Children born outside the United States have significantly lower odds of developing allergic disorders, including asthma, eczema, hay fever, and food allergies, according to a recent study in JAMA Pediatrics.
The study also found kids born outside the U.S. who lived in the U.S. for longer than 10 years when compared with those who resided for only 0 to 2 years had significantly higher odds of developing any allergic disorders, including eczema and hay fever, but not asthma or food allergies.
For the study, researchers at St. Luke's-Roosevelt Hospital Center in New York City examined data from the National Survey of Children's Health, a group of more than 91,600 children between the ages of 0 and 16 who have been tracked since 2007-2008.
The researchers found 20.3 percent of children born outside the U.S. had one allergic disease, compared to 34.5 percent of those born in the States.
Over the last 30 years, factors such as climate change and the increase in global travel may have influenced the prevalence of allergies and asthma everywhere. There is a strong suspicion that where we live - including our geography, climate, lifestyles, and habits - may affect our propensity to develop allergies and asthma.
Having said that, there are some limits to the study. First of all, the data is self-reported and unconfirmed by clinical assessment – not the most reliable source of information. In addition, the way we assess and diagnose asthma in the U.S. is different than in China, which may lead to higher number of reported cases in the U.S. A study using the same definitions and diagnosis for each disorder would give us a better idea if American children have more allergies.
Is there anything we can do to prevent developing allergic disorders in the U.S.? Right now, it's a growing and developing area of research on how to prevent the onset of allergies. While there is some recent evidence that early exposure can help a baby develop tolerance, we do not know this for sure, and we do not know the window of opportunity, so to speak, for this to happen.
However, there are ways to minimize your symptoms if you or your children have allergies. Avoidance of potential triggers may be a possibility for some allergens, such as dust mite, cat, dog or other pets. Same with other indoor allergens such as cockroaches and mice, common in inner city dwellings.
Pollens are harder to avoid, and we generally don't like to tell people to restrict what they like to do, but keeping the windows closed and air conditioner on helps while people are indoors. With regard to eczema, there may be a relationship to food exposure, the most common being milk, soy, wheat and egg, but this really applies only to those with moderately severe eczema at a younger age.
Lastly, another thing that could be contributing to the development of allergies and asthma is our sedentary lifestyle. While there is no conclusive evidence for this, we do know that obesity is related to asthma, and perhaps symptoms of allergy, if not true allergy itself. Climate change may also be playing a role in the increase in allergies, so while it is not possible for one person to change "climate", we should perhaps be careful about our carbon footprint, even if it is for the benefit of future generations.