Food Allergies: One in Five People Think They Have One, but Only One in 10 Actually Do

One in five adults in the U.S. think they have a food allergy, but only one in 10 do, a study has revealed.

Of the total population, 26 million people have a food allergy, according to research published in the journal JAMA Network Open. But 19 percent believe they have the condition. Those people may instead have less severe intolerances, the authors wrote.

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To arrive at their findings, the researchers surveyed more than 40,400 U.S. adults.

The study also showed that half of adults with food allergies had been diagnosed by a doctor. Some 38 percent said they had visited an emergency room following a reaction to a food.

However, a quarter of those with food allergies were prescribed epinephrine, the potentially life-saving drug used to treat allergic reactions.

An allergy occurs when the body's immune system has an overzealous response to a trigger, such as food, pollen or insect stings. Depending on the severity of the allergy, it can rapidly trigger symptoms from the "merely bothersome to life-threatening," according to the Centers for Disease Control and Prevention. In some cases, an allergy can cause anaphylaxis, a severe reaction which can result in seizures and death if left untreated. Allergies to food, insect bites, latex and medicines can cause this response.

Dr. Ruchi Gupta, lead author of the study and professor of pediatrics at Northwestern University Feinberg School of Medicine, commented, "While we found that one in 10 adults have food allergy, nearly twice as many adults think that they are allergic to foods, while their symptoms may suggest food intolerance or other food related conditions."

"Food intolerance" is the term used to describe when an individual experiences symptoms such as stomach pain, bloating, rashes or itching after eating something their body finds hard to digest. Such symptoms generally strike several hours after the food is consumed. Unlike an allergy, an intolerance does not trigger an immune response, and the symptoms come on slowly.

Shellfish was found to be the most common food allergy, affecting 7.2 million adults. That was followed by milk at 4.7 million; peanut at 4.5 million; and tree nuts at 3 million. In fifth place was fin fish, which 2.2 million people are allergic to; while egg and wheat allergies both affect 2 million people, respectively; followed by soy at 1.5 million. Half a million people have an allergy to sesame, the study showed.

The research also revealed that for almost half of those with food allergies, their condition showed up in adulthood rather than childhood.

Gupta said the team was "surprised" by this and that further research was required to pinpoint why allergies develop later in life, and why certain food allergies—such as shellfish—appear to be so common.

Gupta stressed, "It is important to see a physician for appropriate testing and diagnosis before completely eliminating foods from the diet. If food allergy is confirmed, understanding the management is also critical, including recognizing symptoms of anaphylaxis and how and when to use epinephrine."

The study was published the week an 11-year-old boy with a fish allergy was suspected to have died after inhaling the smell of cooking cod.

Dr. Purvi Parikh, an expert in allergies and immunology at NYU Langone Health, told Newsweek on Thursday, "Never take your child's allergy lightly."

She urged sufferers to always carry an emergency epinephrine injector.

"Use it at start of symptoms, as this is the only medication that can save lives," she said. "Delay of this medication can be the difference between life or death."

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One in 10 adults in the U.S. have a food allergy, scientists believe. Getty Images