Tree Nut Allergy

What is a tree nut allergy?

Tree nuts include all nuts that grow on trees (such as walnuts and cashews). A tree nut allergy is a reaction by your child's immune system to tree nuts. Our immune systems normally respond to invaders that attack the body such as bacteria or viruses. A food allergy occurs when the body's immune system mistakenly believes that a harmless food substance (such as tree nut proteins) is harmful. In order to protect the body, the immune system creates substances called antibodies to that food. The next time you eat that particular food, your immune system releases huge amounts of chemicals, such as histamines, to protect the body. This is what causes the warning symptoms.

Tree nuts are among the 8 foods responsible for most food allergies in children. The other foods include milk, soy, eggs, peanuts, wheat, fish, and shellfish. It is common for children to grow out of food allergies such as to egg, milk, or soy, but less likely for people grow out of a peanut or tree nut allergy.

Most healthcare providers warn not to feed children highly allergic foods, such as shellfish, and food containing peanuts and tree nuts, until age 2. If you have a family history of allergies, some recommend waiting until 3 years.

What are the symptoms of an allergic reaction to tree nuts?

If you suspect your child is having an allergic reaction to nuts or any other food, it is important to get a diagnosis from your healthcare provider or allergist. You should look for the following symptoms, which can be severe:

  • skin reactions such as itching, hives, eczema or swelling
  • diarrhea, nausea, vomiting, stomach pain or itching around the mouth
  • running nose, wheezing or trouble breathing
  • rapid heartbeat.

With a tree nut or peanut allergy, it is more common to have an anaphylactic reaction. This is a serious reaction that is sudden, severe, and can involve the whole body. The reaction can cause swelling of the mouth and throat, dangerously lower blood pressure, and closure of the airways leading to trouble breathing. This type of reaction calls for immediate medical attention. It is treated with epinephrine (a medicine that is given by a shot). Typically parents or caregivers of children that have severe reactions to allergies carry their own injection kits in case of emergency.

An allergic reaction to a food usually starts within minutes but may be delayed 2 to 4 hours. It usually lasts less than 1 day. The more severe the allergy, the smaller the amount of food it takes to cause a reaction.

Is my child also allergic to peanuts?

Peanuts grow underground and are not considered to be a "true nut." Peanuts are in the legume family (peas and lentils are also legumes). Nuts such as walnuts, almonds, pecans and cashews grow on trees. About half of the people with a peanut allergy are also allergic to tree nuts. You'll need to check with your healthcare provider whether it is safe for your child to eat peanuts. Dietary restrictions for those with peanut allergy are more difficult to follow because so many processed foods and ethnic foods contain peanuts and peanut products.

How will this affect my child's diet?

The only way to not have a reaction is to avoid the food that causes the allergy symptoms. Your child will need to avoid all sources of tree nuts. If you are breast-feeding, eliminate the food your child is allergic to from your diet. Food allergens can be absorbed from your diet and enter into your breast milk. You will need to change the way you shop for, prepare, and order food. Be sure to check the ingredients on food package labels and ask the waiter about how foods are prepared when dining away from home.

The first step is to be informed about all the ingredients that indicate the presence of a tree nut. Reading labels and having an awareness of ethnic and convenience foods that may not have labels is key. If you are unsure, call the food manufacturer at the 800 number provided on the label. When in doubt, don't use the product.

Nuts and foods that contain nuts

  • Mixed nuts
  • Artificial nuts (can be peanuts that have been re-flavored with another nut, such as walnut or almond)
  • Almonds, cashews, filbert/hazelnuts, chestnuts, pecans (Mashuga nuts), walnuts, pistachio, Brazil, hickory, macadamia nuts
  • Pine nuts (also called Indian, pinon, pignoli, pignon, pignolia nuts)
  • Mandelonas (peanuts soaked in almond flavoring)
  • Marzipan/almond paste
  • Nan-gai nuts
  • Nut butters
  • Natural nut extract
  • Nut pieces
  • Nut meat, nut meal, nut oil, or nut paste
  • Pesto (contains pine nuts, but often other nuts are substituted)
  • Gianduja (nut mixture in some chocolate)
  • Caponata (Italian dish made with pignolia nuts)
  • Pralines and nougat.

