How Common Are Food Allergies?

Roughly 3.6 percent of Americans have at least one food allergy or intolerance, study says

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Food allergies and intolerances have been intensely investigated, debated, and carefully guarded against—but how many people actually deal with this health issue? As Roni Caryn Rabin reports for the New York Times, a new study has found that about 3.6 percent of Americans have adverse reactions to certain foods.

To reach this conclusion, researchers at the Brigham and Women’s Hospital (BWH) poured through the electronic health records of 2.7 million patients. Of these patients they identified 97,482 who had any type of negative reaction to food, including hives, vomiting, shortness of breath, wheezing, itching, and anaphylaxis. They published their results in The Journal of Allergy and Clinical Immunology

“Recent reports suggest that food allergies are on the rise, with more food-allergy related hospitalizations in the U.S. over the last decade,” said Li Zhou, an author of the study and researcher in the Division of General Medicine Primary Care at BWH, according to a press release. “However, many studies have been based on telephone surveys or have focused on a specific food allergen or allergen group. We recognized that the electronic health record system could offer a treasure trove of information about allergies to better understand which populations may be most affected and just how common food allergies and intolerances are in the U.S."

The results of this latest study suggest that less than four percent of people suffer from food allergies. This number is slightly lower than earlier estimates, which indicate that five percent of adults and eight percent of children have food allergies.

The analysis also revealed some trends in common allergies. Shellfish is the most frequently reported cause of allergic reactions, followed by fruits and vegetables, dairy, and then peanuts. The data also suggests that women and Asians are most susceptible to food allergies and intolerances.  

There are caveats to this latest study, as Amy Held points out for NPR. Food allergies are often self-diagnosed, and even medical professionals can find symptoms challenging to interpret. It can consequently “be difficult to determine what actually constitutes a food allergy and so pinning down how many people are afflicted can be tricky,” Held writes.

Follow-up is also a problem, as the WBH press release notes. There are currently less than 7,000 allergists and immunologists working in the United States, which may not be enough to effectively care for the number of people suffering from allergies. “[T]he U.S. doesn't have the capacity to evaluate/confirm allergies for all patients who initially test positive,” the press release states. Only one in five with a peanut allergy returned for follow up allergy testing, according to the release. 

And even with testing, recent research suggests that tree nut allergies are overdiagnosed. People who react to one type of nut may not be allergic to the rest—though the skin and blood tests may suggests otherwise.

More careful study is needed to understand the science of food allergies. Scientists' work investigating food allergies is definitely nut finished.