A Closer Look – When the Science Changes: The Peanut Allergy Story
Science is a process used to develop knowledge about the world. Over time, consensus develops around a scientific topic, such as a medical recommendation. However, science is ever evolving, incorporating new observations and questions. One example of this evolution of knowledge is the approach to preventing peanut allergies in children.
Starting in the 1990s with rising rates of allergies, physicians began to recommend that parents avoid giving infants peanuts, hypothesizing that this would help prevent development of peanut allergies. This recommendation was based on the best available information at the time — which in reality wasn’t that much. As more information became available, scientists and medical professionals started to question the recommendation, sparking a well-controlled and large research study. The result? A reversal in the recommendation. Let’s take a closer look.
In the late 2000s, Dr. Gideon Lack and his colleagues in the United Kingdom noticed that rates of peanut allergies in babies were much higher in the UK than in Israel. They noted that, in Israel, babies were regularly introduced to peanut-containing foods in the first year of life, whereas in the UK, these foods were avoided during the same life stage. These observations prompted the Learning Early About Peanut (LEAP) study. The LEAP study, published in 2015, indicated that giving peanuts to babies on a regular schedule early in their lives markedly reduced their risk of developing a peanut allergy. The data propelled a reversal in recommendations both in the UK and in the U.S., with the medical community pivoting to advise introducing peanuts to babies early in their lives.
In October of 2025, scientists from Children’s Hospital of Philadelphia’s Division of Allergy and Immunology published a study in the journal Pediatrics showing a decline in the prevalence of peanut allergy diagnoses in children in the decade since the LEAP study recommendations took effect. Find out more about what CHOP researchers Drs. Stanislaw Gabryszewski and David Hill found in the article, “Children’s Hospital of Philadelphia Researchers Observe Significant Reduction in Diagnosis of Food Allergies Following Expert Guidelines Encouraging Early Peanut Exposure.”
The LEAP study offers an example of the evolving nature of knowledge, the importance of observation and the desire to keep questioning, learning and refining knowledge.
Related resources
“Rethinking Peanut Allergies: The Science Behind Early Introduction” (Article, Unbiased Science)
“Everybody Was Wrong About Peanut Allergies. And That’s Okay.” (Article, MissTrust)
“Advice to feed babies peanuts early and often helped thousands of kids avoid allergies” (Article, PBS)