A new study of adult food allergy prevalence in the United States offers some startling insights into what’s going on with Americans’ immune systems — and what they think is going on with their immune systems.
It found that 1 in 10 adults, or more than 26 million people, have a food allergy of some kind.
At the same time, 1 in 5 believe they have a food allergy but haven’t necessarily experienced the symptoms one would expect from someone with a true allergy.
Which means both that food allergies are extremely common — and that millions of Americans who think they’ve got one are probably wrong.
Researchers from Northwestern University surveyed more than 40,000 adults between the fall of 2015 and the fall of 2016, asking them whether they had a food allergy of some kind.
They also asked questions about what kind of reactions they’d experienced that led them to believe they were allergic to a food or foods.
The researchers then came up with a list of reactions they believe to be indicative of a true allergic reaction — things like hives, throat tightening, wheezing and vomiting. They did not include on that list symptoms like nausea or general gastrointestinal malaise, which are typically indicative of a food intolerance.
As awareness of food intolerance increases (products aimed at people with food intolerances now represent a $13 billion-plus industry), people are likely confusing signs of intolerance with allergies. And that probably accounts for the marked difference between the number of survey participants who said they had a food allergy and those who the researchers said fit the bill. A person who indicated he was allergic to, say, milk but had never experienced any of the specific reactions on the researchers’ list (like wheezing, vomiting, or anaphylaxis) would not have made the cut.
Which is not necessarily to suggest that millions of Americans are making up their discomfort.
It does, however, point to the importance of continued education on the difference between food allergies (which are an immune system response to a particular ingredient) and food intolerances (which happen when a person’s digestive system is irritated by a food or foods).
“Symptoms that patients experience are often misinterpreted,” Dr. Aikaterini Anagnostou, director of the food immunotherapy program at Texas Children’s Hospital, told HuffPost in an e-mail. (Anagnostou was not involved in the study.)
“Self-diagnosis of a food allergy is not a good idea and it is imperative to visit a specialist if there are concerns about allergic reactions,” she added. “A false diagnosis can result in excluding foods from the diet unnecessarily, whereas on the other hand, ignoring symptoms of a food allergy can put patients at risk of severe reactions on exposure to trigger foods.”
Food intolerances might be a genuine bummer, but they won’t kill you. Food allergies can.
The researchers found the most common food allergies were shellfish, milk, and peanuts.
A little more than half of the survey respondents developed their allergies in childhood, while the rest developed them as adults.
At this point, it’s not clear what, if anything, could help prevent adults from developing food allergies, although research is increasingly clear that introducing young kids to allergenic foods can help stave off more serious problems later on — and that is a big shift from what was recommended just a decade or two ago.
For example, the American Academy of Pediatrics says there is now strong evidence for giving babies peanuts early on, as early as 4 months for babies who have severe eczema or who have shown symptoms of an egg allergy. That’s a reversal of earlier AAP statements, which discouraged parents from giving babies who had risk factors for developing a subsequent allergy any peanuts before age 3.
Food allergies are on the rise, Anagnostou said, stressing that it’s important to follow guidelines for introducing new foods to infants to prevent allergies from developing — and to see your doctor if allergy symptoms crop up later in life.
This article originally appeared on HuffPost.