A Parent’s Guide to the LEAP Study on Peanut Allergy Prevention

Thanks to the LEAP study, we know that introducing babies to peanut early and often significantly reduces their risk of developing a peanut allergy. But how was the LEAP study conducted, what exactly did the study reveal, and what do the findings mean for your family? In this article, we’ll break down everything parents need to know about the LEAP study.

The LEAP Study: Overview

  • The study focused on babies at high risk for peanut allergy. All of the children in the study had severe eczema, egg allergy, or both. Therefore, all participants were at high risk of developing a peanut allergy.
  • Initially 640 children in the United Kingdom, between 4-11 months of age, took part in the LEAP study.
  • The children were randomly divided into two equal groups, where they were directed to either consume peanut regularly or avoid peanut completely until age 5.
  • The children in the “consume” group ate at least 6 grams of peanut protein per week, divided into three or more doses per week, until they reached the age of 5. The peanut protein was provided in age appropriate form.

Learn more about the LEAP trial from this 1 minute video from the New England Journal of Medicine:


We’ve included a summary of the LEAP study below:

Questions Answers

What was the purpose of the LEAP study?

"evaluated strategies of peanut consumption and avoidance to determine which strategy is most effective in preventing the development of peanut allergy in infants at high risk for the allergy"

Who was the study’s lead investigator?

Dr. Gideon Lack (King’s College, London)

Who funded the LEAP study?

The study was supported by grants from organizations including:

  • The National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH)
  • FARE (Food Allergy Research and Education)
  • The National Peanut Board

No manufacturer of peanut products, including The National Peanut Board, could contribute to the study design, the analysis of data or the preparation of the results, so there was no conflict.


The LEAP study was peer-reviewed by impartial experts before it was published.

Who took part in the LEAP study?

  • All infants at high risk for peanut allergy – those with severe eczema, egg allergy or both
  • Initially 640 children participated
  • Starting between 4-11 months of age

What made them high risk for peanut allergy?

Severe eczema, egg allergy, or both

How was the LEAP study conducted?

Babies were first given a skin-prick test (SPT) to determine if they had an existing peanut allergy.

· Only babies with a negative SPT and babies with a positive SPT but very small wheals (1-4mm), moved forward into the study.


The children were randomly divided into 2 groups, with equal numbers of babies with positive SPT and negative SPT.

· One group consumed peanut regularly until the age of 5

· The other group avoided peanut completely until the age of 5

Were any babies excluded from the study?

Yes. Approximately 9% of infants who were pre-screened in the SPT were excluded from enrolling because they likely already had a peanut allergy. These babies had large wheals (raised red, itchy bumps) when they were exposed to peanut during an initial skin prick test.

How much peanut did the “consume” group eat? How often?

  • At least 6 grams of peanut protein per week, divided into 3+ doses per week
  • They followed this dosing until they reached the age of 5
  • The children were fed age appropriate peanut protein for safety reasons.

Did the study have any safety issues?

  • There were no significant differences in serious adverse events or rates of hospitalization between the avoidance group and the consumption group.

How did the researchers check to see if the children developed a peanut allergy?

Doctors assessed the children at three times:

  • At 12 months of age
  • At 30 months of age
  • At 5 years of age

Doctors also had between-visit consultations with parents and additional clinic visits were scheduled.


At 5 years of age, the children were tested to determine if they had a peanut allergy, by means of an oral food challenge.

What did the results how?

  • Early, sustained consumption of peanut products was associated with a substantial and significant decrease in the development of peanut allergy in high-risk infants.
  • The early introduction of peanuts significantly decreased the frequency of the development of peanut allergy among children at high risk for this allergy.
  • Early, consistent peanut introduction reduces peanut allergy risk by over 81%
  • Peanut avoidance was associated with a greater frequency of clinical peanut allergy than was peanut consumption.


Breaking Down the Findings

The LEAP study results show that introducing peanut to babies early and often helps prevent them from developing a peanut allergy. In the study, of those who avoided peanuts, 17.2% ended up developing a peanut allergy, compared to 3.2% for those who consistently ate peanuts. Comparing the two groups, those infants consuming peanuts were 82.35% more likely to not have a peanut allergy at 60 months of age.

What do the findings mean for you?

The LEAP study showed that early oral introduction of peanuts could prevent peanut allergy in infants with severe eczema, egg allergy or both. Sustained peanut consumption beginning in the first 11 months of life, as compared with peanut avoidance, resulted in a significantly smaller portion of children with peanut allergy at the age of 60 months. This intervention was safe, tolerated and highly efficacious.

Introducing peanut to babies as early as 4 months of age, and consistently feeding them peanut multiple times per week over several years, reduced their risk of peanut allergy by more than 81%.

The LEAP study shows that you shouldn’t delay the introduction of peanut to your baby and advice to delay the introduction of peanut for a child’s first few years of life (as was previously recommended by the AAP in 2000) is incorrect. Delaying peanut introduction results in a greater frequency of clinical peanut allergy than consuming peanuts.

Because of the LEAP study’s significant findings, landmark medical guidelines for introducing peanut were established including guidelines from the AAP.

Introduce Allergens Safely and Easily with Ready. Set. Food!

LEAP Trio Study - 2024 Update

The LEAP Trio Study continued to follow the kids from the original LEAP Study. In 2024, researchers concluded two important things: 

  1. Some kids stopped eating peanuts at age 5 for a year, while others continued. Even those who stopped were safe from developing a peanut allergy, proving the long-term benefits of early introduction.
  2. The most recent follow-up, published on May 28, 2024, shows that now, at 12 years old, those who ate peanuts as babies and toddlers still have lower rates of peanut allergies. This means early allergen introduction can prevent food allergies for life, giving kids a lifetime of food freedom.

About the author: Our Chief Allergist, Katie Marks-Cogan, M.D., is board certified in Allergy/Immunology and Internal Medicine, and treats both pediatric and adult patients. Originally from Cleveland, Ohio, she received her M.D. with honors from the University of Maryland School of Medicine. She then completed her residency in Internal Medicine at Northwestern and fellowship in Allergy/Immunology at the prestigious University of Pennsylvania and CHOP. After finishing training, she moved to Southern California and currently works in private practice. She is a member of the scientific advisory board for Ready. Set. Food! She currently resides in Los Angeles with her husband, 4-year-old son, and 1-year-old daughter where she enjoys hiking, building LEGO castles with her kids, and cooking with her family.

All health-related content on this website is for informational purposes only and does not create a doctor-patient relationship. Always seek the advice of your own pediatrician in connection with any questions regarding your baby’s health.

These statements have not been evaluated by the Food and Drug Administration. Products are not intended to diagnose, treat, cure or prevent any disease.  If your infant has severe eczema, check with your infant’s healthcare provider before feeding foods containing ground peanuts.