They May Be Dietary Staples, But Milk And Eggs are also the most common triggers for childhood allergies. And although researchers used to believe that most milk and egg allergies would disappear by the time children reached age 3, new research suggests that fewer kids are outgrowing them — and the ones who are, take longer to do it.

A 13-year study performed at Johns Hopkins Children's Center traced allergic reactions in 1,000 children and found that even though tolerance for milk and eggs increased with age, only 20 percent of subjects outgrew milk allergies by age 4, while 79 percent had done so by age 16. Egg allergies were more persistent, with 4 percent outgrowing them by age 4, and 68 percent by age 16.

“We used to think that if you had failed to outgrow your allergies by a certain age, you wouldn't outgrow them at all,” says Robert Wood, MD, lead author of the study. “This study shows that there is reason to continue to test and be hopeful that allergies may still go away.”