Nutmeg is safe (made from the seed of a tropical plant) and coconut is usually safe, but it is wise to consult your healthcare provider first. Note that non-food items such as Hacky Sacks (kick sacks) and beanbags are sometimes filled with crushed nutshells. Inquire about the filling before purchasing.

Foods that often contain nuts

  • Sauces (such as barbecue)
  • Baking mixes
  • Cereals
  • Prepared salads and salad dressings
  • Hydrolyzed vegetable protein (usually soy based, but may come from any non-animal source)
  • Emulsified ingredients (may have been thickened with nuts)
  • Natural and artificial flavorings may contain tree nuts and are used in many foods, such as crackers, cereals, sauces, and ice cream.

Hidden sources of nuts

Cross contamination is one of the biggest problems when trying to avoid nuts. It is common for nuts to come in contact with other foods during processing and in preparation, even if the nut is not included in the recipe.

The following foods are sometimes contaminated with nuts:

  • Chocolate candies and ice cream
  • Pastries, cookies, and cakes where ingredients aren't listed.

When dining out, always tell the waitperson about the allergy and order simple dishes without sauces unless you're sure there are no nuts present. Cross contamination can be a problem in restaurants.

  • Food preparation equipment (such as food processors, cutting boards, pans and knives) may be used for nuts as well as for other recipes.
  • Italian, Chinese and Vegetarian dishes often include nuts.
  • Pure refined nut oil, if properly processed, should not contain nut protein and therefore should not cause reactions in allergic children. However, nut oils are also available unrefined. Unrefined oils may be called cold-pressed, unprocessed, expelled or extruded oils. These unrefined oils may have nut proteins and could cause allergic reactions. If in doubt, call the manufacturer.

Reading labels to avoid allergens has become a lot easier. Foods that contain milk, eggs, fish, shellfish, peanuts, tree nuts, wheat, or soy products must list the food in plain language on the ingredient list. For example, marzipan (almond). The specific tree nut (almond, cashew, walnut) must be clearly stated. These possible allergens must be listed even if they are part of a flavoring, coloring, or spice blend. There are still some things to watch out for when reading food labels:

  • Read the label every time. The manufacturer may change ingredients.
  • Watch out for the words "may contain". Milk, peanuts, or other allergens may not be ingredients, but the food may be made in a factory that also produces these foods. If you see the words "may contain", there may be very little of the allergen, or there may be a large amount.
  • Words on the package such as "peanut free" or "milk free" do NOT mean that the food is completely without these allergens. You still need to read the label carefully to make sure that it does not contain ingredients derived from allergens.

It is very important for you to know less common names and scientific names for food ingredients.

How can I provide my child with a healthy diet that tastes good?

Your child can still have a nutritionally complete diet. The primary nutrients found in nuts are protein, healthy fats, fiber, vitamin E, and magnesium. There are many other foods that contain the same nutrients as tree nuts, so the challenge is not providing adequate nutrition, but to keep your child from unknowingly eating foods that contain them. You can prepare desserts from scratch or mixes you know don't contain nuts. Some ice cream and chocolate companies make products without nuts and that have been processed separately from those prepared with nuts to eliminate the risk of "cross-contamination." This would be stated clearly on the label.

How can I keep my child safe at school?

  • Prepare your child's lunch at home.
  • Educate your child to the dangers of sharing foods (even young children can grasp this concept, especially once they have experienced feeling sick after eating a particular food).
  • Talk with teachers and the school administrator regarding your child's needs. Request that teachers keep an eye out and explain the situation to other children when appropriate.
  • Have the teacher call you if there is a special event or party planned so that you can bring a few modified treats that your child enjoys and can share with other kids.
  • Make a card that lists foods and ingredients that should be avoided and give one to the teacher. The card can also be helpful to older children in making decisions when out with friends.
  • Children who have had previous life-threatening anaphylactic reactions should have access at all times (including school) to an injectable epinephrine and an antihistamine (such as Benadryl).
Written by Terri Murphy, RD, CDE for RelayHealth.
Published by RelayHealth.
Last modified: 2009-01-22
Last reviewed: 2008-11-11
This content is reviewed periodically and is subject to change as new health information becomes available. The information is intended to inform and educate and is not a replacement for medical evaluation, advice, diagnosis or treatment by a healthcare professional.
© 2009 RelayHealth and/or its affiliates. All Rights Reserved.