20 Jul 2012 Can eating eggs cure an egg allergy?
Oral immunotherapy is in the news again as a possible solution to food allergy. It involves the feeding of the allergy-producing food over time, in gradually increasing doses, in order to coax the immune system to tolerate it with few or no reactions. Previous studies have suggested that it works with common childhood allergens like milk and peanuts — and now with eggs, too.
The authors of the new study from the Johns Hopkins Children’s Center caution that the treatment is still considered experimental, however, and should be confined to the lab.
The study involved 55 children aged 5 to 11 who were allergic to eggs: 40 received oral immunotherapy, consisting of increasing doses of egg-white powder, and 15 got a cornstarch placebo over 10 months. At the end of the 10 months, the kids participated in an oral food challenge by eating 5g of egg protein, equivalent to about half a large egg, under medical supervision. (At this point, five kids in the immunotherapy group and two in the placebo group had dropped out.)
Twenty-two of the 35 children remaining in the immunotherapy group were able to eat the protein with fleeting symptoms — 14 of them with no symptoms — and passed the 10-month test. None of the children in the placebo group passed.
The 35 kids who received egg immunotherapy continued onto the maintenance phase of the experiment, consuming small doses of egg-white protein daily for 22 more months. At the end of 22 months, they underwent another oral challenge, this time with 10g of egg protein, as much as in one large egg. Thirty out of the 35 children passed the challenge.
After the 22-month challenge, those who passed then entered an abstinence period — 4 to 6 weeks of no egg consumption at all — and faced one final food challenge consisting of 10g of egg-white protein and a whole cooked egg. Eleven children passed the test with no symptoms, meaning they were cured of their allergy. Even a year later, the researchers found that these kids were eating eggs and egg-containing products as often as they wished, without allergic symptoms.
The rest of the kids were able to eat egg after the abstinence period with mild symptoms, but they had lost some of their tolerance, underscoring the importance of consistent exposure to desensitize the immune system. Still, even if children are not fully cured of their allergies, any amount of increased tolerance to food allergens helps, the researcher say, since it reduces the risk of severe reaction to accidental exposure, at restaurants and parties, for example.
“This kind of study really demonstrates that even though everyone didn’t get cured from their allergy, there was a big benefit from the treatment,” says Dr Robert Wood, director of allergy and immunology at the Johns Hopkins Children’s Center. “I think the greatest takeaway is that there really is help out there and food allergies can be a treatable condition.”