Allergy to Tree Nuts and Edible Seeds

There is not much information on the prevalence of tree nut allergy in populations, and reports vary in the methods of data collection as well as the ages of the study populations. The few reports available indicate that in the United States, an allergy to tree nuts affects about 0.5% of the population.1 In Canada, the number is 1.22%;2 in the United Kingdom, the number varies from 1.4%3 to 2.2%;4 France reports an incidence of 0.7%;5 Germany 8.5%;6 Sweden 4.1%;7 and Israel 0.03%.8 Previously, it was believed that allergies to tree nuts—including cashews, almonds, Brazil nuts, walnuts, hazelnuts, macadamia nuts, pecans, pistachios, and pine nuts—lasted a lifetime. However, recent research indicates that at least 9% of young children outgrow their nut allergy.9 Even children who have experienced a severe nut allergy can outgrow it. However, the results of the study indicated that children who are allergic to multiple types of tree nuts are less likely to outgrow their allergy than children who are allergic to only one or at most two types of nuts. Based on their results, the study authors recommend that children with tree nut allergies be reevaluated periodically by an allergist/immunologist. They suggest that oral challenges should be considered in children 4 years of age and older who have less than 5 kilounits per liter of tree nut–specific IgE in their blood.