Milk, Egg Allergies Now Tougher for Kids to Outgrow
When we were kids, milk and egg allergies were something a child generally outgrew. But just one generation later, these allergies now appear to be more persistent and harder to outgrow, according to new research from the Johns Hopkins Children's Center in Baltimore, Maryland.
In what are believed to be the largest studies to date of children with milk and egg allergies, researchers followed more than 800 patients with milk allergy and nearly 900 with egg allergy over 13 years, finding that, contrary to popular belief, most of these allergies persist well into the school years and beyond. Reports on the two studies appeared recently in the Journal of Allergy and Clinical Immunology.
"The bad news is that the prognosis for a child with a milk or egg allergy appears to be worse than it was 20 years ago," says lead investigator Robert Wood, M.D., head of Allergy & Immunology at Hopkins Children's. "Not only do more kids have allergies, but fewer of them outgrow their allergies, and those who do, do so later than before."
Researchers caution that their findings may reflect the fact that relatively more severe cases end up at Hopkins Children's, but they believe there is a trend toward more severe, more persistent allergies.
The findings also give credence to what pediatricians have suspected for some time: More recently diagnosed food allergies, for still-unknown reasons, behave more unpredictably and more aggressively than cases diagnosed in the past. "We may be dealing with a different kind of disease process than we did 20 years ago," Wood says. "Why this is happening, we just don't know."
Earlier research suggested that 75 percent of children with milk allergy outgrew their condition by age 3, but the Hopkins Children's team found that just one-fifth of children in their studies outgrew their allergy by age 4 and only 42 percent outgrew it by age 8. By age 16, 79 percent were allergy-free.
Similar trends were seen in the egg-allergy group. Only 4 percent outgrew this allergy by age 4, 37 percent by age 10 and 68 percent by age 16.
The researchers found that a child's blood levels of milk and egg antibodies — the immune chemicals produced in response to allergens — were a reliable predictor of disease behavior. The higher the level of antibodies, the less likely it was that a child would outgrow the allergy any time soon. Pediatricians should use antibody test results when counseling parents about their child's prognosis, they note.
One encouraging finding: Some children outgrew their allergies during adolescence, which is later than believed possible, suggesting that doctors should continue to test patients well into early adulthood to check if they may have outgrown their allergies.