A seven-year-old girl in Virginia recently died from a severe allergic reaction to a peanut. The girl, Ammaria Johnson, ate a peanut given to her by a friend during recess. She immediately had trouble breathing, broke out in hives, and soon died. It’s not clear if Johnson or her family were aware of her allergy, but incidents like these remind us just how deadly food allergies can be.
When it comes to peanut allergy deaths, one of the most famous was that of a 15-year-old Canadian girl who died after a kiss in 2005. It caused a media sensation: the bizarre and tragic tale of young love cut short by a fatal kiss from a boyfriend who had accidentally doomed his girlfriend by eating a peanut butter snack a few hours earlier.
It was a cautionary tale that resonated with fearful parents around the world. However the peanut “kiss of death” report turned out to be a media-created legend, not a true story; a coroner concluded that the girl actually died from a severe asthma attack that had nothing to do with her peanut allergy.
Most cases of mistaken cause-and-effect confusion about food allergies aren’t this well-known, but research has shown that they are common. Far fewer people have allergies than widely believed — and, interestingly, than the sufferers themselves believe. If you ask people whether they have food allergies, around 12 percent will say yes.
However studies show most of those people are wrong. The New York Times writer Jane E. Brody, in a piece discussing a comprehensive new report from the National Institute of Allergy and Infectious Diseases, points out that “According to the panel’s detailed and well-documented report, about one child in 20 and one adult in 25 have a food allergy, nowhere near popular estimates that up to 30 percent of Americans are afflicted.”
On the surface, the idea that a person wouldn’t know whether her or she is actually allergic to a food seems to defy common sense: Either a person has a bad reaction to a particular food or she doesn’t, right? How could a person not know?
However in the real world of medicine and psychology it’s not so clear. Our minds create associations between causes and effects that do not necessarily exist. For example if a person becomes ill after eating a dish of shellfish and pasta, it’s very difficult to know what caused the problem: the wheat in the pasta, the shellfish, the milk in the cream sauce, or something else entirely.
Symptoms of food allergies are easily confused with other minor medical problems that may have nothing to do with food. Some people may experience nausea, rashes, hives, and other issues after eating foods, but that doesn’t mean the foods caused the problems. Some cases may even be food poisoning — the meat wasn’t fully cooked, or someone used cream that had been left out a little too long.
Another reason for the overdiagnosis of food allergies is that the two most common medical tests often produce false positives, indicating an allergy exists when it doesn’t. Often no test is done at all, and people (or parents) self-diagnose food allergies: Why go through the trouble and expense of a formal medical test when you can just make a mental note to avoid whatever foods you suspect caused the problem?
There is only one definitive way to be certain whether a patient is truly allergic to a specific substance, and it involves no fancy blood tests or skin pricks. In fact it’s very “old school”: a doctor isolates the suspect substances and the patient eats them under medical supervision to see if there’s any reaction.
The concern among some researchers about the overdiagnosis of allergies is that people (especially children) may be put on unnecessarily restrictive diets by well-meaning parents.