It happens at least once a week in my office. A parent or grandparent will ask "Why are there so many more children with peanut allergy these days?" This is typically followed by the statement, "When I was growing up, I didn't know anyone who had food allergies."
It is true – peanut and food allergies are on the rise. Most estimates are between 1 in 25 to 30 children in the United States that have a diagnosis of peanut allergy. That's roughly one child with peanut allergy in every classroom in America, in every grade level.
There is no consensus as to why this is the case, but there are several theories. Part of the rise in diagnosis comes from increased awareness from families and physicians, as well as more easily accessible testing, either through skin prick testing at an allergist's office, or blood testing that can be ordered by any physician. Another theory is called the "Hygiene Hypothesis", which basically states that as our society has shifted from living on farms into cities, we have less exposure to microorganisms. Our immune systems no longer have to practice fighting off infections, and instead turns its attention to harmless proteins/allergens.
Another thought concerns the production of peanuts for mass consumption. In the United States, peanuts are mostly dry roasted and perhaps this process alters the protein and increases its allergenicity. Lastly, it is possible that prior recommendations to avoid peanuts and tree nuts until 3 years of age did more harm than good. There is ongoing research that suggests earlier introduction may promote tolerance, whereas we used to think avoidance prevented allergy.
Bottom line, the rise in food allergies, and allergies in general, can be attributed to several different phenomena and there does not appear to be one clear link. Thus far, there is no effective way to prevent the onset of allergy as one's DNA, or genetic makeup, is the most important part of the equation. Some of us are just programmed to be allergic, starting in the womb. And to complicate matters more, there is likely a complex interaction between genes and environment which may result in a variety of different outcomes, depending upon early life exposures, which are currently not well understood.
Believe it or not, but this blog was the short answer to this question. I am hopeful that we'll have more concrete answers someday soon, which may help provide clues towards a cure. But for now, those with food allergies can only treat their condition with strict avoidance and vigilance for hidden sources of exposure. However, I can provide at least one piece of sound advice to the families I care for: There is nothing that you could have done to prevent this from happening.
For more information on Nationwide Children's Hospital's allergy and asthma services, click here.
David Stukus, MD, is an associate professor of pediatrics in the Section of Allergy and Immunology at Nationwide Children’s Hospital. Dr. Dave, as his patients call him, is passionate about increasing awareness for allergies and asthma.
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