The number of children who have food allergies not only is increasing, it encompasses 4 percent of all kids in the United States, according to an analysis of four large, national surveys published Monday in the journal Pediatrics.
The study is the first to make a broad estimate about the prevalence of food allergies among U.S. children and supports previous studies suggesting that allergy rates are rising rapidly for reasons that are unclear.
Government researchers found that self-reported food allergies increased 18 percent from 1997 to 2007. Health care visits for food allergies in children nearly tripled between two periods studied: 1992 through 1997 and 2003 through 2006. In the latter period, U.S. children had an average of 317,000 visits to health care settings per year for food allergies.
The data suggest a real surge in illnesses and not just better awareness and diagnosis of the problem, said the lead author of the study, Amy Branum, a health statistician with the National Center for Health Statistics.
“To see almost a tripling of visits in a 13-year period is pretty good evidence that this isn’t just parents hearing about food allergies on the news and then thinking their children have it,” Branum said. “We used four different surveys, and to see an increase in food allergies in all of those surveys is very telling.”
Several theories have been proposed to explain why more children have food allergies, Branum said.
One prominent theory is the hygiene hypothesis, which is based on the notion that today’s children are less exposed to germs and other disease- causing substances than were previous generations — preventing their immune systems from developing normal responses to protect against invaders. The immune system then overreacts to relatively harmless substances, causing allergies, eczema or asthma.
Large, long-term studies are needed to determine who is most likely to develop allergies and why, Branum said. Food allergies are costly and inconvenient and can be life-threatening.
“Getting to the source of what is causing this trend is critical,” she said.
