A recent study found that while food allergies beginning in adulthood are common, those who self-diagnose often confuse food allergies with food intolerance.

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Can you tell the difference between a food allergy and food intolerance? Getty Images

Did you know that 10.8 percent of adults surveyed — more than 26 million people — in the United States report having a food allergy of some kind?

However, 19 percent of adults who think they have an allergy really don’t.

These findings are part of a new study published in JAMA Network Open that aimed to gauge how prevalent food allergies in the United States are today.

The researchers surveyed 40,443 adults online and by phone for almost a year, from October 2015 to September 2016.

Of the people who had at least one adult-onset food allergy, 38 percent reported having at least one food allergy-related emergency department visit over the course of their lifetime.

“A lot surprised me about the findings of our survey,” said lead author Dr. Ruchi S. Gupta, MPH, a professor of pediatrics and medicine at Northwestern Medicine. “The prevalence of 1 in 10 really having a convincing food allergy is a lot. That in itself was a bit of a surprise, even though it did support some of the past research that had been done.”

Gupta told Healthline that many people mistakenly brush aside food allergies as a feature of childhood, possibly discounting or ignoring what could be a serious health concern.

For those who reported an official diagnosis, an allergy to shellfish was the most common at 2.9 percent. Milk, peanut, tree nut, and fin fish came next. About 51.1 percent reported having experienced a severe reaction, while 45.3 percent said they were allergic to multiple foods.

Dr. Alice Hoyt, an allergist and immunologist at Cleveland Clinic, told Healthline that this is the “multi-billion dollar question.”

She highlighted several possible theories that currently exist, such as the “hygiene hypothesis,” which suggests that as societies become more hygienic they have less exposure to microbial organisms — germs.

“So, perhaps exposure to some low levels of germs actually helps our immune systems develop in a way that is less prone to allergy,” she said. “However, we know that too many germs or bad germs can cause severe illness, so hygiene is certainly an important medical advancement.”

Another possibility Hoyt points out is the relatively modern and oft-debated reality of highly processed foods that have become such a regular part of the American diet from the mid-20th century to now.

“Another consideration is food processing and that newer processes change foods in ways that are new to the human body,” she said. “One example is that roasting peanuts makes them more allergenic, so perhaps we should consider how our changes in food processing may impact the ways our immune systems and digestive systems interact with altered foods.”

She added, “Another consideration is the effect of increased use and amounts of detergents on our skin — the skin is the largest immune organ — as the skin plays a role in food allergy, too. Overall, as more researchers study food allergy and intolerance, we will get closer to answering this important question.”

Gupta echoed those thoughts, saying that researchers are always wrestling with what exactly has been changing in our environments and in our genetics to enable for the greater presence of food allergies.

One curious finding of the study was the 19 percent of people who mistakenly assume they have an allergy without actually ever receiving a concrete medical diagnosis.

Hoyt said that the term “food allergy” seems to mean different things to different people.

However, for an allergist, it means that a patient is at risk for anaphylaxis, a severe allergic reaction that could include serious symptoms like trouble breathing, hives, swelling, and even death.

For the lay person, she said that the term could just mean you got a headache from eating a certain food or you are experiencing some kind of uncomfortable digestive reflux.

“However, those symptoms are not consistent with food allergy and are more consistent with a form of food intolerance,” she said.

Food intolerances
aren’t life-threatening, and are when your body has difficulty processing certain foods.

Think lactose intolerance, which results from the body’s inability to digest lactose, the carbohydrate found in dairy. While this can lead to bloating, cramps, or diarrhea, this is different from a full-on milk allergy, which would result in more serious reactions.

Gupta said that a big part of this confusion and misinformation exists due to the fact that many people go to “Doctor Google first” rather than consulting a medical professional.

While it might seem more convenient to look for information online, Gupta stresses the importance of seeing an allergist or physician, who can give you a full diagnosis through accurate testing.

“It’s important for them to get a proper diagnosis so that they can be prepared. Go see a doctor, get properly diagnosed, and have a management plan,” she said.

Hoyt added that you should not be making serious diet changes without consulting your allergist or dietician first.

Judith L. Dodd, MS, RDN, LDN, FAND, an assistant professor at the School of Health and Rehabilitation Sciences at the University of Pittsburgh, says that she has seen a concerning shift of self-diagnosis by many patients throughout her career as a dietitian.

Dodd, who is also affiliated with the International Food Information Council Foundation, said that it can be frustrating to see people adjust their diets without getting the appropriate information from a professional.

“One of my major concerns is people will diagnose themselves [online] or diagnose themselves because of a friend or family member rather than have a team of experts assess for them whether it is an allergy or not,” Dodd told Healthline. “One example is the ‘gluten free’ fad, which is a joke. You have a lot of the people out there avoiding foods without getting diagnosed by a team, without a registered dietitian.”

She added, “If you had an actual allergy or something like celiac disease, you would need to know how the food is prepared, where it comes from. You would need a plan from a doctor who is trained in food sensitivities to look at the whole picture.”

Hoyt said that if you are concerned you are having an adverse reaction to a certain kind of food, it’s crucial you speak to an allergist rather than ask Dr. Google for a diagnosis.

“If a person thinks they have an adverse reaction to a food, they should begin avoiding it and talk with their physician about that for further recommendations such as diet modifications,” she said. “Allergists are able to tease out allergies from intolerances and provide appropriate therapies that, ultimately, may be life-saving. With more therapies becoming available, it is important that allergy patients see their allergist at least annually so they can have the most up-to-date treatment plans.”

Dodd added that it’s important people look at the credentials of the expert to make sure they’re seeking out the best treatment and advice possible.

For her part, Gupta said that this study has opened up “101 questions” and countless avenues she would like to travel down for her research.

She is interested in adult-onset allergies and the factors that could lead to someone developing an allergy outside of childhood.

“It’s so fascinating that shellfish allergy is so high in adults. What is going on with shellfish that so many adults develop allergies to it? I’m hoping this will also promote more research into adult food allergies because most of us have been focused on kids and food allergies,” she said. “Now that we know what a problem it is in adults, I’m hoping more will happen in terms of looking at the causes.”

A study published in JAMA Network Open found that more than 10 percent of American adults have an officially diagnosed food allergy. Beyond this, 19 percent falsely think they have an allergy when they don’t.

Researchers say there is a lot of disinformation about food allergies and intolerances spread throughout social media. They suggest you ignore the noise and consult a medical team — think allergists and dietitians — who can help you monitor what you eat and come up with a proper diet and treatment plan.