What are the other Names of this Condition? (Also known as/Synonyms)

• Allergy to Tree Nuts

What is Tree Nut Allergy? (Definition/Background Information)

• Tree Nut Allergy is a common condition that manifests as an abnormal immune reaction/response to one or more tree nuts, in individuals who consume them
• Tree nuts are hard-shelled nuts obtained from trees and include almonds, walnuts, pistachios, and cashews, among others. Individuals may develop an allergic reaction on consuming tree nuts or related food products
• Raw, processed or roasted tree nuts, oils from tree nuts, butter, salad garnishes, toppings in ice creams, cakes, certain desserts, sauces, energy bars, chocolates, many packaged food products, and flavoring compounds may constitute tree nut foods and related food products
• Tree Nut Allergy may occur immediately, or after a few hours following exposure. The exposure is normally through food ingestion. The condition affects children and adults
• Numerous signs and symptoms of the allergic reaction may be noted including runny nose, hives, itching of the face and mouth, breathing difficulties, nausea and vomiting, and indigestion. In some individuals, Tree Nut Allergy may lead to an anaphylactic shock, which is a medical emergency
• Such food allergies are generally diagnosed using an antibody blood test, a skin-prick test, and an oral food challenge test. The diagnosis can also help identify tree nut based food products that are to be avoided (in future)
• Anti-allergic medications form the first line of treatment for mild Tree Nut Allergies. However, in the case of a severe allergic reaction (anaphylaxis), epinephrine or adrenaline injections are recommended
• The prognosis of Tree Nut Allergy is generally good, although in most individuals it may be present lifelong. Awareness of such allergies and avoidance of specific foods that causes the allergy (via allergen-free foods) is the best form of prevention

Some of the common tree nuts causing allergy include the following (not exhaustive):

• Almonds
• Brazil nuts
• Cashew nuts
• Chestnuts
• Hazelnuts
• Hickory nuts
• Macadamia nuts
• Pecans
• Pistachios
• Pine nuts
• Shea nuts
• Walnuts

Who gets Tree Nut Allergy? (Age and Sex Distribution)

• Tree Nut Allergies can occur in infants, young and old children, including in adults
• No gender preference is noted and both males and females are affected
• All racial and ethnic groups are equally vulnerable to the condition

What are the Risk Factors for Tree Nut Allergy? (Predisposing Factors)

The risk factors for Tree Nut Allergy may include:

• Consuming tree nut products that include the nuts and nut-based food preparations/products
• Any family history of an associated food allergy
• Infants and young growing children are more at risk
• Having one form of (food) allergy puts one at risk for other forms

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Tree Nut Allergy? (Etiology)

An allergic reaction occurs in an individual with Tree Nut Allergy, because the immune system recognizes certain compounds in tree nuts, such as hazelnuts, walnuts, or almonds, as being dangerous and harmful to the body. Many individuals are allergic to more than one type of a tree nut.

• Intake of the tree nut results in the production of antibodies, specifically immunoglobulin E (IgE). The next time the individual is exposed to the same compound, the antibodies that are circulating in blood causes an antibody-antigen reaction
• This results in the production of histamine and other chemical messengers, which cause the symptoms seen during an allergic reaction
• Young children are more prone to the condition, mostly due to an under-developed digestive system
• The quantity of food that triggers an allergy may not be significantly large. Sometimes, consuming tiny amounts of the food item (allergen) is sufficient to trigger Tree Nut Allergy
• Non-food items prepared using tree nuts that may cause an allergy include oils, lotions, hair care products, soaps, certain medications, etc.

In some cases, a severe allergic reaction termed as anaphylaxis may occur, which is a medical emergency that requires immediate medical attention.

What are the Signs and Symptoms of Tree Nut Allergy?

The signs and symptoms of Tree Nut Allergy may start to appear within a few minutes, to a couple of hours, after the individual has consumed tree nut based food products. The symptoms are also common to other types of food allergies. In some, the symptoms are mild, while in others they are severe. Severe symptoms can affect the respiratory and digestive system.

The signs and symptoms of Tree Nut Allergy may include:

• Chills
• Itching of skin, nose, eyes, insides of the mouth
• Urticaria (hives), skin rashes, or eczema
• Coughing, sneezing
• Shortness of breath (trouble breathing), wheezing, asthma-like symptoms
• Swollen eyes, eyelids
• Flushing of face
• Runny or stuffy nose
• Nausea and vomiting
• Diarrhea
• Abdominal distention (bloating) and pain

Generally, not all episodes of allergy will be of the same severity. In some individuals, the most severe symptom caused by the condition is anaphylaxis. Among the various food allergies known and recognized, most cases of anaphylaxis occur from Tree Nut Allergies.

• Anaphylaxis (sometimes called an anaphylactic shock) is a life-threatening, whole-body allergic reaction
• During anaphylaxis, tissues in various body parts release histamine and other messenger chemicals, which causes swelling of the throat and other symptoms
• Swelling of the throat is especially dangerous as this can cause shortness of breath. If the swelling is not reduced soon, then there is a possibility that the individual could die from a lack of sufficient oxygen
• It can also result in a bluish skin, weak pulse, and decreased blood pressure (hypotension)

How is Tree Nut Allergy Diagnosed?

