Tree nut allergies are among the most common food allergies for children and adults.
The six tree nut allergies most reported are to walnut, almond, hazelnut, pecan, cashew, and pistachio. These, together with coconut and Brazil nuts, make up the eight most frequent tested tree foods in the global allergy market.
When a person with an allergy to a particular tree nut is exposed, proteins in that nut enter the blood stream after absorption through the small intestine. These proteins then bind to specific IgE antibodies present in the blood. This binding triggers the person’s immune defenses, leading to symptoms that can range from mild to severe. Even very small amounts of tree nut proteins can cause a serious allergic response that could result in potentially life-threatening reactions (anaphylaxis).
The difficulty in these types of allergies is that individuals sensitized to one tree nut food member are routinely allergic to other members within the larger group. For example, approximately two-thirds of patients reactive to cashew or walnut will react to pistachio or pecan, respectively. Similarly, ~50% of children with any tree nut allergy are co-sensitized to other tree-nut food members. Allergen component information can help you better diagnose allergies/sensitizations and prepare personalized management plans. Testing for allergen components allows to distinguish a "true" nut allergy from cross-reactions and provides extensive information about the risk of developing serious reactions when exposed to nuts.
Risk assessment for severe allergic reaction
Components are proteins; protein families are based on homology. Protein families share typical characteristics and can be highly cross-reactive or very specific and vary in stability when heating. These characteristics can be used in allergy risk assessment when testing for components. Heat stable proteins are indicative of a high risk for a severe systemic allergic reaction, whereas heat-labile proteins primarily show local reactions
Storage proteins are stable to heat and digestion, so allergy sufferers are also at risk with roasted/heated preparations. Examples of nut storage allergens: Cashew: Ana o 2, Ana o 3 Hazelnut: Cor a 9, Cor a 11, Cor a 14 Walnut: Jug r 1, Jug r 2, Jug r 4, Jug r 6In contrast, PR-10 proteins of e.g. hazelnut (Cor a 1), are associated with local symptoms such as oral allergy syndrome (OAS) and are markers for birch pollen-associated cross-reactions. These proteins are labile to heat and digestion, so a roasted/heated preparation is usually tolerated. Lipid transfer proteins (nsLTPs) of hazelnut (Cor a 8), walnut (Jug r 3) are frequently associated with severe reactions in addition to oral allergy syndrome. LTPs are stable against heat and digestion and are marker allergens for cross-reactivities to other food LTPs.
Avoidance
Unfortunately, most children who demonstrate this broad reactivity to various tree nuts do not outgrow the sensitivity and the allergy tends to be lifelong. For example, research suggests that only ~9 percent of children with a tree nut allergy will eventually outgrow the sensitization. For this reason, when a sensitized individual is identified, primary care physicians most likely will recommend avoidance of all nuts. Individuals may also be advised to avoid peanuts or peanut-related products due to their likely “cross-contact” with tree nuts at the processing facility. These issues should be discussed and further evaluated with an individual’s allergist and specific allergy testing may be warranted.
Listed below are some of the obvious sources of tree nut allergens that are present in everyday products and consumable, and some less obvious sources:
Obvious sources of exposure:
Obvious sources of tree nuts fall into three main classes of products.
Source nut materials: Source materials include the whole or partial nut but may also include related nut species that may share similar reactivities to the primary sensitivity. For example, individuals with hazelnut allergies typically also cannot eat ginkgo or nangai nuts.
Oils, Flavoring and Extracts: Normally, this category includes processed nuts where flavors, proteins or subcomponents of the larger nut material are separated (extracted) into useful materials for the consumer.
Mixtures, Butters: This group of nuts is also processed; however, the resulting mixture usually is homogenized into a paste before packaging or drying for final use.
Less obvious (hidden) sources of exposure
Nuts can be used in some products that may not resemble the original source material. Tree nut proteins can be found in some surprising places, such as cereals, crackers, cookies, candy, chocolates, energy bars, flavored coffee, frozen desserts, marinades, barbeque sauces and some cold cuts, such as mortadella.
Consumers must be therefore careful when selecting these products because they can cause adverse reactions when exposed.Individuals with allergies may also find unique sensitivities to other products simply because they are related to various tree nuts. For example, although red peppercorn mixes have gained popularity in many culinary circles, these peppercorns contain allergenic proteins that are related to those found in cashews. Individuals who are sensitized to cashew nuts should attempt to avoid peppercorns of these types. In many countries, plain-language labeling on packaged foods is required for different tree nuts. Sensitized individuals must remember to read food or other product labels and ask questions before using the product in their daily lives.
Treatment
If you have a tree nut allergy, many allergists may recommend for the individual to always have access to an epinephrine (adrenaline) injection device. Epinephrine is the first-line treatment for anaphylaxis. Epinephrine is a nonselective alpha- and beta-adrenergic receptor agonist. Through its action on alpha-adrenergic receptors, it reduces vasodilation and increases vascular permeability that occurs during anaphylaxis. Its action on beta-adrenergic receptors results in bronchial smooth muscle relaxation, which helps alleviate bronchospasm, wheezing, and labored breathing that may occur during anaphylaxis. Finally, since epinephrine relaxes smooth muscle of the stomach, intestine, uterus, and bladder, patients will observe less severe itching, redness, and swelling and reduced gastrointestinal and genitourinary symptoms associated with anaphylaxis.
Available tests on NOVEOS:
Whole Allergen extract mixes:
FX01 Nut Mix (Peanut, Hazelnut, Brazil Nut, Almond, Coconut)
FX99 Food Tree Nut Mix (Hazelnut, Almond, Pecan Nut, Cashew Nut, Pistachio Nut, Walnut)
Allergen Components:
F425 rCor a 8 LTP, Hazelnut
F428 rCor a 1 PR-10, Hazelnut
F439 rCor a 14, Hazelnut
F440 Cor a 9, Hazelnut
F441 rJug r 1, Walnut
F442 rJug 3 LTP, Walnut
F443 rAna o 3, Cashew Nut
NOVEOS Allergen Menu List, Specific IgE and Total IgE:
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