Considered "transitional" a generation ago, milk and
egg allergies now appear to be more
persistent and harder to outgrow, according to new research
from the Johns
Hopkins Children's Center.
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 appear in the
November and December issues of 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," said lead investigator Robert
Wood, professor and head of allergy and
immunology at Johns Hopkins Children's Center. "Not
only do more kids have allergies, but fewer of
them outgrow their allergies, and those who do, do so later
Researchers caution that their findings may reflect
the fact that relatively more severe cases
end up at Johns Hopkins Children's Center, but they believe
there is a trend toward more severe, more
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
said. "Why this is happening, we just don't know."
Earlier research suggested that three-quarters of
children with milk allergy outgrew their
condition by age 3, but the Johns Hopkins 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
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 Johns Hopkins team 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 anytime
soon. When counseling parents about their child's
prognosis, pediatricians should use antibody test
results, the researchers say.
One encouraging finding: Some children lost their
allergies during adolescence, which is later
than believed possible, suggesting that doctors should
continue to test patients well into early
adulthood to determine if they may have lost their
Milk and egg allergies are the two most common food
allergies in the United States, affecting 3
percent and 2 percent of children, respectively.
Co-investigators in the two studies are Justin
Skripak, Jessica Savage, Elizabeth Matsui and
Kim Mudd, all of Johns Hopkins Children's Center.
The studies were funded in part by the National
Institutes of Health and supported by the
Eudowood Foundation, the Food Allergy Initiative and Julie
and Neil Reinhard. Wood is a consultant
for Dey Pharmaceuticals and has received support from Merck