- Published on Wednesday, 26 February 2014 00:03
- Written by Grace Peace Yu, M.D.
Approximately 5.9 million children in the United States have food allergies, according to Food Allergy Research & Education (FARE).
This translates into one out of 13 children, or nearly two students in every classroom. With studies and the media reporting increases in children’s food allergies, many parents are understandably worried. The body’s immune system is an amazing thing when it works correctly, fighting bacteria and viruses. Food allergies occur when the immune system attacks a food protein because it mistakes it as a threat. When antibodies are released into the body to attack the allergens, it causes an allergic reaction. While we don’t completely understand why food allergies develop, we know there’s a genetic component. In identical twins, if one is allergic to peanuts, the other twin has a 67 percent chance of being allergic. In siblings, if one is allergic to peanuts, the other has a 7 percent risk of being peanut-allergic.
Any food can be the culprit, but peanuts, tree nuts, milk, eggs, wheat, soy, fish and shellfish trigger more than 90 percent of food allergies. Children of parents with allergies (such as hay fever) and those with eczema are at higher risk for food allergies. To help prevent an allergic reaction in these children, we recommend allergy testing before introducing any of these highly allergenic foods into their diet.
Food allergy symptoms may include one or more of the following.
• Hives • Runny nose
• Redness of the skin • Nasal congestion
• Itchy mouth or ears • Sneezing
• Nausea • Coughing
• Vomiting • Difficulty breathing
• Diarrhea • Wheezing
• Stomachache • Throat swelling
• Itchy nose • Faintness and/or dizziness
• Red, itchy or watery eyes • Hoarseness
Symptoms typically occur within minutes up to an hour after the food is ingested. According to FARE, a young child might describe these symptoms in the following ways.
• "This food is too spicy."
• "My tongue is hot (or burning)."
• "It feels like something’s poking my tongue."
• "My tongue (or mouth) is tingling (or burning)."
• "My tongue (or mouth) itches."
• "My tongue feels like there’s hair on it."
• "My mouth feels funny."
• "There’s a frog in my throat."
• "There’s something stuck in my throat."
• "My tongue feels full (or heavy)."
• "My lips feel tight."
• "It feels like there are bugs in my ears."
• "My throat feels thick."
• "It feels like a bump is on the back of my tongue (throat)."
Parents of children with food allergies worry about anaphylaxis - a severe and potentially fatal allergic reaction that inhibits breathing. Anaphylaxis is a medical emergency and should always be treated immediately.
The first line of defense is avoiding the food allergen. For example, if your child has a peanut allergy, you should help him or her avoid foods with even traces of peanuts. Avoid all foods with the labels "May contain peanuts," "Processed in a facility with peanuts" or "Manufactured on shared equipment with peanuts." Because the law doesn’t specify which type of label should be used, companies don’t indicate the level of risk to your child. Food from Thai, Vietnamese and Chinese restaurants, and from ice cream shops, often contains peanuts and is high risk for children with peanut allergies.
One recent study showed that each year, there is a 50 percent chance your child will accidentally ingest food that causes an allergic reaction. This is because it’s not always easy to know if a packaged food or restaurant meal contains a food allergen. It’s very important to be prepared for an unexpected allergic reaction.
Your child should always have access to an epinephrine auto-injector such as Auvi-Q, which provides audio instructions when opened. It comes in a twin pack, which is important because many allergic reactions require a second dose.
Your child should also have access to an antihistamine, such as liquid cetirizine or diphenhydramine.
To date, there’s no known cure for food allergies. A study in The New England Journal of Medicine found that patients allergic to eggs could be desensitized to eggs by giving small doses daily and gradually increasing the dose over time.
Recent studies have shown other food allergens, including milk, peanuts and tree nuts may react the same. This indicates that there may be a way to desensitize children who have food allergies.
While this is a breakthrough for those living with food allergies, the results are not ready for general public use. Doctors don’t recommend that people try to re-create the results at home because of the risk of causing a life-threatening allergic reaction.
Some parents ask me if their child will outgrow a food allergy. That depends on the food and the individual child. It’s likely a child will outgrow an egg, milk, soy or wheat allergy. If your child has a peanut allergy, there’s a 20 percent chance of outgrowing it. Children with tree-nut allergies have an estimated 10 percent chance of outgrowing it. Fish and shellfish allergies tend to be lifelong. I recommend an annual appointment with an allergist for testing and follow-up.
While exciting medical research is ongoing in food allergies, the best current defense is to help children avoid food allergens, quickly recognize the symptoms in the case of an accidental ingestion and immediately treat allergic reactions.
Dr. Grace Peace Yu is a board-certified allergist and immunologist at the Dublin and Fremont centers of the Palo Alto Medical Foundation.
The Palo Alto Medical Foundation and column editor Arian Dasmalchi provide the House Calls column. ■