Millions of Americans may be mistaken about their food allergy, new research suggests. It turned out that while almost 20% of people said they had food allergy, only half of the people reported the type of symptoms you expect from a person with an allergy.
Researchers interviewed more than 40,000 adults over the phone and internet between October 2015 and September 2016. Volunteers were asked if they had any food allergies and what symptoms they usually had. They were also asked if they had already been formally tested and diagnosed with food allergy by a physician.
In all, 19 percent of the national representative group reported having a food allergy, with the main culprits being mollusks, milk and nuts. But only 10.8 percent said they had symptoms consistent with an allergic reaction to food, such as hives, swelling of the lips or throat, and chest pain. Those who have not reported symptoms such as stomach cramps, stuffy nose or nausea.
The findings, published on Friday in the JAMA Open Network, roughly correspond to estimates from other studies, including those that confirmed a person's food allergy with medical tests or records. In terms of the US population, there are about 26 million American adults with food allergies – and there are probably almost as many Americans who mistakenly say they have one. But that does not mean that large numbers of people are pretending to have food allergies; it's just that we can get a bit confused about the terminology.
True allergies, as they are known, happen when the immune system reacts very quickly and specifically to a foreign substance harmless to us, whether food or a garment. Antibodies usually responsible for an allergic reaction are called immunoglobulin E or IgE. When doctors test allergies, they are IgE antibodies that they are looking for. But people may react badly to food for other reasons outside of this process.
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Lactose intolerance is probably the best-known example, and it happens because many adults are less able to break down lactose, the sugar commonly found in dairy products, into simpler sugars. Another genetic condition, celiac disease, makes people unable to digest gluten. Some people also appear to have delayed immune responses to non-IgE foods in the photo, although we are less sure about how often this happens and how to accurately diagnose. Many doctors, for example, criticize tests that promise to find such so-called food sensitivities with ease.
It is likely, then, researchers say, that people may be mixing an intolerance or food sensitivity to a food allergy.
What is also worrying is that many people with possible food allergies have apparently never talked to a doctor about it. Only half of the group said they had an official diagnosis from a doctor. And while many of us develop food allergies from early childhood, almost half reported having discovered about their allergy when adults.
This lack of diagnosis is worrisome, because food allergies are not something you want to stay in the dark. While your typical outbreak of lactose intolerance may make you very familiar with the bathroom, a food allergy can trigger a serious, life-threatening anaphylactic shock. In the study sample, 38 percent of people with food allergies said they had to go to the ER at least once in their lifetime, while about a quarter had a current prescription for epinephrine, which could prevent anaphylaxis.
Some of the people who have discovered their allergy in adulthood may have been fortunate enough to avoid offensive food for most of their childhood or have forgotten an earlier reaction but it is likely that many other people have developed their allergy later in life . Why this is happening is a crucial mystery that needs to be resolved.
"We were surprised to find that food allergies in adults were so common," said lead author Ruchi Gupta, a public health researcher and professor of pediatrics at Northwestern University's Feinberg School of Medicine in Chicago, said in a statement. "More research is needed to understand why this is occurring and how we can avoid it."
Overall, added Gupta, anyone who thinks they are not able to handle a particular food for any reason should ask their doctor to get to the bottom of it and not self-diagnose.
"It's important to see a doctor for proper tests and diagnostics before completely eliminating food from the diet," Gupta said. "If food allergy is confirmed, understanding the treatment is also critical, including recognizing symptoms of anaphylaxis and how and when to use epinephrine."