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Tree Nut Allergy: Symptoms and Foods to Avoid

Proteins found in many different types of tree nuts are a common cause of food allergy known as tree nut allergy. About 1% of the population suffer from tree nut allergies. Tree nuts are the hard, oily seeds of some trees, eaten raw or roasted, added to foods and sometimes also used to make edible oils. Tree nuts and their derivatives can be found in a variety of different foods as well as non-consumable products ranging from topical creams to shampoos.

Paradoxically, peanuts are not a type of nut but legumes like beans or peas, though some individuals allergic to tree nuts may be also allergic to peanuts. Other foods with the word “nut” in them that are not tree nuts include coconut (fruit), water chestnut (fruit), ginger nut (cookie) and nutmeg (spice).

Cooking, roasting or processing tree nuts does not reduce the allergic response they induce. Just like a peanut allergy, tree nut allergies can be triggered by a very tiny amount of offending substance (i.e., tree nut protein), much smaller than other food allergies. Often, simply kissing or having skin-to-skin contact with someone who has just eaten tree nuts can cause an allergic reaction in very sensitive individuals.

Causes of Tree Nut Allergies

Even the tiniest amount of tree nut protein in the ingredients of a consumed food can trigger an allergy in sensitive individuals. Less commonly, an allergic reaction can occur when touching or inhaling the tree nut protein. The most common tree nuts used in the food industry include:

  • Almonds
  • Beechnuts
  • Brazil nuts
  • Cashews
  • Chestnuts
  • Filberts
  • Hazelnuts
  • Hickory nuts
  • Macadamia nuts
  • Pecans
  • Pine nuts (Pignoli nuts, Pinion)
  • Pistachios
  • Walnuts

Allergic people must be careful to avoid products and processed foods that contain tree nuts and ingredients with tree nut proteins such as those listed below:

  • Baking mixes
  • Cakes (especially fruit and nut rolls, carrot cake, pumpkin cake or pie)
  • Candy (chocolate)
  • Certain vegetarian dishes
  • Chili
  • Chinese, Malaysian, Thai, Vietnamese, African, Mexican and other ethnic dishes (these traditionally include tree nuts or peanuts)
  • Cookies, pastries and other baked goods
  • Crackers
  • Doughnuts
  • Egg rolls
  • Frozen deserts
  • Grain breads
  • Gravy
  • Health food bars
  • Mandelonas (peanuts soaked in almond flavoring)
  • Marzipan (almond paste)
  • Nougat
  • Nut butters (such as cashew butter and almond butter)
  • Nut extracts (almond extract)
  • Nut meal
  • Nutmeat
  • Nut oils
  • Nut paste
  • Pesto
  • Praline
  • Salad dressing
  • Sauces (e.g., barbecue, curry, bouillon, Worcestershire)
  • Some cereals including muesli, granola and fruited cereals
  • Stuffing
  • Used oils (that may have been used to fry food containing tree nuts)

Lotions, cosmetic creams, soaps, shampoos and conditioners may also contain tree nut proteins. People with three nut allergies can experience an allergic response to these substances by absorbing the offending protein through the skin.

There may be food products that do not normally contain tree nuts but are cross-contaminated with tree nut proteins by the machinery in factories or the appliances in restaurants. Sometimes, the food label may include a statement that the food was processed on equipment that also processes foods containing nuts, though this statement is not mandatory. When in doubt about a product, allergic individuals should better avoid using or consuming such product.

In some extremely sensitive individuals, an allergic reaction can be induced just by touching or kissing another person who has recently consumed nuts or by inhaling the fumes produced by cooking nuts.

There have been reports of some types of seeds triggering allergic reactions in patients with tree nut allergies. In fact, tree nuts are just large, edible seeds, therefore, individuals sensitive to tree nuts should be suspicious of all seeds in general. More specifically, it may be prudent to avoid poppy seeds, sesame seeds, sunflower seeds and pine kernels.

Those with a history of asthma, other food and pollen allergies and eczema are more likely to have a tree nut allergy. Also, heredity seems to play a role. Such people appear to be more susceptible to a severe or life-threatening reaction like anaphylactic shock.

Related Allergies and Conditions

Patients with an allergy to certain types of tree nuts may find they also have reaction to other types of tree nuts. This is known as a cross-reaction. In addition, it is quite common for people with a tree nut allergy to be also allergic to peanuts, which are a type of legume, not a nut. Therefore, tree nut-allergic individuals need to use caution when consuming any type of nut or peanuts.

Patients allergic to tree nuts are at an increased risk for oral allergy syndrome characterized by an itching or swelling in the throat, palate, tongue or lips after consuming certain foods at certain times of the year. This is because of a similarity between a specific type of protein found in the food and in certain types of pollen.

There are several conditions that may be mistaken for a tree nut allergy such as food poisoning and food intolerances, sensitivity to food additives (e.g., flavorings or preservatives like MSG and sulfites), irritable bowel syndrome and various other gastrointestinal conditions.

Symptoms of Tree Nut Allergies

Exposure to tree nuts can provoke a host of symptoms in allergic individuals. Symptoms often appear immediately after ingesting a tree nut or tree nut product, though they can also begin up to four hours later and may reoccur in several hours after the initial reaction has subsided with a second wave of symptoms. The most typical symptoms of a tree nut allergy include:

  • Redness
  • Tingling feeling in the lips and mouth
  • Cramping stomach pains
  • Vomiting or diarrhea
  • Itchy hives (urticaria), mostly when nuts make skin contact
  • Swelling of the skin (angioedema), primarily when nuts make skin contact
  • Swelling in the throat (causing swallowing or breathing difficulties)
  • Shortness of breath
  • Dizziness, faintness or unconsciousness

Reactions associated with a tree nut allergy range from mild anaphylaxis (symptoms from two or more areas of the body) to severe and potentially life-threatening anaphylactic shock characterized by constriction of the air passageways and a dangerous drop in blood pressure.

In addition, there are a number of reports of allergic contact dermatitis caused by cashew nut shell oil. In fact, the cashew tree comes from the same family of plants as poison oak, poison ivy and poison sumac.

Diagnosing Tree Nut Allergies

To diagnose a tree nut allergy, the doctor will first need to rule out other conditions with similar symptoms. Patients may be asked to keep a food diary for several weeks or months to document allergic reactions to the foods they eat. This should help the doctor to identify the type of allergen. In general, all tests used to diagnose tree nut allergies are very similar to those used for other food allergies as described in the previous article.

Treatment and Prevention of Tree Nut Allergies

The only effective way of preventing an allergic reaction to tree nuts is the complete avoidance of tree nuts and all products containing tree nut proteins and oils. For more information on treating and preventing food allergies similar to tree nut allergies and relieving their symptoms, please refer to this article.