Food Allergy Myths and Facts

From the WebMD Archives

You're done with your restaurant meal and it's time to the pay the bill. But before you even reach for your wallet, you get an itchy feeling down your back. Can't be food allergies, you think. Don't they go away when you become an adult?

There's a lot of confusion out there about eating and allergies. Learn how to separate truth from fiction so you can sit down to the dinner table with confidence.

Myth No. 1: Food allergy is the same as "intolerance" or "sensitivity."

There are similarities, for sure. Allergy, intolerance, and sensitivity are a little bit like siblings. They all belong to the same "family" of bad reactions to food. But there are big differences.

An allergy happens when the immune system, your body's defense against germs, has a reaction to a particular food. It can be mild, like an itchy feeling or hives. Sometimes you get severe symptoms -- called anaphylaxis -- like trouble breathing, a swollen tongue, or dizziness.
Food intolerance means your body is missing an enzyme you need to digest some type of food. If you're lactose intolerant, for instance, you don't have enough lactase, an enzyme that lets you digest dairy products. If you're gluten intolerant, you can't process gluten, which is found in some grains including wheat, barley, and rye.

What happens if you eat something you're "intolerant" to? You might get some of the same symptoms as a food allergy, but it can't trigger anaphylaxis. Over time, however, this reaction can damage the lining of your small intestine and can keep you from absorbing the nutrients you need from your food.
Food sensitivity is different. It is something of a catch-all category for an unpleasant, though not serious, reaction from a food. Think headaches from having too much chocolate or acid reflux triggered by spicy foods.

"Food sensitivities are certainly an inconvenience, and they make you feel lousy, but they're not life-threatening," says allergist Marc McMorris, MD, medical director of the University of Michigan Food Allergy Clinic.

What allergy, intolerance, and sensitivity do have in common is how you prevent them. Your best strategy: stay away! Avoid any food that's got the problem ingredient in it.

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Myth No. 2: Children never outgrow food allergies.

"Somewhere around 90% to 95% of kids outgrow dairy, egg, wheat, and soy allergies," McMorris says. That used to happen by the time they started school, but that's not necessarily the case anymore. Research suggests children now take longer to outgrow milk and egg allergies, though the majority are allergy-free by age 16.

The chances that your child will outgrow a shellfish, tree nut, or peanut allergy are much lower, a study suggests.

Myth No. 3: Most food allergies are caused by additives such as artificial colors and flavorings.

"Absolutely a myth," McMorris says. It's true that some reactions to additives are similar to those caused by food allergies. Nitrates, for instance, can cause hives and itching. And red and yellow food coloring have been linked to anaphylaxis.

The actual allergy triggers are the proteins in the food, McMorris says. Food additive intolerance is rare. Less than 1% of adults have it.

Myth No. 4: Most serious reactions from a food allergy are caused by peanuts.

Any food you're allergic to could cause a serious reaction, whether it's peanuts, tree nuts, milk, eggs, wheat, soy, fish, or shellfish. Those eight foods make up 90% of food allergies in the U.S. All of them have the potential to be life-threatening, McMorris says.

Myth No. 5: You only need a blood test to diagnose a food allergy.

Blood tests can sometimes be misleading. They may have a result called a "false positive." In other words, it says you're allergic when you're really not. How often does that happen? A whopping 50% to 75% of the time, McMorris says.

To get a clear diagnosis, an allergist may do something called a "food challenge." He'll give you small doses of a food and watch you to see if you get an allergic reaction. If there are no symptoms, he'll gradually increase the amount. Still no signs of trouble? You're declared allergy-free.

"Food challenges can confirm that somebody actually has a food allergy," McMorris says. "They're also used to see if someone has outgrown a food allergy."

WebMD Feature Reviewed by Melinda Ratini, DO, MS on February 1, 2016

Sources

SOURCES:

Food Allergy Research & Education.

Wayne Shreffler, MD, PhD, director, Food Allergy Center, MassGeneral Hospital for Children.

National Institute of Allergy and Infectious Diseases.

Marc McMorris, MD, medical director, University of Michigan Food Allergy Clinic.

American College of Allergy, Asthma & Immunology: "Food Additive Intolerance."

Gupta, R. Annals of Allergy, Asthma and Clinical Immunology, September 2013.

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