Clinical Information

Allergies to tree nuts are relatively prevalent and can result in severe reactions. The main culprits in tree nut allergies include walnut, almond, pistachio, cashew, pecan, hazelnut, macadamia, Brazil nut, and pine nuts. Tree nut allergy often appears in young children and estimates of prevalence range from 0.1% to greater than 5% of the population, dependent on geographical region.

In the case of nut-induced allergic reactions, as with many other foods, symptoms usually present within minutes of ingestion. Over 80% of reactions to tree nuts involve allergy related respiratory symptoms. Tree nut allergies are one of the most dangerous types of allergic reaction with 20% to 40% of cases of related anaphylaxis, and 70% to 90% of fatalities attributable to nut exposure (including peanut exposure).

Allergy to Brazil nut has reported within the United States population. Among those suffering from tree-nut-allergic individuals, the prevalence of Brazil nut allergy is estimated to be 10% to 20%. Brazil nut allergy occurs primarily through oral ingestion. Following oral exposure, allergy may be associated with systemic reactions, including respiratory and urticaria, occasionally resulting in anaphylaxis.

Ber e 1 is an abundant, heat and digestion resistant, storage protein component that is associated with systemic reactions to Brazil nuts. This major allergen component has been found to correlate with allergic symptoms. Exposure of the Ber e 1 at 100° C for 20 minutes did not to reduce the potential allergenicity of the molecule. 

Immunological cross-reactivity has been reported between Brazil nut, hazelnut, cashew, pistachio, and almond, although cross reactivity with walnut, peanut, and coconut has also been reported. There is considerable homology between the 2S albumin of Brazil nut (Ber e 1) and other plant species, such as cottonseed, sunflower, rapeseed, castor bean, and sesame. Positive antibodies to total Brazil nuts may occur in cases of allergy to other Brazil nut storage proteins, profilins, or in the presence of cross-reacting carbohydrate determinants.