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Allergy Testing in High Risk Infants, Should We Screen Before Introducing Highly Allergenic Foods?

With allergic infants being “frequent flyers” these days, it’s important to have the latest information at your fingertips.

This question came up during a webinar on Infant Food Allergy we did for the Primary Care Dietitians’ Association (PCDA) back in November 2021:

“Did I do the right thing?”

A Dietitian present explained she had recently seen a child who was high risk for peanut allergy and advised mom to go ahead and introduce peanut without having the child tested.

What do you think?


We’ll unpack what the science and national organizations have to say about allergy testing in high risk infants, but first, a bit of background information to bring you up to speed if you haven’t been following the allergy tidal wave in recent years.


In 2019, the Canadian Paediatric Society (CPS) and the American Academy of Pediatrics (AAP) came out with recommendations on early introduction of allergenic foods to help prevent the onset of developing allergies.


The science is quite clear on the benefits of introducing peanut and egg early.

The best time to introduce allergenic foods to prevent atopic disease in high risk infants is at around 6 months of age, but not before 4 months.


The now famous Identifying infants at high risk of peanut allergy: The Learning Early About Peanut Allergy (LEAP) screening study in 2013, recommended that those at highest risk should get screened, that is, undergo allergy testing, before we introduce peanuts.

But what happens in areas where access to specialists is limited? How does the science translate to actual practice?


First, we need to understand which child is at increased risk of developing a food allergy.


The high risk allergic infant is usually defined as having one of more of these:

Severe eczema that is refractory to treatment

Positive egg allergy

A first-degree relative with a food allergy or atopy


Is it safe for the high risk allergic infant to be exposed to highly allergenic foods?

Based on the evidence, children at high risk should be screened by an allergist before peanuts are offered.


Here is what the science has to say:

The LEAP study recommended to:

“strongly consider evaluation with peanut specific IgE and/or skin prick test and, if necessary, an oral food challenge. Based on test results, introduce peanut-containing foods. Earliest age of peanut introduction is indicated between 4 to 6 months. Those with mild to moderate eczema or no risk can go ahead and introduce peanut-containing foods around 6 months of age”.


Is this truly being done in practice? Do your clients have access to a quick referral for a pediatric allergist? Who will supervise the oral food challenge?


Here is how the science translates to practice:

US: National Institute of Allergy and Infectious Disease (NIAID)

Strongly suggests allergy testing specifically for peanuts prior to introducing this high allergenic food in high risk children.


Canada: Canadian Pediatric Society (CPS), Australia: Australasian Society of Clinical Immunology and Allergy (ASCIA) and UK: British Society of Allergy and Clinical Immunology (BSACI)

Routine screening of high risk infants is not recommended, in fact, it is discouraged.
Their explanation: false positive results can be confusing and limited access to allergy specialists and supervised food challenges delays the benefits of early introduction.


Bottom line:

All infants can be introduced allergenic foods early, especially peanuts and eggs

Introduction is most beneficial at around 6 months of age, but no earlier than 4 months

Allergy testing is not routinely recommended in Canada, Australia or the UK before introducing highly allergenic foods in the high risk infant

If you practice in the US, you may want to consider a referral to an allergist before introducing peanuts in a high risk infant

High risk infants are defined as having either: severe eczema, egg allergy and/or a first-degree relative with a food allergy or atopy


What do you do in your practice? We’d love to hear from you.



Charlene and Julie


P.S. Still have questions around introduction of highly allergenic foods? If you’re interested in learning more about infant food allergies and infant nutrition, join our wait list for our flagship course: Infant Nutrition Essentials.

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