Learn what tree nut allergies are, how allergists diagnose them, how to manage them, and what foods a tree nut allergic child will need to avoid.
Tree nut allergy is one of the eight most common food allergies in the United States. Today, we’ll cover everything parents need to know about tree nut allergies, including:
- What counts as a tree nut allergy, including types of tree nut allergies
- Symptoms of tree nut allergies
- How allergists diagnose tree nut allergy
- How to manage tree nut allergies
- What foods a child with a tree nut allergy will need to avoid
- What foods aren’t related to tree nuts
What is a tree nut allergy?
Tree nut allergies are a wide category of food allergy. The category includes, but is not limited to, allergies to:
- Hazelnuts (also called filberts)
- Brazil nuts
- Macadamia nuts
- Pine nuts (also called pinon)
- Hickory nuts
Someone with a tree nut allergy could have an allergy to 1, 2, or several types of tree nuts.
What happens in the body when someone has a tree nut allergy?
Normally, our immune systems defend and protect us from foreign invaders, like certain viruses and bacteria.
But if your child has a tree nut allergy, their immune system mistakenly treats the proteins in certain types of tree nuts as foreign invaders. Their immune system over-defends their body against a type or types of tree nut.
Their immune system makes special allergy antibodies, called IgE antibodies, that are designed to fight off specific types of tree nut proteins. These antibodies trigger a reaction each time your child consumes a tree nut product that they are allergic to.
Specific tree nut IgE antibodies are narrowly focused, so they won't trigger an allergic reaction to every single type of tree nut.
For example, if your child has a walnut allergy, their body makes IgE antibodies that detect and fight off walnut proteins, and that cause an allergic reaction when your child consumes walnuts.
But these walnut IgE antibodies won't trigger an allergic reaction if your child consumes pistachio. Their body would need to have specific pistachio IgE antibodies for the child to also have a pistachio allergy.
This is why most people with tree nut allergies don't have allergic reactions to every single type of tree nut, and many only have allergic reactions to 1 or 2 types.
Symptoms of a Tree Nut Allergy
An allergic reaction to tree nuts could range from mild to severe, and could be life-threatening.
Allergies to all types of tree nuts cause similar symptoms. Some of the common symptoms of a tree nut allergy reaction include:
- Eyes: Itchy, red, or watery eyes
- Mouth: Itching in or around the mouth, swelling of the lips, swelling of the tongue
- Skin: Hives, swelling, red rash, itchy skin
- Respiratory: Sneezing, runny nose, nasal congestion, coughing, chest tightness, throat tightness, difficulty breathing, wheezing
- Gastrointestinal: Stomach pain, vomiting, diarrhea, gas, nausea
- Cardiovascular: Fast heartbeat, low blood pressure, dizziness, fainting
These symptoms usually develop seconds to minutes after someone consumes a tree nut they’re allergic to, and almost always develop within 2 hours.
When a tree nut allergy reaction involves severe symptoms in more than one organ system, this is known as anaphylaxis. Anaphylaxis can be life-threatening. Swelling of the face, throat, or tongue, difficulty breathing, wheezing, and significant cardiovascular symptoms may be signs of an anaphylactic reaction. if your child shows any signs of anaphylaxis, immediately call 911, and immediately give epinephrine (use an Epi-Pen).
Tree Nut Allergy Testing
Skin prick tests, blood tests, and oral food challenges are the three ways to test for a tree nut allergy. All are supervised by an allergist, and all test for specific types of tree nut allergies.
- When your child takes a skin prick test, an allergist pricks their forearm with a needle containing a specific tree nut protein. Then, the allergist closely monitors your child to see if an allergic reaction develops around the area where the skin was pricked.
- When your child takes a blood test, their blood is checked for IgE antibodies that respond to specific tree nut proteins.
- During an oral food challenge, your child eats small amounts of a specific tree nut under allergist supervision, to see if they develop an allergic reaction. This is the most accurate way to diagnose a tree nut allergy, but your child will need to take a different food challenge for each tree nut that they have a suspected allergy to.
Tree Nut Allergy Trends
Tree nut allergies are one of the 8 most common food allergies. When all the different types of tree nut allergies are counted together, tree nut allergies are estimated to affect around 1% of the general population.
According to FARE, the six most common tree nut allergies (in children and adults) are allergies to walnut, almond, hazelnut, pecan, cashew and pistachio.
Tree nut allergies are usually lifelong. Most children don’t outgrow their tree nut allergy as they get older. FARE reports that only around 9% of children outgrow their tree nut allergy.
If my child is allergic to one tree nut, do they need to avoid all tree nuts?
Even though "tree nut allergies" includes allergies to many types of nuts, if someone is allergic to one tree nut, that doesn't mean they are allergic to all tree nuts.
Certain tree nuts are closely related, though.
Cashews and pistachios are closely related, and pecans and walnuts are closely related, since their proteins are very similar to each other.
Because of this, developing an allergy to one tree nut may make someone more likely to develop an allergy to a closely related tree nut. This is known as cross-reactivity.
