Providing lasting protection from peanut allergy

The study found that peanut allergy can be prevented into adolescence by introducing peanut-containing foods early in life. LightField Studios / Shutterstock

Peanut allergy is one of the most common food allergies. Food allergies occur when the body’s immune system reacts to a component of a food. This can lead to symptoms ranging from mild, such as lip swelling and hives, to a life-threatening reaction called anaphylaxis.

Peanut allergy usually starts in early childhood and often lasts for the rest of the person’s life. Researchers have made progress using a strategy called oral immunotherapy to treat peanut allergy. This involves feeding progressively larger doses of peanut over time, under medical supervision, to build immune tolerance. But it doesn’t work for everyone and can cause allergic reactions. And it would be better to prevent peanut allergy from developing in the first place.

Almost two decades ago, an NIH-funded study called Learning Early About Peanut Allergy (LEAP) began testing whether introducing peanut products early in life could reduce kids’ risk of developing peanut allergy. During the study, half of the 640 participants regularly consumed peanut products from infancy until age 5 years. The other half avoided peanuts.

The study found that early introduction of peanut products reduced the risk of peanut allergy at age 5 by 81%. In a follow-up study, called LEAP-On, children from LEAP were asked to avoid eating peanut products from ages 5 to 6 years. Even after this year of avoidance, most children from the original peanut-consumption group remained protected from peanut allergy at age 6.

The effects of oral immunotherapy for peanut allergy can wane over time. Therefore, researchers were concerned that the protective effects of early exposure to peanuts might also fade. To address this concern, the LEAP researchers designed a longer-term follow-up study, called LEAP-Trio, to measure peanut allergy into adolescence.

LEAP-Trio, led by Dr. Gideon Lack from King’s College London, followed 508 of the original study participants to an average age of 13. Since LEAP-On, those who were not allergic to peanuts had eaten or avoided peanut products as desired. The LEAP-Trio results were published on May 28, 2024, in NEJM Evidence.

During this extended time period, only one participant in the original peanut consumption group developed a new peanut allergy. Overall, only 4.4% of kids who were exposed early to peanuts had a measurable allergy to peanuts in adolescence. In contrast, 15.4% of kids in the early peanut avoidance group had developed peanut allergy. These results show that regular, early peanut consumption reduced the risk of peanut allergy in adolescence by 71% compared to peanut avoidance.

“Today’s findings should reinforce parents’ and caregivers’ confidence that feeding their young children peanut products beginning in infancy according to established guidelines can provide lasting protection from peanut allergy,” says Dr. Jeanne Marrazzo, director of NIH’s National Institute of Allergy and Infectious Diseases. “If widely implemented, this safe, simple strategy could prevent tens of thousands of cases of peanut allergy in the United States each year.”

Parents of infants who are at high risk for peanut allergy should talk with their health care provider before introducing peanut-containing foods. An allergy test may be needed to make sure the infant hasn’t already developed an allergy to peanut.