A new study suggests that up to 1 in 10 inner-city children is allergic to peanut, milk or egg.
“We expected a relatively high rate since this was a “high risk” birth cohort, with at least one parent with a history of allergy or asthma,” Dr. Robert Wood, study author and chief of pediatric allergy and immunology at Johns Hopkins, told Allergic Living. “However, even given that, the rate was far greater than predicted, especially since we just looked at three foods and required very strict criteria to diagnose food allergy.”
Researchers set out to determine what early-life factors influenced the risk of food allergies in inner-city children. They followed 516 children from Baltimore, Boston, New York and St. Louis for their first five years of life. Household exposures, levels of IgE (the allergy antibodies), and the history of allergic reactions were taken. The data showed that 9.9 percent of the children were allergic to one or more of peanut, milk and egg, a prevalence significantly higher than the self-reported food allergy rate of 6.5 percent.
More than half of the children studied were considered to be sensitized to a food allergen, which means blood tests in this larger group revealed IgE to specific allergens. Of this group, 9.9 percent were considered truly allergic, 17 percent were categorized as “possibly allergic”, and 28.5 percent were considered “sensitive but tolerant,” which meant they showed IgE for an allergen, but they had a history of eating the food without reacting.
If the study’s definition of allergy had been looser (i.e. based on IgE test results only), the rate of allergy would have been much higher.
Children with food allergy tended to be male, have been breastfed, and have less exposure to endotoxin (a form of bacteria). They also tended to have wheezing, eczema or sensitization to aeroallergens, such as pollen or dust mite droppings.
The study drew on data from The Urban Environment and Childhood Asthma birth cohort study, which since 2004 has followed children at risk for allergies who also live in inner-city areas where at least 20 percent of the population lives below the poverty line.
“Our findings are a wake-up call, signaling an urgent need to unravel the causes, contributors and mechanisms that drive the high prevalence of food allergies among an already vulnerable group,” said Wood in a Johns Hopkins press release.