Why does cross-reactivity happen? The proteins in closely related types of tree nuts are so similar to each other that someone's immune system may start to treat these proteins exactly the same. This may cause an allergic reaction when specific IgE antibodies detect the proteins from either closely related tree nut. But not everyone with a tree nut allergy will experience cross-reactivity.
And even if cross-reactivity comes into play, many people with tree nut allergies are still only allergic to 1 or 2 types of tree nuts.
So, it's worth working with an allergist to determine if your child can safely eat other types of tree nuts. Every child is different---your allergist will help you make an individualized plan for their unique needs. Until you’ve talked with an allergist, though, you may decide it’s safest to keep your child away from all types of tree nuts.
Tree Nut Allergy Management
If your child has a tree nut allergy, they'll need to avoid all foods that contain the tree nut(s) they are allergic to. Eating even a small amount of a tree nut that they are allergic to could cause them to develop an allergic reaction.
Along with peanut allergies, tree nut allergies are one of the food allergy types most likely to cause severe reactions. Since tree nut allergy reactions could become life-threatening, it’s vital for you and your child to have epinephrine (an Epi-pen or Auvi-Q) nearby at all times. Epinephrine is the only medicine that can stop anaphylaxis.
Learn more about tree nut allergy from Food Allergy Research & Education (FARE):
Since tree nut allergies are one of the 8 major allergens in the United States, food manufacturers must clearly identify if a food contains tree nuts on the label.
A manufacturer must also point out the specific type(s) of tree nut(s) that a food contains on the label. They're required to do so under federal law.
For example, if a food contains almonds, almonds must be listed as an ingredient. It’s not enough for a label to just say “contains tree nuts.”
Even so, avoiding tree nuts can still get complicated because many foods contain hidden tree nuts---and because every tree nut is different.
Some foods that may contain hidden tree nuts include:
- Trail mix
- Barbecue sauce and other sauces
- Baked desserts, including cookies, grain breads, macarons and pie crusts
- Frozen desserts, such as ice cream
- Other desserts, like pudding
- Pesto (it almost always contains pine nuts)
Read food labels carefully to check for the tree nut(s) your child is allergic to!
Also remember to avoid these ingredients:
- Tree nut oils
- Tree nut butters (including Nutella, which contains hazelnuts)
- Tree nut flours
- Tree nut pastes (including marzipan, which is almond paste)
- Natural tree nut extracts
- Nut milks (ex. almond milk, cashew milk)
- Even “artificial nuts” sometimes contain tree nuts!
Even if a food at a restaurant or other location doesn’t contain the tree nut your child is allergic to, there’s still a risk of cross-contamination. Cross-contamination is the accidental mixing of a food with tree nuts into a food without tree nuts.
You'll need to watch out for foods that were processed on the same equipment as foods that contain tree nuts. (These foods will say "may contain tree nuts" on their labels. “May contain” labeling isn’t required to identify specific tree nuts.)
As FARE reports, Chinese, Thai, Vietnamese, Indian and African restaurants, bakeries and ice cream parlors are usually environments with a high risk for cross-contamination, as these locations regularly use tree nut ingredients. Even if you order a food without tree nuts, there’s a high risk that a tree nut was accidentally mixed into the food.
Are tree nut allergies related to peanut allergies?
Tree nut allergies are a completely different allergy category from peanut allergies. Peanuts are legumes that grow under the ground, not nuts that grow on trees.
Even so, peanut allergies and tree nut allergies seem to be closely connected. 30% of people with peanut allergies are also allergic to tree nuts.
Having a tree nut allergy doesn't mean that someone will also be allergic to peanuts. And having a peanut allergy doesn't mean that someone will be allergic to tree nuts. But a child is more likely to have a tree nut allergy if they have a peanut allergy.
If my child is allergic to tree nuts, do they also need to avoid seeds?
If your child is allergic to tree nuts, they usually don’t need to avoid seeds. Seeds like sesame seeds, pumpkin seeds, sunflower seeds, mustard seeds and poppyseeds are not tree nuts.
Allergies to these seeds aren’t considered tree nut allergies. If your child does have an allergy to one of these seeds (like sesame), that allergy is different from a tree nut allergy.
Tree nut allergies and other foods
Coconut: The FDA calls coconut a tree nut, but coconuts are really a fruit. Most people with tree nut allergies are able to eat coconut without any issues. Still, please talk to an allergist about any concerns with tree nut allergies and coconut.
Shea nut: Shea is also considered a tree nut, and must be clearly identified as an ingredient on food labels. But like coconut, shea products usually don’t cause problems for people allergic to tree nuts. There are few to no reports of allergic reactions to shea products.
Nutmeg: Even with a name that starts with “nut,” nutmeg doesn’t come from a tree nut. Rather, it comes from a seed. Nutmeg is safe for people with tree nut allergies.
As always, talk to your allergist about any concerns you have about managing tree nuts and avoiding certain foods.
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