Changes in Tree Nut Sensitization During Avoidance

Abstract

Delayed introduction of some foods in infants increases their risk of food allergy. It is unknown if continued food avoidance carries a similar risk for developing food allergy later in life. We sought to examine patients with initial negative skin prick testing (SPT) to tree nuts who later developed sensitization when tree nuts were not introduced into the diet. We performed a retrospective review of pediatric patients ages 0-18 years at National Jewish Health who had negative SPT to cashew, pistachio, walnut, or pecan with a subsequent positive SPT (wheal ≥10mm) to the same food after ≥1 year of avoidance. Fourteen patients met criteria with ages ranging from 1-13 years (mean 7). Cashew was negative and turned positive in 12 patients (SPT mean 15.3mm, range 10-28mm), and all had similar changes in pistachio (mean 7.8mm, range 2.5-18.5mm). Only two had pistachio SPT ≥10mm at 12.5 and 18.5mm. Walnut was negative and turned positive in 3 patients (SPT mean 13mm, range 10-17.5mm), and all had similar changes in pecan (mean 8.5mm, range 2.5-13.5mm). Only one patient had pecan SPT ≥10mm at 13.5mm. We observed a significant change in sensitization to tree nuts during a period of avoidance, most often with cashew and pistachio. Our findings emphasize the importance of early and regular consumption of tree nuts in the diet if the patient is not sensitized during initial food allergy evaluation to potentially prevent the later development of sensitization.