Groundbreaking research has revealed that early introduction of peanuts to infants, contrary to previous avoidance advice, can dramatically reduce the incidence of peanut allergies, with recent data showing a significant drop in cases among young children.
The story begins with Dr. Gideon Lack, an allergist, who noticed a stark contrast in peanut allergy rates between children in the United Kingdom and Israel. While practicing in London, he observed high rates of peanut allergy, but during a lecture in Tel Aviv, he was surprised to find that very few doctors reported cases, leading him to investigate the dietary habits in Israel. This observation sparked a decade-long investigation into why peanut allergies were virtually nonexistent in Israel compared to the UK.
In Israel, parents commonly give babies peanut-based snacks like Bamba from as early as 4 to 6 months of age. Lack hypothesized that this early exposure might be protective against developing allergies. To test this, he and his colleagues conducted a study comparing Jewish children in Israel and the UK, controlling for genetic factors, and found that peanut allergy was ten times more common in the UK, where peanuts were avoided in infancy. The median peanut consumption in Israeli babies was about 2 grams per week, while UK babies consumed zero, highlighting a clear dietary difference.
This observational study, published in 2008, suggested an association, but to prove causation, Lack’s team conducted the LEAP trial, a randomized controlled study funded by the NIH. They enrolled 640 infants at high risk for allergies and assigned them to either consume peanut products early or avoid them until age 5. The results, published in 2015, showed an over 80% reduction in peanut allergy in the early introduction group, with only 1.9% developing allergies compared to 13.7% in the avoidance group.
Historically, medical guidelines, including those from the American Academy of Pediatrics in 2000, recommended avoiding potential allergens like peanuts until later childhood to prevent allergies. However, this advice was based on limited evidence and was later withdrawn after new research emerged. Lack himself followed this advice with his own children, emphasizing how medical knowledge evolves through the scientific method and that what seems intuitive can be incorrect.
Following the LEAP study, guidelines were updated to recommend early introduction of peanuts for high-risk infants. A recent study published in Pediatrics found that since these changes, peanut allergy rates among US children under 3 have declined by 33% after the 2015 update and 43% after the 2017 update, potentially preventing nearly 40,000 cases. This decline has shifted peanut allergy from the most prevalent to the second-most common food allergy in young children, behind egg allergy.
The ongoing research includes the SEAL study, which investigates whether early treatment of eczema can prevent food allergies, based on the dual-exposure hypothesis. This hypothesis suggests that exposure to food proteins through the gut promotes tolerance, while exposure through inflamed skin can sensitize the immune system. Lack and his team are testing if moisturizers and topical steroids in early infancy can reduce allergy risks, building on the lessons learned from peanut allergy research.
The story of peanut allergies underscores that medical science is not static but evolves through observation, hypothesis testing, and correction. It serves as a powerful reminder of the importance of rigorous research and the scientific method in improving public health and challenging long-held beliefs.