Children’s risk of developing food allergies shifts as they grow older, a new study finds. The analysis of blood samples from 500 mother-child pairs revealed that sensitivity to various food allergens changes significantly between ages one and five. Researchers found that while peanut allergies often appear early, sensitization to other nuts and substances tends to develop later in childhood.
Shifts in Allergen Sensitivity
By the time a child reaches age five, the likelihood of having a food sensitivity rises from 25 percent to 40 percent. The specific foods triggering these reactions also change over time. While egg and peanut were the primary allergens at age one, children became more sensitive to tree nuts like cashew, hazelnut, walnut, and pistachio by age five.
The study notes that positive allergy tests do not always indicate a lifelong condition. This suggests that a reaction detected at one year might disappear before the child reaches school age.
Knowing if an allergic reaction is lasting or short-lived helps physicians customize therapy. They may modify their strategy depending on whether a trigger is newly appearing, fading, or staying constant. Researchers examined blood from 500 mother-child duos enrolled in a prolonged Canadian cohort. Samples from the kids were collected when they were one year old and again at five.
Researchers tested each sample for 300 different allergen extracts or components to see whether the child had developed any sensitivity. By age one, a quarter of children had sensitivity to at least one food. By age five, this had increased to 2 in 5 children.
Kids also became more sensitized to environmental allergens like cats, dogs, dust mites and grass pollen as they grew older. Sensitization was not always permanent. About 1 in 4 kids lost sensitization to peanut, tree nut and sesame allergen components as they aged. These results could help guide food allergy treatment. For example, doctors might change their approach based on whether a child’s sensitization is new, persistent or disappearing.
SOURCES: Karl Landsteiner University, news release, Oct. 14, 2026; Allergy, Sept. 16, 2026.