Food Allergy Fact and Fiction

New research suggests that certain foods are not as allergenic as you fear.
When to Worry: Food Allergies
When to Worry: Food Allergies

The Basics of Baby Food Allergies

My first baby, Nicholas, loved to eat. He filled up on breast milk until he topped 20 pounds at 6 months, then started fortified cereals like a pro. He loved vegetables, and his eyes lit up when I fed him yogurt.

Then one spring afternoon, after I'd scrambled an egg yolk for us to share, my smiling, healthy 9-month-old woke from his nap with a strangled cry. He had thrown up in his crib, and his tiny body was covered with angry, splotchy hives. I couldn't change his diapers fast enough to keep up with the diarrhea. While I held him, trying to remain calm so I could figure out why my baby was sick, it hit me -- the egg. That afternoon, we began our journey into the world of food allergies. As neither my husband nor I have food allergies, we had lots to learn.

"It's estimated that food allergies up to 8 percent of children," says Scott H. Sicherer, MD, of the Jaffe Food Allergy Institute at Mount Sinai School of Medicine, in New York City. While that means young food-allergy sufferers number in the millions, Dr. Sicherer stresses the importance of securing a trustworthy diagnosis before drawing any dietary conclusions.

Restricting a baby's diet without your pediatrician's guidance carries risks of its own. "The biggest danger is that you create a child who has a narrow range of food choices," says Frank Greer, MD, past chair of the American Academy of Pediatrics (AAP) committee on nutrition and professor of pediatrics at the University of Wisconsin Medical School, in Madison.

Eliminating a suspected food, which could be filled with important nutrients, from your child's diet before any allergy has been diagnosed is a misguided approach that can mask or trigger other health concerns, adds Amal H. Assa'ad, MD, a professor of pediatrics and director of Cincinnati Children's Hospital Medical Center's Food Allergy Clinic.

What Are Food Allergies and Where Do They Come From?

Just the Facts

An itchy rash. Diarrhea. Upset stomach. Is it a virus, a food allergy, or something else? Knowing the difference can help you and your baby rest, and eat, easier.

In a food allergy, the immune system reacts to a harmless food as if it were a threat and creates histamines and antibodies to fight it. Symptoms range from a tingling in the mouth and swelling of the tongue and throat to difficulty breathing, hives, vomiting, abdominal cramps, diarrhea, and a potentially fatal drop in blood pressure or shock, known as anaphylaxis. Every exposure may increase the reaction's severity. (Intolerances, also called sensitivities, may cause diarrhea, but they're not allergies; they occur when the body has trouble digesting a certain food.)

Ninety percent of all food-allergic reactions are to peanuts, eggs, milk, shellfish, wheat, soy, fish, and tree nuts (such as almonds and walnuts). Fewer than 10 percent of kids with food allergies react to corn, strawberries, and citrus fruit. Because babies don't typically eat a wide range of foods, the most common allergies seen early on are to milk, eggs, and soy, notes Dr. Sicherer.

As their immune systems mature, most children outgrow allergies to egg and milk by the time they enter elementary school. Food allergies can be triggered at any age, even after a food has been ingested for years, but allergies to peanuts and different types of fish are typically the most life-threatening and often manifest themselves early and last for life.

The Genetic Connection

As an infant, my eldest son struggled with bouts of blotchy eczema and asthma, conditions often shared by those with food allergies. "Eczema is one of the earliest markers of an allergic person," says Dr. Assa'ad. A family history of eczema, asthma, and allergies also raises the stakes. Seasonal and environmental allergies, like my hay fever and my husband's allergy to dust, directly increased our two sons' risk. And although both my boys faced and overcame an egg allergy early in their lives, their peanut allergy remains.

"You may inherit the susceptibility to become allergic. It's not anything that the mother does when she's pregnant or breastfeeding or anything that the father does," says Dr. Assa'ad. Some children just get a bigger share of the genes that predispose them to food allergies.

If your infant is diagnosed with asthma, eczema, or a food allergy, follow your doctor's instructions on the timing of solid foods, says Dr. Greer. If none of these conditions is present, then you don't have to wait to introduce any food once your infant begins solids between 4 and 6 months, he adds. (Of course, certain foods might also have to be restricted because of other health concerns or choking hazards.)

Smart Feeding Strategies

In late 2007, Dr. Greer and the AAP's committee on nutrition revised the AAP's nutritional guidelines for babies with eczema or a family history of allergies.

  • Try to exclusively breastfeed your baby for at least four months, and don't restrict your own diet.
  • Choose formulas carefully if you must supplement. Dr. Greer suggests that parents not use formulas made from more common allergy triggers like cow's milk or soy. Instead, use hydrolyzed protein formulas. They contain predigested proteins, making them easier to digest. They're less likely to cause allergic reactions, says Dr. Greer.
  • Using "hypoallergenic" formulas that are made with hydrolyzed proteins may delay an allergy's onset, but the formula won't prevent it from occurring.
  • If your baby has eczema, delay solid foods until she is about 4 to 6 months old. She will get the nutrients she needs from breast milk, with the possible exception of iron, which she can take as a supplement. Your doctor may also suggest restricting her diet, such as waiting to introduce eggs until she is 2 years old.

Tips on Testing

If you suspect your child has a food allergy, preparation and planning is key to diagnosis and management.

Keep a food diary. As with any baby, irrespective of allergies, introduce new foods one at a time, two to three days apart. Record everything that your baby eats for several weeks as well as any related symptoms (eczema, fussiness, gas).

