Younger siblings of children who eat peanuts have an increased risk of peanut sensitization and allergy, but this sensitization can be mitigated by early peanut introduction, according to new research presented at the Annual Meeting of the American Academy of Allergy, Asthma & Immunology (AAAAI), held in Philadelphia from February 27 to March 2, 2026.
“New data from the LEAP Siblings Study show that the younger siblings of LEAP participants were at increased risk of peanut sensitization and allergy if the younger sibling did not introduce peanut into their diet in the first year of life and had household members consuming peanut. This risk was even greater for the younger siblings with eczema. These findings support the concept that peanut allergy can develop with exposure to peanut through the skin, and that this risk can be overcome by introducing peanut into the diet at an early age,” commented lead author Michelle Huffaker, MD, on behalf of the Immune Tolerance Network and the LEAP Study Team.
For this study, researchers used data on younger siblings and their household peanut exposure from the Immune Tolerance Network LEAP Trials. The findings showed that peanut sensitization and allergy risk were significantly mitigated if the younger sibling introduced peanut in the first year of life. This research supports the dual-allergen exposure hypothesis, which proposes that food sensitization occurs with environmental exposure, whereas tolerance occurs through timely oral consumption.