Feeding eggs to a child who’s allergic sounds criminal, but a recent study finds that the exposure could actually cure them — or at least lessen their allergic reactions.
The strategy, called oral immunotherapy, involves feeding 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. So, parents, don’t try this at home.
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 5 g 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 10 g 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 10 g 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.”
The Johns Hopkins researchers, along with other groups, also conducted the previous research on oral immunotherapy for peanut and milk allergy. “Even though the studies are all small and you can’t compare them directly, the impression is that the results are extremely similar for milk and peanuts as they were for eggs in this study,” says Wood. “Most children do tolerate the treatment and most children do build up a significant level of protection. Somewhere around a quarter or a third of them appear to be really cured of the allergy.”
Dr. Wood estimates it will take another 5 to 10 years before oral immunotherapy can be offered for the general public. Larger studies still need to be done, and each treatment can take about two to three years to complete. “As the studies look more promising, people are literally beating down our doors to be in the next study,” says Dr. Wood. “Partly because food allergies are so common and partly because our results look promising.”
About 4% of U.S. children have some kind of food allergy — nearly 3% develop an egg allergy before age 3 — the authors note. Some kids will eventually outgrow their allergies, but for many they last a lifetime, and for now, the only adequate treatment for these kids is total avoidance. The new findings offer hope that there’s another way. “Right now we are focusing on kids with severe and persistent allergies, but in the long run we want to be able to individualize this treatment,” says Dr. Wood.
The study is published in the New England Journal of Medicine.