receive oral immunotherapy if they're enrolled in a research trial approved by the Food and Drug Administration.
If you're curious about food allergies and oral immunotherapy research, check out the excellent piece on Dr. Kari Nadeau's work in The New York Times Magazine.