A Dietitian’s Guide to Kid’s Food Allergies

Food allergies in children can be a daunting and overwhelming topic for parents. In this blog post, we will be reviewing the most frequently asked questions about kid’s food allergies, including what to look out for, how to identify potential allergens, and how to manage food allergies in children.

To give some background, here is the current state of food allergies in children (1,2):

• 1 in 13 children have food allergies
• If one food allergy is identified in your child, there is a 40% chance they have other food allergies as well
• From 1999 to 2011, food allergies have increased by 50%

So with the number of cases rising, let’s review the most common questions regarding food allergies in children:

What are food allergies? How are they different from food intolerances or sensitivities?

Food allergies are defined as an adverse health effect from an immune response to a specific food that occurs reproducibly on exposure to a given food (3). The key word here is reproducible. They occur with every instance of interacting with a certain food. However, some allergies are serving size-dependent or exercise-induced, which makes it challenging to identify allergies.

Food intolerances are a non-immune related response to a food that is normally tolerated at a lower dose.

Food sensitivities do not have a clear definition and include any symptom perceived to be related to food ingestion.

The main difference between these three terms is whether or not they act on the immune system or the GI tract. Also, this affects how each of them are diagnosed – more on that later!

What foods are considered “allergen foods”?

The eight foods that most commonly result in an allergic reaction are called the “Top 8 Allergens”. In fact, they are responsible for 90% of all food allergies in children (3).

In order of most common to least common:

• Shellfish
• Milk
• Peanut
• Tree nut
• Egg
• Fish
• Wheat
• Soy

For kids less than three years old, the most common food allergies are milk, eggs, peanut, soy, and wheat.

What symptoms should I look for to spot an allergy?

There are several categories of reactions kids can have to allergies. These occur immediately after food ingestion or several hours after ingestion (3).

Gastro-intestinal Symptoms

• Vomiting
• Abdominal pain
• Diarrhea
• Swelling Tongue
• Itchy Mouth
• Swelling of the lips or tongue

Dermatologic Symptoms

• Skin flushing
• Itchy skin
• Red skin rash
• Welts on the skin or raised hives

Respiratory Symptoms

• Anaphylaxis
• Dry Cough
• Sneezing
• Hoarse Throat

Cardiovascular Symptoms

• Dizziness
• Fainting

How are food allergies diagnosed? 

Food allergies are diagnosed with one or more of the following tests (3):

1. Detailed Food History. A medical history and physical exam are necessary to determine potential trigger foods for an allergic reaction. This also determines if the allergy is serving size-dependent or exercise-induced.

2. Skin Prick Testing (SPT). This test exposes your child to small amounts of allergens in the controlled environment of a medical clinic. Each small prick shows the reaction response of up to 50 allergens. However, just because there is a skin response during testing, it doesn’t always mean there is a clinically diagnosed allergy.

• SPT has a positive predictive accuracy of <50%, meaning if a response is measured during the test, there is less than 50% chance that it is a true allergy
• SPT has a negative predictive value of >95%, meaning that if there is no response measured, there is a 95% chance that there is no allergy

3. Oral Food Challenges (the gold standard!). Exactly what it sounds like – intentionally introducing a suspected allergen and watching for a reaction. This is the clearest way to establish an allergy but should be done in a hospital or clinic, especially if an allergy is suspected.

On a side note – food sensitivities also have blood tests available for diagnosis. However, they are incredibly under-researched and do not produce accurate results. The best way to assess for food sensitivity is an elimination diet of suspected food sensitivities one at a time.

When should I introduce allergen foods?

Allergens should be introduced within the first 6-12 months of a child’s life. The goal is to introduce allergen foods as early as possible.

If your child has eczema or another known food allergy, be careful about introducing allergens. Severe eczema and present food allergies increase the risk of being allergic to foods (4),

In terms of how allergens should be introduced, I’m leaving it to the feeding specialists! Linking a great guide here for introducing allergens within the first 100 days of a child’s life. This guides you through gradually increasing the serving size of allergen foods and how to do this one at a time. Check it out!

Does the early introduction of allergen foods help prevent allergies?

This is not a myth! Early introduction (around 6 months of age) to allergen foods reduces the risk of developing an allergy. However, most of the research we have on this is only for specific foods – peanuts, eggs, and milk (5).

• Introducing peanuts at 6 months old can decrease the likelihood of an allergy by 80%
• Introducing eggs within the first year of life leads to a 30% decrease in known allergy
• Introduction to cow’s milk within the first three months of life significantly decreases chances of an allergy within 3-5-year-olds

The thought behind early exposure is “training” the immune system to recognize allergens while it’s still developing. If allergen foods are not introduced, there is a higher chance the immune system will detect it as “foreign”.

Can kids outgrow their allergies?

Again, this is only relevant for certain allergen foods. 40-60% of children will outgrow milk, egg, wheat, and soy allergies (1). However, the age at which kids outgrow allergies is less defined. Although most data predicts outgrowth by age 6, some experience reactions until their teenage years.

There is little research about outgrowing allergies to peanuts, tree nuts, and shellfish.