WASHINGTON: Elizabeth White's first encounter with peanuts — a nibble of a peanut butter cracker at age 14 months — left the toddler gasping for breath. Within minutes, her airways were swelling shut.

A mere fifth of a peanut was enough to trigger an allergic reaction. So it was with trepidation that her parents enrolled Elizabeth, at 4 1/2, in a groundbreaking experiment: Could eating tiny amounts of the very foods that endanger them eventually train children's bodies to overcome severe food allergies?

It just may work, suggest preliminary results from a handful of youngsters allergic to peanuts or eggs — and who, after two years of treatment, seem protected enough that an accidental bite of the forbidden foods is no longer a huge threat. "We're so lucky," says Carrie White, Elizabeth's mother.

Now 7, Elizabeth can safely tolerate the equivalent of seven peanuts. For the first time, the Raleigh, North Carolina, girl is allowed to go on playdates and to birthday parties without her parents first teaching the chaperones to use an EpiPen, a shot of epinephrine that can reverse a life-threatening reaction. "Our whole worry level is really gone."

Don't try this experiment on your own, warns lead researcher A Wesley Burks of Duke University Medical Center. Children in the study are closely monitored for the real risk of life-threatening reactions.

But if the work pans out — and larger studies are beginning — it would be a major advance in the quest to at least reduce severe food allergies that trigger 30,000 emergency-room visits and kill 150 people a year.

"I really think in five years there's going to be a treatment available for kids with food allergy," says Burks.