Allergies to tree nuts and seeds tend to be of a more severe nature, causing life-threatening and sometimes fatal reactions. People with tree nut allergies also often suffer from reactions triggered by a number of different types of nuts, even though they do not come from closely related plant species. In general these allergies are triggered by the major proteins found in nuts and seeds which are resist processes such as cooking.
There is also a milder form of tree nut allergy which is associated with birch pollen allergy, where symptoms are confined largely to the mouth, causing a condition called “oral allergy syndrome” (OAS). This condition is triggered by molecules found in tree nuts which are very similar to pollen allergens like the major birch pollen allergen called Bet v 1. These molecules tend to be destroyed by cooking, which can reduce the allergenicity of nuts and seeds for these allergic consumers.
Reactions to nuts and seeds can also occur as a consequence of hidden nut ingredients or traces of nuts and certain seeds introduced as a consequence of food handling or manufacturing. As a result tree nuts and seeds have been included in Annex IIIa of the EU food labelling directive. The following (including products thereof) must be declared on a label if they have been deliberately included in a food:
Almond, hazelnut, Walnut, Cashew, Pecan nut, Brazil nut, Pistachio nut, Macadamia nut Queensland nut, Mustard and Sesame seeds
Temporary exceptions to the labelling rule (derogations) have been granted for