Mom watching young daughter eat bread and peanut butter

Food allergies are a fairly common concern for parents when their children are young. But how common are food allergies? Could your child have a food intolerance instead of a true food allergy? Will they outgrow their food allergy? Lena van der List and Dean Blumberg, pediatricians at UC Davis Children’s Hospital, answers these questions and more about food allergies in their podcast Kids Considered.

How common are food allergies?

True food allergy affects about 4-8% of children, and some grow out of it. As a result, food allergies affect about 2-5% of adults. There’s been a significant increase of food allergies in the last 10 years or so. There are a few theories for this rise, and it’s likely a combination of these theories that’s contributing to the rise in food allergies:

  • One is the hygiene hypothesis. This asserts that because the environment has become cleaner and we’re disinfecting things more regularly, kids’ immune systems aren’t as distracted by responding to frequent infections. Instead of responding to those infections, their bodies may respond by developing new allergies instead.
  • Another theory is that children are exposed to food proteins through the skin. Children can then become sensitized to that allergen, and it can cause a response later when they eat the food.
  • A third theory is attributed to pediatric guidelines from many years ago that advised children shouldn’t be introduced to historically allergenic foods at a young age. Not having these foods in kids’ diet early on may have contributed to the rise of allergies.

Food allergy vs. food intolerance

It’s estimated that about 35% of patients and/or parents report a food reactivity or intolerance which they believe is a true food allergy. The child may have nausea or diarrhea or another reaction that looks like it could be allergies, such as a rash around the mouth. If your child has experienced any of these reactions with no other symptoms, it may not be a true food allergy. You should discuss this with your child’s pediatrician.

True food allergy can be reproduced when eating a certain food. A child typically doesn’t have a reaction the first time they eat a food. Peanuts are an exception to this because, most likely, the child has already been sensitized through their skin or some other way.

What are the most common food allergies?

The most common foods that cause allergies are:

  • Milk
  • Egg
  • Peanuts
  • Tree nuts
  • Fish
  • Shellfish
  • Wheat
  • Soy

These 8 foods make up 90% of food allergies. But what about strawberries? Although this fruit is not listed as one of the most common food allergies, it seems like you or many people you know may say they’re allergic. It’s possible that this “allergy” may have had a mischaracterized or misdiagnosis because it looked like an allergy. As discussed above, it could show up as a rash, but there are no other symptoms. Therefore, it may just be a food intolerance.

How are food allergies diagnosed?

If you suspect your child has a food allergy, bring an ingredient list to your child’s pediatrician. You will likely also be asked about the food preparation process (such as scrambled egg vs. baking egg in a cake). Be prepared to detail how many times your child has eaten the food. Information about timing are the most important – from the time your child ingested the food until the reaction. True allergic reactions usually happen within minutes and rarely appear more than two hours after exposure. Your child’s pediatrician will also want to know more about your child’s medical history and family history.

From there, tests can confirm that it’s actually a food allergy. A blood test can look at the food of concern, and a skin prick test can determine if the food in question causes an immediate response. Blumberg and van der List do not recommend a panel test that includes the 20 most common food allergies. They advise that a test should look at the specific foods of concern, as opposed to a panel test which can result in a false positive.

What are the guidelines on feeding children peanuts at an early age?

In 2015, a study called LEAP (or Learning Early About Peanut allergy) looked at giving children peanut products at an early age. The study found that feeding children peanut products between age 4 and 11 months was beneficial. In patients who ingested peanut products three times per week, the number of peanut allergies decreased from 14% to 2% by age 5.

For parents with a child who has severe eczema or prior egg allergy, consult with your child's pediatrician and potentially have an allergy test done before introducing peanuts.

Can people outgrow food allergies?

About 80% of people will outgrow a milk, egg, wheat, or soy allergy. These are much more common in childhood. About 20% of people will outgrow a peanut, tree nut, fish, or shellfish allergy. However, this is not something you want to experiment with on your own. Talk to your allergist and they can track your allergy over time.

Listen to other Kids Considered podcasts by pediatricians Dean Blumberg and Lena van der List