Kids living in urban areas have a much higher prevalence of food allergies than those living in rural areas, reveals study.
In particular, kids in big cities are more than twice as likely to have peanut and shellfish allergies compared to rural communities.
"We have found for the first time that higher population density corresponds with a greater likelihood of food allergies in children," said lead author Ruchi Gupta, M.D., an assistant professor of pediatrics at Northwestern University Feinberg School of Medicine and a physician at the Ann and Robert H. Lurie Children's Hospital of Chicago (formerly Children's Memorial).
"This shows that environment has an impact on developing food allergies. Similar trends have been seen for related conditions like asthma. The big question is - what in the environment is triggering them? A better understanding of environmental factors will help us with prevention efforts," she noted.
Gupta, also a researcher at the Institute for Healthcare Studies at the Feinberg School, said some of her future research will focus on trying to identify the environmental causes.
The study included 38,465 children, 18 years and under, who comprised a representative sample of U.S. households. Their food allergies were mapped by ZIP code.
It found that in urban centers, 9.8 percent of children have food allergies, compared to 6.2 percent in rural communities, almost a 3.5 percent difference.
Peanut allergies are twice as prevalent in urban centers as in rural communities, with 2.8 percent of children having the allergy in urban centers compared to 1.3 percent in rural communities.
Shellfish allergies are more than double the prevalence in urban versus rural areas; 2.4 percent of children have shellfish allergies in urban centers compared to 0.8 percent in rural communities.
Food allergies are equally severe regardless of where a child lives, the study found. Nearly 40 percent of food-allergic children in the study had already experienced a severe, life-threatening reaction to food.
The states with the highest overall prevalence of food allergies are Nevada, Florida, Georgia, Alaska, New Jersey, Delaware, Maryland and the District of Columbia.
The study controlled for household income, race, ethnicity, gender and age. It tracked food allergy prevalence in urban centers, metropolitan cities, urban outskirts, suburban areas, small towns and rural areas.
The study will be published in the July issue of Clinical Pediatrics.