Children Born or Raised in the US Have Higer Risk of Developing Allergies, Eczema

Children born in the United States have a higher risk of developing skin, food allergies and asthma compared to children born in other countries, according to new research published Monday.

Researchers found that just over 20 percent of children born outside the U.S. had any type of allergic disease, while 35 percent of children born within the country developed some form of allergy.  The link held true regardless of participants' ethnicity, income level or whether they lived in an urban or rural area. Children born outside the United States were 73 percent less likely to have asthma, 55 percent less likely to have eczema and 66 percent less likely to have hay fever.

The study, published in the journal JAMA Pediatrics, did not offer a strong explanation for why that is, only suggested it's a concoction of several environmental factors, including an over-emphasis on hygiene that isn't exposing kids to allergens, along with an unhealthy diet.

Meanwhile, children who immigrated to the United States were about 44 percent less likely to have an allergy condition compared with children born in the country. However, the buffer against allergies seen in the study wore off after the child lived over 10 years in the U.S.  Children who were born in the United States but whose parents were immigrants also had a reduced risk of allergies.

"This is definitely something we see clinically and we're trying to better understand, what is it in our environment that's increasing the risk of allergic disease?" Dr. Ruchi Gupta, who studies allergies at the Northwestern University Feinberg School of Medicine in Chicago, told Reuters. Gupta was not involved in the new study.

"The findings of the present study are consistent with the broader hygiene hypothesis, which suggests that either infections or certain microbial exposures in early childhood may confer protection against [allergies and asthma]," said study researcher Dr. Jonathan Silverberg, a dermatologist at St. Luke's-Roosevelt Hospital Center in New York City.

Without exposure to germs, the immune system has shifted away from fighting infection to developing more allergic tendencies. More than half of Americans ages 6 to 59 years are sensitive to at least one allergen, according to a national survey conducted from 1988 to 1994 by the National Institutes of Health. That's two to five times higher than rates found in a previous 1976 to 1980 survey.

The study was based on information from about 91,800 U.S. children whose parents participated in a between 2007 and 2008. The current number of allergy cases could be higher, researchers noted. 

In an attempt to counter escalating allergy rates in 2008, the American Academy of Pediatrics backtracked on previous recommendations issued in 2000 which urged parents not to give milk until age 1, eggs until 2 and peanuts, shellfish, tree nuts and fish until 3. Now the American Academy of Allergy, Asthma & Immunology released a report in March 2013 which said highly allergenic foods can be introduced to babies between 4 and 6 months and may even play a role in preventing food allergies from developing.