In 2010, a study published in the Journal of Allergy and Clinical Immunology found that, of 5,300 households surveyed in 2008, 1.4 percent had children thought to have peanut allergies. That's more than three times the number from a similar survey in 1997 (0.4 percent), the study's authors said.
Total nut allergies in 2008 were measured at 2.1 percent of children and 1.3 percent of adults, showing that while adult tree nut allergies have remained relatively constant, the rate of allergies in children has been multiplying.
Since the release of that information in 2010, many scientists have stepped forward with theories as to why it is that these numbers are so shockingly high. A threefold increase in just 10 years is astonishing, to say the least. Of the theories given, three have gained enough support among researchers to be considered plausible.
Theory 1: The rise is actually just better awareness
This theory basically postulates that the reason the sharp rise in children's peanut allergies is in such contrast to the relatively steady number of adults with the allergy is because we have become more aware of peanut allergies in the past couple of decades.
Because doctors and people at large are generally more aware of the allergies, the actual allergy is more likely to be diagnosed when symptoms occur. Because the 2010 study didn't measure the severity of the allergies in survey respondents, it may be that many of the more mild cases of allergic reaction that are now more likely to be diagnosed are the reason the numbers seem so high.
Similar things have happened to other medical conditions after increased awareness made them more easily diagnosed. Breast cancer, for example, and many mental illnesses have seen higher diagnosis numbers in large part because of increased public awareness of those maladies.
Theory 2: Genetic modification of peanuts causes allergic reactions in more people
This theory has not yet been tested, though many are working on doing so. The basis is the fact that in the United Kingdom in 1999, when genetically modified peanuts were introduced to the country, peanut allergies among kids jumped by 50 percent. This correlation could be causal or just a coincidence.
Because genetically modified peanuts were also introduced in the United States at about that time, it would explain the jump in allergies here as well. Only rigorous study would find out for sure.
Theory 3: We're too clean
Usually referred to as the "hygiene theory," this is a common theory among those who study allergies in general. Allergies are believed to be more common now than they have ever been, though it's only been relatively recently that we've understood how allergies work. Still, the idea is that because we're in such clean environments and have so many ways of stopping disease before it starts, our body's immune systems are "bored."
These under-worked immune systems can sometimes decide to put their energy into non-threatening things instead, such as an allergy to peanuts. It's an idea that has gained some traction in the research community but has not yet been proven.
Which Is It?
It could be any of these theories or even another one that has yet to be proposed or gain attention. The truth is, no one knows why some people are allergic to peanuts while most are not. We may never know.