Tree nut allergy

People with clinically confirmed tree nut allergy to one type of tree nut may have cross-reactivity to other tree nut species and also to peanuts, which are not nuts but rather part of the legume family.[15][16] The cause is similarity in protein structures. Identifiable allergenic proteins are grouped into families: cupins, prolamins, profilin and others. Tree nuts have proteins in these families, as do peanuts and other legumes.[15] Reviews of human trials report that for a confirmed tree nut allergy, up to one third of people will react to more than one type of tree nut. The cross reactivity among almond, walnut, pecan, hazelnut and Brazil nut is stronger than cross reactivity of these toward cashew or pistachio.[16]

People with tree nut allergy are seldom allergic to just one type of nut,[17][18] and are therefore usually advised to avoid all tree nuts, even though an individual may not be allergic to the nuts of all species of trees.

Someone allergic to walnuts or pecans may not have an allergy to cashews or pistachios, because the two groups are only distantly related and do not necessarily share related allergenic proteins.[19]

An example of a list of allergens in a food item

In response to the risk that certain foods pose to those with food allergies, some countries have responded by instituting labeling laws that require food products to clearly inform consumers if their products contain major allergens or byproducts of major allergens among the ingredients intentionally added to foods. Nevertheless, there are no labeling laws to mandatory declare the presence of trace amounts in the final product as a consequence of cross-contamination, except in Brazil.[5]

[26][29][30][31][32][4][3]

FALCPA requires companies to disclose on the label whether a packaged food product contains any of these eight major food allergens, added intentionally: cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy and wheat.[26] This list originated in 1999 from the World Health Organisation Codex Alimentarius Commission.[4] To meet FALCPA labeling requirements, if an ingredient is derived from one of the required-label allergens, then it must either have its "food sourced name" in parentheses, for example "Casein (milk)," or as an alternative, there must be a statement separate but adjacent to the ingredients list: "Contains milk" (and any other of the allergens with mandatory labeling).[26][30] The European Union requires listing for those eight major allergens plus molluscs, celery, mustard, lupin, sesame and sulfites.[29]

FALCPA applies to packaged foods regulated by the FDA, which does not include poultry, most meats, certain egg products, and most alcoholic beverages.[3] However, some meat, poultry, and egg processed products may contain allergenic ingredients. These products are regulated by the Food Safety and Inspection Service (FSIS), which requires that any ingredient be declared in the labeling only by its common or usual name. Neither the identification of the source of a specific ingredient in a parenthetical statement nor the use of statements to alert for the presence of specific ingredients, like "Contains: milk", are mandatory according to FSIS.[31][32] FALCPA also does not apply to food prepared in restaurants.[33][34] The EU Food Information for Consumers Regulation 1169/2011 – requires food businesses to provide allergy information on food sold unpackaged, for example, in catering outlets, deli counters, bakeries and sandwich bars.[35]

The value of allergen labeling other than for intentional ingredients is controversial. This concerns labeling for ingredients present unintentionally as a consequence of cross-contact or cross-contamination at any point along the food chain (during raw material transportation, storage or handling, due to shared equipment for processing and packaging, etc.).[4][3] Experts in this field propose that if allergen labeling is to be useful to consumers, and healthcare professionals who advise and treat those consumers, ideally there should be agreement on which foods require labeling, threshold quantities below which labeling may be of no purpose, and validation of allergen detection methods to test and potentially recall foods that were deliberately or inadvertently contaminated.[36][37]

Labeling regulations have been modified to provide for mandatory labeling of ingredients plus voluntary labeling, termed precautionary allergen labeling (PAL), also known as “may contain” statements, for possible, inadvertent, trace amount, cross-contamination during production.[4][38] PAL labeling can be confusing to consumers, especially as there can be many variations on the wording of the warning.[38][39] As of 2014 PAL is regulated only in Switzerland, Japan, Argentina, and South Africa. Argentina decided to prohibit precautionary allergen labeling since 2010, and instead puts the onus on the manufacturer to control the manufacturing process and label only those allergenic ingredients known to be in the products. South Africa does not permit the use of PAL, except when manufacturers demonstrate the potential presence of allergen due to cross-contamination through a documented risk assessment and despite adherence to Good Manufacturing Practice.[4] In Australia and New Zealand there is a recommendation that PAL be replaced by guidance from VITAL 2.0 (Vital Incidental Trace Allergen Labeling). A review identified "the eliciting dose for an allergic reaction in 1% of the population" as ED01. This threshold reference dose for foods (such as cow's milk, egg, peanut and other proteins) will provide food manufacturers with guidance for developing precautionary labeling and give consumers a better idea of might be accidentally in a food product beyond "may contain."[40][41] VITAL 2.0 was developed by the Allergen Bureau, a food industry sponsored, non-government organization.[42] The European Union has initiated a process to create labeling regulations for unintentional contamination but is not expected to publish such before 2024.[43]

In Brazil since April 2016, the declaration of the possibility of cross-contamination is mandatory when the product does not intentionally add any allergenic food or its derivatives, but the Good Manufacturing Practices and allergen control measures adopted are not sufficient to prevent the presence of accidental trace amounts. These allergens include wheat, rye, barley, oats and their hybrids, crustaceans, eggs, fish, peanuts, soybean, milk of all species of mammalians, almonds, hazelnuts, cashew nuts, Brazil nuts, macadamia nuts, walnuts, pecan nuts, pistaches, pine nuts, and chestnuts.[5]