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Figuring Out Food Allergies

How to tell when it’s the real thing, and why seasonal sufferers should avoid certain foods

By Alexa Stanard

Spring allergy season is upon us, but airborne allergens aren’t the only culprits when you wheeze and itch. Food allergies are on the rise in the United States, and their symptoms can range from annoying to life-threatening.

Before you can protect yourself, however, it’s important to understand just what a food allergy is. An allergic reaction occurs when proteins in a certain food trigger the body’s formation of an antibody called immunoglobulin E or IgE.

“More commonly, people who think they have an allergy actually have an adverse reaction, which is not the same. The antibodies must be present,” says Christian Nageotte, M.D., associate program director for allergy and immunology fellowship at Henry Ford Health System. “People with lactose intolerance, for example, lack the antibody [IgE].”

Many times people confuse intolerance to a certain food with an actual allergic reaction; only about 2% of adults have true food allergies, Nageotte says. And did you know that an allergy to something in the air might mean there are foods that you should avoid? Our experts help sort out what you need to know about food allergies.

Is it really an allergy?

Allergies to foods, especially peanuts, have been on the rise for decades; in fact, the rate of peanut allergies in children has grown tenfold since the early 1990s, says Harvey Leo, M.D., a pediatric allergist with Allergy & Immunology Associates of Ann Arbor. The frequency of allergies to egg, milk, soy and sesame also is increasing.

The reason for the increase isn’t clear, though in the case of peanuts it might be linked to the American taste for the dryroasted version, according to Nageotte. Asian countries, which typically boil peanuts, have seen no such rise despite similar consumption rates.

But even an allergy-free childhood doesn’t guarantee an easy-breathing adulthood.

“Any allergy can occur at any age in life,” Nageotte says. “Nobody knows why that occurs, why someone can tolerate peanuts for 50 or 60 years then eat a peanut butter sandwich and have a reaction. That’s an unanswered question.”

The good news is, food allergies tend to decline with age as food tolerance builds and the intestine adapts to the allergen, says Cristina Cotronei-Cascardo, M.D., an allergist and internist with DMC Children’s Hospital of Michigan.

In the case of a food allergy, Nageotte says, you’ll need epinephrine, an injectable prescription medication.

A severe allergic reaction might cause a drop in blood pressure resulting in dizziness or lightheadedness, and difficulty breathing. If you’re experiencing such symptoms, head to the emergency room, Nageotte says. Allergic reactions can be fatal.;

The cross-allergy factor

The body often responds to proteins in certain foods in the same way it responds to airborne allergens. Someone whose hands get itchy from latex gloves, for example, might experience an itchy mouth or swelling of the lips after eating avocado, bananas or water chestnuts. All are derived from tropical plants (latex comes from the rubber tree), and Nageotte says they might share a common ancestor, which could account for similarities between them.

The part of the protein to which an individual becomes allergic might seem, to the immune system, similar to proteins found in other plant species, Nageotte says. So those allergic to the ragweed family might have problems with melon. If you can’t get near a beech tree, you might need to avoid cherries, apples and peaches. And an allergy to mugwort, a non-native invasive plant, could mean a similar response to celery.

The good news is you don’t need to give up your favorite fruit or veggie. That’s because it’s the fresh allergen that causes the reaction, says Leo.

“Active allergens [in produce] get broken down when you cook them,” he says. “If you’re allergic to apples, you eat apple pie or applesauce, and you’re fine.”

Nageotte notes that this applies to oral allergy syndrome, where the individual’s reaction is limited to the mouth. In cases where reactions extend beyond the mouth, such as a capsicum (pepper) allergy, food preparation will make no difference.

The majority of airborne-allergy sufferers won’t experience cross allergies, Nageotte says. “It’s just one of those phenomena we see frequently enough that we realize there’s an issue,” he says. “But having one doesn’t condemn you to having the other.”

EXPECTING A BABY? READ ON ABOUT ALLERGIES

There’s no clear gender difference when it comes to who gets allergies, experts say, but they can worsen for women who are pregnant.

“What happens is your immune system has to do something pretty amazing to carry a baby,” says Harvey Leo, M.D., a pediatric allergist with Allergy & Immunology Associates of Ann Arbor. “Allergies are an overreaction, or a mistake, of the immune system. A woman’s immune system has to selectively shut down during pregnancy. For women whose allergies manifest when [they’re] having children, they probably were always there and are resurging.”

For more information on allergies, visit the Web site of the American Academy of Allergy, Asthma & Immunology at www.aaaai.org.