One of the great medical mysteries of the 20th century is to explain why children are suffering from more allergic diseases, at least in America. Asthma, hay fever, eczema, as well as peanut allergy are becoming very common conditions among children in the US. It is estimated that 10% of American children now have asthma, and 20% suffer with eczema. Once uncommon conditions are becoming the norm for our children. What is going on?
A new study, published in the Journal of the American Medical Association (JAMA), helps us get a little closer to understanding the explosion of allergy in America. The authors collected data on 92,000 American children who were born outside the U.S. and compared them with children born and living in the U.S.. The conclusion was startling: American children, born and living outside the United States, were much less likely to suffer from allergic disease than their peers born and living in the States. Furthermore, the researchers found that foreign-born American children who came to the U.S. to live showed a consistent rise in allergic disease after just a decade of living in America. Said another way, something about living in America seemed to promote allergic disease in a dose-dependent manner: the longer a child lived in the U.S., the more likely they developed allergy!
The results of this new study add additional information to a growing body of research that indicates that something about life in a Western country promotes allergy in children. But why? What is the environmental factor that triggers the aberrant allergic response in children? Some believe it is our reliance in the U.S. on processed food that often contains genetically modified grains, preservatives, and artificial flavors and colors. Other researchers think the big factor is pollution and unnatural chemicals in our environment. Others believe that the obesity epidemic is to blame. Currently, the leading theory is what researchers call the “hygiene hypothesis” is to blame. This theory points to the lack of microbial diversity that children are exposed to when they are infants, therefore permanently changing these infant’s immune response to common allergens like peanut protein and house dust.
Researchers are getting closer to answering the great allergy mystery, hopefully soon. Life for children with asthma, severe eczema, and food allergy can be miserable. Hopefully, we can not only explain these diseases but also, more importantly, prevent them. Being born and raised in America should be an incredible blessing, not a ticket to allergic disease.
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- Prevalence of Allergic Disease in Foreign-Born American Children
Jonathan I. Silverberg, MD, PhD, MPH; Eric L. Simpson, MD, MCR; Helen G. Durkin, PhD; Rauno Joks, MD
JAMA Pediatr. 2013;167(6):554-560. doi:10.1001/jamapediatrics.2013.1319.
Written by Paul Smolen M.D.