Talk to your pediatrician and visit an allergist. Although it may be tempting, don't diagnose your child's allergy. Establish good relationships with doctors you trust who can advise you.

Get your child tested. Your doctor may recommend a radioallergosorbent test (RAST) or a prick-skin test. RAST, the latest version of which is ImmunoCAP, is a blood test that measures levels of antibodies to specific food proteins. High levels of antibodies indicate a possible allergy. It can take anywhere from a few days to a week to get results from this very sensitive test; 50 to 60 percent of positive RAST results are false positives. In prick-skin tests, results are nearly immediate: Any food that causes a raised bump or hive is positive. Fifty to 60 percent of positive skin test results are also false positives.

"Both of the tests measure the same things," explains Dr. Assa'ad. "It's not like one test is better than another," she adds. "Go into an allergist's office, you're going to get the skin test; go into a pediatrician's office, you're going to get the blood test."

If personal histories are uncertain and preliminary tests are inconclusive -- say your kid's prick-skin test registers a wheat allergy but her favorite snack is toast -- she may need the most accurate test available. A food challenge, which medical staff must closely monitor, requires that the patient ingest gradually increasing amounts of an allergen and wait for a reaction.

Learn more. Dr. Assa'ad, who tests babies as young as 3 months to see if they tend to be allergic, points out that any test is only valid for that individual at a particular point in time. A child who has eaten peanut butter and jelly for years, for example, could one day have an allergic reaction to her once-favorite meal. On the other hand, my sons, who used to have an extreme reaction to eggs, now enjoy baked goods and other foods containing cooked eggs. To get a good handle on the developing immune system, Dr. Assa'ad suggests retesting your child every one or two years to confirm the continued presence of food allergies, especially as diagnostic tools improve.

Living Healthy, Living Safe

You can help ease the stress of living with food allergies -- from daycares to family vacations -- by being prepared.

Read food labels carefully. A peanut-allergic child, for example, can't eat plain M&Ms safely because they are processed on the same machinery as peanut M&Ms. (Beware of sunflower seeds as well; the manufacturer that produces them may sell peanuts too.)

Ask about flu shots. While the mumps-measles-rubella vaccine is cultured with egg, studies have shown that it is safe for children with egg allergies. However, the flu shot, also cultured in egg, may cause a reaction in rare instances. Discuss with your allergist whether the benefits outweigh the risks.

Make a plan. Determine the steps you need to take in case your child has an allergic reaction. Communicate your plan and any emergency precautions to caregivers, family members, and teachers, as well as your child. For example, mine is simple: First, administer epinephrine, such as EpiPen Jr.; second, call 911; third, call the parents.

The first few minutes of a reaction are critical -- early treatment with epinephrine and/or a liquid antihistamine, such as Benadryl, saves lives. Because not every ambulance in every state carries epinephrine, it's best for both you and your caregiver or child's school to have a supply on hand.

Carry safe food and snacks with you at all times. Give them to daycare providers, babysitters, and friends who may watch your child.

With more research under way, potential for vaccines and other new food-allergy treatments keeps parents like me optimistic for the future. For now, my happy, healthy 10- and 8-year-old sons live normal lives -- few people ever notice the EpiPens they wear in a pack around their waists, the only clues of their life-threatening food allergies.

The Top 8 Hidden Food Dangers

Experts estimate that these foods cause 90 percent of food-allergy reactions.

Federal labeling laws require manufacturers to more clearly identify ingredients associated with the top eight food allergens. The Food Allergy and Anaphylaxis Network provides ingredient-reading cards that list unusual names and food sources for these allergens. Here's a sampling.

Allergen: Egg
Alternate Names: Albumin, lysozyme, globulin, ovumucin, vitellin, Simplesse™ (found in low-fat foods)
Food Sources: Egg substitutes, mayonnaise

Allergen: Milk
Alternate Names: Calcium, whey, lactose, casein
Food Sources: Cream, high-protein powder, sour cream, cottage cheese, cakes, puddings, hot chocolate, cheese, yogurt

Allergen: Fish or shellfish
Alternate Names: Agar, carrageenan
Food Sources: Worcestershire sauce, Caesar salad, dressing, cod liver oil

Allergen: Soy
Alternate Names: Guar gum, vegetable protein, lecithin, carob, starch, emulsifiers, flavorings, stabilizers
Food Sources: Vegetable broth or oil, tofu, soy sauce, tempeh, shortening, edamame, chorizo

Allergen: Wheat
Alternate Names: Gluten, semolina, modified food starch, MSG, vegetable gum
Food Sources: All-purpose flour, bleached flour, bran, American cheese, canned soup

Allergen: Peanuts
Alternate Names: Natural and artificial flavoring (read labels carefully to identify what kinds of artificial flavors might be in a food product)
Food Sources: Ice cream, chocolate, gravy, marzipan, egg rolls, candy, cookies

Allergen: Tree nuts
Alternate Names: Cashews, almonds, pecans, walnuts, Brazil nuts, hazelnuts (also called filberts), pine nuts, pistachios, macadamias, natural and artificial flavoring (read labels carefully to identify what kinds of artificial flavors might be in a food product)
Food Sources: Barbecue sauce, crackers, ice cream, foods with peanuts (may be cross-contaminated with tree nuts)

Elissa Sonnenberg is an editor at Cincinnati Magazine, in Ohio.

Originally published in American Baby magazine, October 2005. Updated May 2010.

All content here, including advice from doctors and other health professionals, should be considered as opinion only. Always seek the direct advice of your own doctor in connection with any questions or issues you may have regarding your own health or the health of others.

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