Younger Siblings of Peanut-Consuming Children Experience Increased Risk of Peanut Allergy

The risk of peanut allergy was significantly reduced if the younger siblings were introduced to peanuts in their first year of life

MILWAUKEE, Feb. 26, 2026 /PRNewswire/ -- Younger siblings of children who eat peanuts have an increased risk of peanut sensitization and allergy, however, this sensitization can be mitigated by early peanut introduction, according to new research being presented at the 2026 AAAAI Annual Meeting.

"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," said lead author Michelle Huffaker, MD, FAAAAI, 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 (NCT00329784, NCT01366846, NCT03546413). An interactive model using multivariate generalized linear mixed models was developed to show the predictive probabilities for peanut sensitization and allergy in the younger siblings of LEAP participants, depending on whether their younger sibling consumed peanut in the first year of life, the duration of eczema and their household peanut consumption.

The younger siblings' peanut sensitization and allergy risk independently associated with increased family peanut consumption, especially by the LEAP participant and older siblings (p=0.0085 and p=0.0607, respectively), with a range effect OR for peanut sensitization 16.74 [(2.06, 134.66) p=0.0085] and range effect OR for peanut allergy 13.45 [(0.89, 203.96) p=0.0607]. The duration of participants' eczema was also independently associated with increased peanut sensitization and allergy risk (both p<0.001). Peanut sensitization and allergy risk were significantly mitigated if the younger sibling introduced peanut in the first year of life (p<0.001 and p=0.019, respectively), independent of eczema duration and household peanut exposure.

The research supports the Lack dual-allergen exposure hypothesis, which proposes that food sensitization occurs with environmental exposure, whereas tolerance occurs through oral consumption. By examining the interplay of environmental peanut, eczema and early peanut introduction on the development of peanut sensitization, this research shines an important light on factors that can mitigate allergy sensitization and improve outcomes for pediatric patients.

Visit aaaai.org to learn more about peanut allergy. Research presented at the 2026 AAAAI Annual Meeting, February 27 – March 2 in Philadelphia, PA, is published in an online supplement to The Journal of Allergy and Clinical Immunology (JACI).

The American Academy of Allergy, Asthma & Immunology (AAAAI) is the leading membership organization of more than 7,100 allergists, asthma specialists, clinical immunologists and other professionals with a special interest in the research and treatment of allergic and immunologic diseases. Established in 1943, the AAAAI is the go-to resource for patients living with allergies, asthma and immune deficiency disorders.

SOURCE American Academy of Allergy, Asthma & Immunology (AAAAI)