Tree nut allergy

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A tree nut allergy is a hypersensitivity to dietary substances from tree nuts and edible tree seeds causing an overreaction of the immune system which may lead to severe physical symptoms. Tree nuts include, but are not limited to, almonds, Brazil nuts, cashews, chestnuts, coconuts, filberts/hazelnuts, macadamia nuts, pecans, pistachios, pine nuts, shea nuts and walnuts.

Tree nut allergies are distinct from peanut allergy, as peanuts are legumes, whereas a tree nut is a hard-shelled nut.

Video Tree nut allergy

Signs and symptoms

The severity of the allergy varies from person to person, and exposure can increase sensitization. For those with a milder form of the allergy, a reaction which makes the throat feel like cotton may occur. Subjects allergic to tree nut can experience asthma, skin rashes, itchy throat, swollen eyes. The most severe reaction can lead to anaphylaxis.

The raw nut protein usually causes a more severe reaction than the oil, and extra roasting or processing can reduce the allergic reaction.

This allergy tends to be lifelong; studies have shown that only about 9% of children outgrow their tree nut allergy.

Maps Tree nut allergy

Cause

People with tree nut allergy are seldom allergic to just one type of nut, 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.

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Diagnosis

An allergy test or food challenge may be performed at an allergy clinic to determine the exact allergens.

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Prevention

Prevention involves an exclusion diet and vigilant avoidance of foods that may be contaminated with tree nuts, nut particles, or oils extracted from nuts. In the United States, the federal Food Allergen Labeling and Consumer Protection Act (FALCPA) requires that any packaged food product that contains tree nuts as an ingredient must list the specific tree nut on the label. Foods that almost always contain tree nuts include pesto, marzipan, Nutella, baklava, pralines, nougat, gianduja, and turrón. Other common foods that may contain tree nuts include cereals, crackers, cookies, baked goods, candy, chocolates, energy/granola bars, flavored coffee, frozen desserts, marinades, barbecue sauces, and some cold cuts, such as mortadella. Tree nut oils (especially shea nut) are also sometimes used in lotions and soaps. Asian and African restaurants, ice cream parlors, and bakeries are considered high-risk for people with tree nut allergy due to the common use of nuts and the possibility of cross contamination.

Cross-reactivity

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. 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 to peanuts and other legumes. 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.

Regulation of labeling

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. The U.S. Food Allergen Labeling and Consumer Protection Act of 2004 (FALCPA) requires companies to disclose on the label whether the product contains a major food allergen added intentionally: cow's milk, peanuts, eggs, shellfish, fish, tree nuts, soy and wheat. This list originated in 1999 from the World Health Organisation Codex Alimentarius Commission. FALCPA applies to foods regulated by the FDA, which does not include poultry, most meats, certain egg products, and most alcoholic beverages. The allergens have to clearly be called out in the ingredients list. Most companies selling food products in the United States additionally list ingredient allergens in a separate statement. To meet FALCPA labeling requirements, when an ingredient is derived from a major food allergen, its "food source name" must appear in the list of ingredients. For example, casein as an ingredient must appear as "casein (milk)" in the list of ingredients. Dairy food listing is also mandatory in the European Union and more than a dozen other countries.

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.). 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.

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. PAL labeling can be confusing to consumers, especially as there can be many variations on the wording of the warning. 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. 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" (ED01) as 0.01 mg for hazelnut protein. There was not sufficient information to set an ED01 for other tree nuts. This hazelnit threshold reference dose (and similar results for 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." VITAL 2.0 was developed by the Allergen Bureau, a food industry sponsored, non-government organization. The European Union has initiated a process to create labeling regulations for unintentional contamination but is not expected to publish such before 2024.

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Treatment

Severe reactions are typically treated with adrenaline by injectors, and those with a history of allergies are recommended to carry injectors at all times. Less severe reaction may be dealt with by taking antihistamines tablet.

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Society and culture

Whether food allergy prevalence is increasing or not, food allergy awareness has increased, with impacts on the quality of life for children, their parents and their immediate caregivers. In the United States, the Food Allergen Labeling and Consumer Protection Act of 2004 causes people to be reminded of allergy problems every time they handle a food package, and restaurants have added allergen warnings to menus. The Culinary Institute of America, a premier school for chef training, has courses in allergen-free cooking and a separate teaching kitchen. School systems have protocols about what foods can be brought into the school. Despite all these precautions, people with serious allergies are aware that accidental exposure can easily occur at other peoples' houses, at school or in restaurants. Food fear has a significant impact on quality of life. Finally, for children with allergies, their quality of life is also affected by actions of their peers. There is an increased occurrence of bullying, which can include threats or acts of deliberately being touched with foods they need to avoid, also having their allergen-free food deliberately contaminated.

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Research

Immunotherapy treatments are being developed for tree nut allergy.

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See also

• Allergy (has diagrams showing involvement of different types of white blood cells)
• Food allergy (has images of hives, skin prick test and patch test)
• List of allergens (food and non-food)
• Peanut allergy (can be cross-reactive to tree nut allergy)

Notes

References

External links

• Tree nut allergy at Food Allergy Initiative
• "Are Nut Bans Promoting Hysteria?" by Tana Parker-Pope at The New York Times (15 Dec 2008)

Source of the article : Wikipedia