Allergy Info > Food Allergies > Tree Nut Allergy info

Tree nut allergy is one of the most common types of food allergy, affecting millions of people worldwide. It is a hypersensitivity to dietary substances from tree nuts causing an overreaction of the immune system which may lead to severe physical symptoms^[1]. Tree nuts include Brazil nuts, cashews, chestnuts, filberts/hazelnuts, macadamia nuts, pecans, pine nuts (pignolia nuts), pistachios, and walnuts.

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 a person with a tree nut allergy may not be allergic to all tree nuts. Someone with an allergy to a walnut or pecan may not have an allergy to a cashew or pistachio even though close biological relatives often share related allergenic proteins. The severity of the allergy can vary from person to person and exposure can increase sensitization. For those with a milder form of the allergy, the raw nut protein usually causes a more severe reaction than the oil and extra roasting or processing can reduce the allergic reaction. Those diagnosed with anaphylaxis will have a more immediate mast cell reaction and be required to avoid all exposure to any allergen containing products or byproducts regardless of processing as they are more prone to increased sensitivity. An allergy test or food challenge may be performed at an allergy clinic to determine the exact allergens and new immunotherapy treatments are being developed for tree nut allergy.
Tree nut allergy is distinct from peanut allergy. Peanuts are considered legumes whereas a tree nut is a hard shelled fruit of certain plants. A person with peanut allergies may not necessarily also be allergic to tree nuts, and vice versa.

This allergy tends to be life-long; recent studies have shown that only about 9% of children outgrow their tree nut allergy^[1].

Hazelnut has been used as a model tree nut in the study of tree nut allergies.^[2]

Prevention and treatment

The examples and perspective in this section deal primarily with the United States and do not represent a worldwide view of the subject. Please improve this article and discuss the issue on the talk page. (July 2010)

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^[1]. 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.

Treatment usually involves an exclusion diet and vigilant avoidance of foods that may be contaminated with tree nuts or nut particles and/or oils. The most severe nut allergy reaction is anaphylaxis^[3] and is an emergency situation requiring immediate attention and treatment with epinephrine.