The diagnosis of Tree Nut Allergy may involve the following:

• Physical examination, assessment of symptoms, and medical history evaluation (history of allergies in the family)
• Food diary: Once an allergy is suspected, the healthcare provider may request to maintain a food diary, to note what is being consumed on a regular basis and the corresponding symptoms observed. The healthcare provider can help check which food products are causing allergy, through a process of elimination

The tests that are usually conducted to diagnose Tree Nut Allergy include:

• Oral food challenge testing; when the individual is administered the allergens in a controlled manner to check for symptoms that develop
• Radioallergosorbent (RAS) test; to determine the specific allergy-causing substance
• Skin-prick test:
  • For this test, tiny amounts of certain substances are injected right underneath the skin (forearm, upper arm, or back)
  • After 15-20 minutes, if the spot where the chemical was injected swells, or if there is redness noticed, then this indicates that the individual may be allergic to the substance
• Blood test to detect antibodies (IgE antibody test)

Note: Do-it-yourself allergy testing kits that are commercially available are usually not recommended by healthcare providers.

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Tree Nut Allergy?

The complication of Tree Nut Allergy is associated with the allergic reaction itself and it depends on the severity of the reaction. It may include:

• Anaphylactic shock/reaction that may be life-threatening; a large number of cases of a severe allergic reaction to tree nuts have been reported
• Having one form of allergy can make the individual prone to other allergy types
• In severe reactions, a tracheostomy may have to be performed during an emergency situation

How is Tree Nut Allergy Treated?

The treatment of Tree Nut Allergy may be undertaken in the following manner:

• Avoiding consumption of foods containing tree nuts and related products; elimination diets supervised by a qualified dietitian
• Anti-allergic medication for mild reactions; antihistamine therapy, that is prescribed by the allergy physician
• Symptomatic treatment; use of decongestants, especially for nose block including steroid sprays
• In the case of anaphylaxis (severe allergic reaction), epinephrine or adrenaline is immediately administered
• Breathing support as necessary, control asthma symptoms and low blood pressure
• Immunotherapy, in case of severe allergies, for long-term tolerance development

Provide psychological support to children with such food allergies.

How can Tree Nut Allergy be Prevented?

The best way to prevent Tree Nut Allergy is to avoid tree nut based food products that the individual is allergic to. Additionally, the following factors may be considered:

• Check ingredients of food before using; educate oneself on foods that potentially contain any of the tree nuts
• Parents must be watchful and read food labels, to ensure they do not inadvertently give their child such allergic foods
• Studies have shown that breastfeeding children for 4-6 months or over, can help build their body immunity and make them less prone to allergies
• Appropriate maternal diet during pregnancy can help build stronger resistance (against allergies) in children
• Washing hands with soap and water, in case of contact with an allergen, especially before eating
• Avoiding contaminating food items during food preparation; use separate food utensils for preparing allergy-free meals, when possible
• Use alternatives (such as peanut products, butter made from sunflower), where possible
• While eating out, explain your food allergy to hotel/restaurant service staff and ensure that your food is without the substances you are allergic to
• In hotels and restaurants, separating the preparation of potential food allergens (such as wheat, tree nuts, soy, fish) from general food preparation counters may be beneficial to individuals with food allergies. This can help avoid cross-contact (allergens getting transferred from one food type to another)
• Generating public awareness on various food allergies
• It is important to note that cooking to high-flame or cooking to recommended standards will NOT ensure elimination of the allergen

In case the child or adult is susceptible to an anaphylactic shock (high-risk individuals) from Tree Nut Allergy, the following should be considered:

• Being watchful of triggers and avoiding them
• Wearing medical alert information bracelets or suitable devices
• Carry auto-injector epinephrine or adrenaline medications such as EpiPen, Anapen, or Twinject. Since the condition may recur, it is advised to carry 2 doses (2 pens)
• Supervise children on how to self-administer the injection, if required
• If child is prone to anaphylactic reaction, then information (preferably written instructions) should be given to day care, school authorities accordingly
• Adults should inform their spouses, colleagues, and friends, about the condition, in case of a future emergency

Presently, in many countries, due to labeling and consumer protection laws, foods have suitable labels that indicate their content.

What is the Prognosis of Tree Nut Allergy? (Outcomes/Resolutions)

• The prognosis of Tree Nut Allergy depends on the severity of the signs and symptoms, but it is generally good with suitable treatment. However, only about 10% of the cases are known to resolve by its own
• A vast majority of the individuals have it for the rest of their lives, but are able to cope well with modified diets that exclude tree nuts and tree nut based products
• In some cases, the allergic reaction may be severe, causing anaphylaxis. This is a medical emergency that can lead to a respiratory failure. It requires an immediate treatment of the condition. In such cases, the prognosis is guarded and it depends on whether immediate medical assistance is provided

Additional and Relevant Useful Information for Tree Nut Allergy:

• Peanuts are different from tree nuts; these (peanuts) form on the roots as nodules and are called legumes
• Coconuts are different as well (they are considered as fruits), and nutmeg is a spice (it is not a tree nut)