The LEAP Trial 12 Months Later: Are We Ready to LEAP-On Peanut Allergy?


Researchers announced results from the second phase of a landmark food allergy study, with the data showing that feeding peanuts to babies at high risk for developing the allergy sharply cuts their chance of becoming allergic by age 5.

Children in this second phase of the study avoided peanuts for 12 months. They were still not allergic to peanuts after avoiding peanuts for a year. 

The first study was called Learning Early About Peanut Allergy (LEAP)

LEAP is the first large study demonstrating the possibility of preventing food allergy through eating peanuts early, instead of delaying until a child is older.

Allergists from around the world are discussing the second phase, called LEAP-On, at the annual meeting of the American Academy of Asthma, Allergy & Immunology this weekend.

A review of the first LEAP study:

The first LEAP trial enrolled 640 infants, all between 4-11 months of age. They were randomly placed into two groups:

  • One group avoided any peanut until 5 years of age
  • The other group ate 2 grams of peanut 3 times a week until 5 years of age

All babies had moderate-to-severe eczema and/or egg allergy. Researchers gave them skin prick tests and an oral food challenge (OFC) to peanut at the start of the study.

The LEAP trial showed a significant reduction in peanut allergy at 5 years of age for infants who ate peanut, compared with those who avoided.

The results showed:

  • Children with a negative skin test at the start of the study had an 86% relative reduction of developing a peanut allergy
  • Babies with a skin test wheal of 1-4 mm had a 70% relative reduction

This was the first large scale study demonstrating the possibility of prevention of food allergy through early introduction.

What did researchers do in the second phase of LEAP?

The LEAP-On study used the same children from first phase. This time, researchers asked all children in both the avoidance and consumption groups to avoid eating peanuts for 12 months. 

Why? Researchers wanted to determine if allergy was truly prevented by eating it early, or if these infants were being desensitized. Becoming desensitized is a process similar to oral immunotherapy.

LEAP-On enrolled 88.5% of children from the original trial (556 children). Adherence to peanut avoidance in both groups was high during the 12 months families were told to stay away from peanuts:

  • 90.4% in the original peanut avoidance group, and
  • 69.3% in the peanut-eating group

What were the results for the two groups?

After 12 months of avoiding peanut, children who were previously eating peanut and then stopped had no significant increase in developing peanut allergy: 3.6% at 5 years old, compared with 4.8% at 6 years.

There were a total of 3 new cases of peanut allergy in both groups.

In addition, the original peanut-eating group continued to have much lower rates of allergy: 4.8% vs 18.6%.

What does this all mean?

According to the latest study data, early introduction of peanut to infants at high risk for developing a peanut allergy not only dramatically reduces rates of peanut allergy at 5 years of age, but this effect continues after one year of avoidance. This is likely due to true prevention, as opposed to a prolonged desensitization.

What are some remaining questions about the early introduction of peanuts to infants?

We still do not know how long babies have to eat peanuts, or how much to eat, in order to create what allergists call “sustained tolerance.” Children in LEAP ate 2 grams of peanut 3 times per week for 4 years.

Is it possible that eating peanut as much as one wants, without a schedule, or for a shorter amount of time will have the same effect? This remains unknown.

However, we have clear and strong evidence that the early and continued eating of peanut in high-risk infants is effective both in preventing the development of food allergy, and in continuing the effect.

What’s next?

The National Institute of Allergy and Infectious Disease, along with food allergy experts, is using the information to create new guidelines. The guidelines are open for public comment. A final version will help pediatricians and allergists encourage the introduction of peanut to all infants, with recommendations to first test and/or give an oral food challenge to babies at high risk. The guidelines are expected later this year.

It is important to stay up-to-date on news about food allergies. By joining our community and following our blog, you will receive timely news about research and treatments. Our community also provides an opportunity to connect with other patients who manage these conditions for peer support.




Du Toit, George, M.B., B.Ch., et al. (2016). “Effect of Avoidance on Peanut Allergy after Early Peanut Consumption.” The New England Journal of Medicine. Retrieved March 4, 2016.

Related articles:

New Guidelines: When to Feed Peanuts to Infants
New Peanut Allergy Study Does Not Say Parents Are to Blame
Landmark Study May Change How We Feed Peanut Butter to Infants


David R. Stukus, MD
Assistant Professor of Pediatrics, Section of Allergy/Immunology
Nationwide Children’s Hospital
Columbus, Ohio

Dr. Stukus joined the Asthma and Allergy Foundation of America (AAFA) Board of Directors in 2014 and serves as Secretary of the Board of Directors, as well as Chair of the Digital Strategy Committee. He currently serves as Chair for the Food Allergy and Anaphylaxis Subcommittee for the Medical Scientific Council for AAFA.

Dr. Stukus is originally from Pittsburgh, PA and received his undergraduate and medical degrees from the University of Pittsburgh. He completed his pediatric residency and Chief residency at Nationwide Children’s Hospital in Columbus, Ohio, followed by his fellowship in Allergy/Immunology at The Cleveland Clinic.

Nationally, he serves as Chair of the Quality Improvement Expert Panel for the American Academy of Pediatrics Chapter Champions Program on Asthma, Allergy and Anaphylaxis. He is an official spokesperson for the American College of Allergy Asthma and Immunology as well as Chair/Vice Chair and member of several ACAAI committees. He is active through the American Academy of Allergy Asthma and Immunology as well.

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Ok, I'm probably going crazy but these seem wrong too!

LEAP-On enrolled 88.5% of children from the original trial (556 children).
Adherence to peanut avoidance in both groups was high during the 12 months
families were told to stay away from peanuts:

- 4% in the original peanut avoidance group, and
- 3% in the peanut-eating group

On Fri, Mar 4, 2016 at 3:29 PM, Kids With Food Allergies <>
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