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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 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. Many children grow out of food allergies to egg, milk, or soy. It is less likely that children will grow out of peanut or tree nut allergies.

Most healthcare providers warn not to feed your child 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. Symptoms can include:

  • skin reactions such as itching, hives, eczema, or swelling
  • diarrhea, nausea, vomiting, stomach pain or itching around the mouth
  • runny nose, wheezing or trouble breathing
  • fainting
  • 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. It can cause swelling of the mouth and throat, dangerously low blood pressure, and trouble breathing. This type of reaction is a medical emergency. It is treated with epinephrine (a medicine that is given by injection). Usually parents or caregivers of children who have severe allergic reactions carry their own shot kits, just 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.

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. 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.

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.

The first step is to read labels and get familiar with ingredients that contain tree nuts. Reading labels and having an awareness of ethnic and convenience foods that may not have labels is key. Always ask about ingredients if you are not sure. 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 or chili sauce)
  • Baking mixes
  • Cereals
  • meat-free burgers
  • 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 a problem when trying to avoid nuts. Other foods often come in contact with nuts during processing and in preparation. This is true even if nuts are not part of 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:

  • Order simple dishes with only a few ingredients. Avoid sauces unless you're sure they don't contain nuts.
  • Tell the waiter or waitress about the allergy.
  • Ask if food processors, cutting boards, pans, knives, or other food preparation equipment is used for nuts and for other foods.
  • Italian, Asian, African, 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. The challenge is not providing adequate nutrition, but to keep your child from unknowingly eating foods that contain them.

You can make desserts from scratch or mixes that do not contain nuts. Some companies make products without nuts. They also have processes to avoid the risk of cross-contamination with nuts. This would be stated clearly on the label.

How can I keep my child safe at school?

  • Teach your child not to eat foods unless they are safe. Even young children can grasp this concept, especially once they have gotten sick after eating a particular food.
  • Prepare your child's lunch at home.
  • 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 if needed.
  • Have the teacher call you if there is a special event or party planned. That way you can bring treats that your child can eat and 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 life-threatening anaphylactic reactions before should keep injectable epinephrine (such as EpiPen) and an antihistamine (such as Benadryl) with them at all times.

Written by Terri Murphy, RD, CDE for RelayHealth.
Published by RelayHealth.
Last modified: 2010-01-27
Last reviewed: 2010-01-11

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 health care professional.

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