Allergist and immunologist Dr. Gideon Lack's first hint that some peanut allergies could be prevented came more than 20 years ago, while he was giving a talk in Tel Aviv.
Lack, a professor of pediatric allergies at King's College London, asked an audience of about 200 Israeli allergists how many children with peanut allergies they had treated in the past year. When he asked that question during similar conversations in the United States and the United Kingdom, almost everyone in the room rose. To his surprise, only two or three Israeli doctors raised their hands.
He did some research and zeroed in on one key difference: Parents in the US and UK were told not to give their babies any peanut products until age 3 as a precaution against future peanut allergies. By contrast, puffy peanut snacks were a favorite staple of many Israeli babies' diets.
Lack and his colleagues decided to test the theory that early oral exposure could actually prevent children from developing peanut allergies. After following hundreds of children from infancy to early adolescence, they recently concluded that babies who eat this food early and often during their first five years of life are 71% less likely be allergic to peanuts at age 12.
The Learning Early About Peanut Allergy (LEAP) clinical trial finally overturned official guidance given to new parents and has potentially prevented countless new cases of a serious, life-threatening allergy.
“It was revolutionary,” said Dr. Rita Kachru, a UCLA allergist and immunologist. “It really changed the entire paradigm and understanding of food allergy.”
The team recently published the third and final report of their longitudinal study.
In it first phasewhose results were published in 2015The team recruited 640 babies between 4 and 11 months old considered at high risk of developing allergies, either because they were already allergic to eggs or had severe eczema.
Half of the babies were prohibited from consuming any peanut products during their first five years. The other half had to eat at least 6 grams of peanut protein per week.
After five years, 13.7% of the peanut-avoiding children who did not have a peanut sensitivity at the start of the trial had a peanut allergy at the end.
But only 1.9% of peanut eaters in this group did so: an 86% relative reduction in peanut allergy risk. For children who showed some initial sensitivity to peanuts at the start of the test, eating peanuts was associated with a 70 percent relative reduction in the development of a full allergy.
“The results have the potential to transform the way we approach food allergy prevention,” Dr. Anthony Fauci said at the time. Fauci was then director of the National Institute of Allergy and Infectious Diseases, which helped fund the study.
In it second stage, researchers asked 556 participants in the original study to avoid peanuts completely for a year, to see if continued exposure to peanuts was necessary to prevent allergy formation. Only a few children who had previously eaten peanuts without problems developed an allergy after not eating them for 12 months.
In the third phase, published last month in the New England Journal of Medicine, researchers evaluated 508 children who had participated in the first two studies.
The participants had been free to eat or avoid peanuts as they wanted for the six years since they were last studied. The team found that 15.4% of participants in the group who avoided peanuts in early childhood had peanut allergies by age 12, while only 4.4% of those who ate peanuts from an early age did.
“It was doubly gratifying because our hypothesis was correct, but more importantly we now have a strategy to prevent – and I would say, almost eradicate – the development of peanut allergy in the population,” Lack said over Zoom from London.
The incidence of food allergies began to increase markedly in the 1980s, particularly in Western industrialized nations. In 1997, 0.4% of People in the US had been diagnosed with peanut allergies. Today, about 1.8% do.
In the midst of the search for explanations, one from 1989 study found that babies whose exposure to common allergenic foods was severely restricted in their first two years of life ended up with fewer allergies than those in the control group.
Based largely on that research, in 1998 the United Kingdom instructed women not to eat peanuts during pregnancy or while breastfeeding if they or their partner had a family history of allergies, and to prevent their children from eating peanuts until the age of 3. . of Pediatrics adopted similar guidelines in 2000.
After the first two LEAP reports came out, both the American Academy of Pediatrics and the British Society of Allergy and Clinical Immunology issued new guidelines in 2017 incorporating the results. They now advise children at highest risk of developing a food allergy (those with eczema, egg allergy, or both) to start eating peanut products between 4 and 6 months. For children without risk factors, the AAP says, peanuts can be introduced whenever the baby starts eating solid foods.
“The guidance and recommendations prior to the LEAP study, where we were simply avoiding peanuts because we were afraid of peanut allergy, were completely discarded,” said Dr. Jenny Lee, an allergist and immunologist at UC Irvine. “It changed the way we practice.”
Nine years after the initial findings were published, there are signs that this approach is preventing new allergy diagnoses. In Australia, where guidelines now also encourage early consumption of peanuts, a large study published in 2022 found that 2.6% of 1-year-old children were allergic to peanuts in 2018-2019, compared to 3.1% in 2007-2011.
Despite strong evidence, the AAP's updated guidelines have not resulted in clear communications to all parents that early introduction of peanuts prevents allergies, said Dr. Katie Marks-Cogan, an allergist and immunologist who practices in Culver City.
Marks-Cogan says she asks parents of children with newly diagnosed food allergies if their pediatrician has talked to them about introducing allergenic foods early. Most of the time they say no.
“They'll still say… 'Aren't you supposed to wait up to a year for milk and three years for nuts and peanuts?' A lot of parents still think that, and it's because it's slow to change things in medicine,” Marks-Cogan said. “Early introduction is actually safer and better.”
Times Editor Karen Kaplan contributed to this. report.
