Nearly two decades ago, Dr. Gideon Lack, professor of pediatric allergy at King’s College London, and his colleagues asked: Would giving infants peanuts protect them from developing peanut allergies? At the time, nothing could have been further from U.S. standard practice, which cocooned babies from allergens until they were toddlers. But, horrifyingly, in what’s known as the LEAP study, the team discovered in 2015 that this avoidance might have been causing the epidemic of peanut allergy that had engulfed children in the U.S. and elsewhere—children given peanuts in the first months of life were around seven times less likely to develop an allergy to it. Recommendations were revised in 2017, and in October 2025 a paper in Pediatrics revealed that the alteration led to a 43% drop in peanut allergy incidence in the years following. In the period covered by the study, “about 200,000 cases of peanut allergy [were] prevented in the U.S. alone,” says Lack.
