Tree Nut Allergy Diet Guide

In the United States, about one in every 200 people have a tree nut allergy, making it one of the most common food allergies amongst both adults and kids.

While most tree nut allergies start in childhood, it is possible develop a tree nut allergy when you are older. Only about 10% of people end up outgrowing their allergy over time.

Tree nuts—almonds, cashews, walnuts, and others—often cause strong allergic reactions. In some cases, these can be life-threatening. People who have an allergy to one type of tree nut often also have allergies to others.

Those allergic may not only need to avoid the nuts and products made with them, but also things prepared or packaged in the same facilities that process them.

This article explains the symptoms of tree nut allergies and how they are diagnosed. It also provides a tree nut list and details many of the foods that may contain tree nuts.

What Is Tree Nut Allergy?

As with other food allergies, a tree nut allergy is caused by the body's immune system reacting to the nut as if it is harmful to the body, even though it's not. Whatever is in a food that is triggers the reaction is known as an allergen.

In those with a tree nut allergy, proteins are the allergens that are to blame. They are essentially viewed by the immune system the same as if they were bacteria or another substance that could threaten your health.

The immune system responds accordingly by mounting a chemical defense. These chemicals, known as antibodies, lead to the release of other substances called histamines. They, in turn, trigger the symptoms of an allergic reaction to tree nuts.

Most people with tree nut allergies will have them for their lifetime.

Symptoms of Tree Nut Allergy

There are many symptoms of a tree nut allergy. Some occur when you consume the nut or something that has even just particles from one. Others can occur simply because you're exposed to the nut by, say, picking one up.

They are likely to vary from person to person, but you will likely experience at least some of the following:

• Itchy skin hives (urticaria)
• Lip swelling (angioedema)
• Oral allergy syndrome (lips, mouth, and throat that itch and burn)
• Contact dermatitis (when your skin is irritated because you've touched a tree nut)
• A tightening throat
• Eyes that itch and water
• Conjunctivitis (pink eye)
• Asthma symptoms that get worse
• Stomach pain
• Diarrhea or vomiting
• Coughing and wheezing

Tree nut allergy symptoms may occur right away or be delayed for up to a day. Many symptoms will resolve on their own, but some people will need medical care. Symptoms can progress quickly and, in some cases, be life-threatening.

Risk Factors of Tree Nut Allergy

There are quite a few reasons why a person may be more at risk of developing a tree nut allergy.

Exposure to environmental factors like air pollution or chemicals may contribute to the likelihood that you'll develop a new allergy. Your genes and family history may play a role in tree nut or other allergies.

There also may be links with other medical conditions. One study of 2,215 young adults in Sweden measured participants' consumption of and sensitivity to tree nuts at ages 12, 16, and 24. It found that 21.2% showed signs of sensitivity to tree nuts overall, with 7.9% experiencing symptoms.

Those who had egg allergies, an eczema skin condition, or asthma at pre-school age were more likely to experience allergic symptoms from tree nuts. By the time they were 24 years old, the presence of a tree nut allergy was associated with both eczema and severe asthma.

Types of Tree Nuts

There are many different types of tree nuts found across the world.

Among the more common tree nuts that you're likely to have eaten are:

• Almonds
• Brazil nuts
• Cashews
• Chestnuts
• Hazelnuts
• Pecans
• Pine nuts
• Pistachios
• Macadamia nuts
• Walnuts

Botany lovers will note that some on this list are not true nuts, according to the scientific definition. However, they are all grouped under the tree nut umbrella because they come from trees. Some can trigger an allergy. (This is perhaps also because most people can't tell a true nut from a lookalike.)

Other tree nuts, used less often, include beechnuts, butternuts, chinquapins, gingko, hickory nuts, lychee nuts, and pili nuts. Shea nuts, which grow on the African shea tree, are not always considered a tree nut but—as with coconuts—the FDA requires manufacturers to label them as such.

A Word About Peanuts

Peanuts are grown in the ground and are legumes, which are unrelated to tree nuts.

A tree nut allergy does not mean you automatically have a peanut allergy. However, it is possible to have both of these distinct conditions. About 40% of kids who are allergic to tree nuts also react to peanuts.

Even if you're not allergic to peanuts, they can still pose a problem if you have tree nut allergies because of their high risk for cross-contamination. Tree nut proteins may find their way onto peanuts because they are processed in the same manufacturing plant. These nuts are also often mixed together in food products.

Because of the risk of allergic reaction, people with tree nut allergies should avoid products that mention the possibility of tree nut cross-contamination on labels.

Allergies to More Than One Tree Nut

If you are allergic to one tree nut, it does not mean you're allergic to all of them. In fact, most people aren't.

However, reactions to more than one type of tree nut are not uncommon. Australian researchers have found that 30% of children ages 10 to 14 who have an allergy to one tree nut also have an allergy to at least one more.

This is because tree nuts can contain similar problematic proteins. This is true of almonds and hazelnuts, walnuts and pecans, as well as pistachios and cashews.

Children who are allergic to more than one or two tree nuts are less likely to outgrow their allergies. For this reason, healthcare providers recommend that children with tree nut allergies be periodically reassessed to see if or how a tree nut allergy has changed over time.

Foods Made With Tree Nuts

Tree nuts are used in a variety of foods—some obvious, some perhaps not.

For example, milks like almond milk and main dishes like chicken with cashew sauce very clearly contain tree nuts.

But tree nuts are also often ingredients in baked goods, ice cream, cereals, sauces, and other manufactured products. You might only know they are there after reading the food label or asking the baker.

Some of the foods that always (or almost always) have tree nuts as ingredients include:

• Nutella, made with hazelnuts
• Marzipan, an almond paste
• Baklava (a layered pastry filled with chopped nuts)
• Pralines
• Nut liqueurs, including Frangelico, Amaretto, and Nocello
• Nougat candies
• Turrón, a candy typically made with almonds
• Gianduja, a creamy chocolate mixed with almonds, hazelnuts, and sometimes other nuts
• Almond and other nut flours
• Wintergreen and other nut extracts

There are many other foods that may contain tree nuts. They may include:

• Macaroons
• Granola bars
• Trail mix
• Energy bars
• Flavored coffee
• Frozen desserts
• Cereal
• Marinades
• Caponata (pine nut dish)
• Barbecue sauces
• Ice cream
• Mortadella (lunchmeat)
• Candy bars
• Baked goods
• Crackers
• Cookies

As with many common allergens, tree nuts are sometimes found in unlikely foods. This list does not include them all, so be sure to read labels on all packaged foods before buying or eating them.

How Tree Nut Allergies Are Diagnosed

A healthcare provider can diagnose a tree nut allergy based on factors like the kinds of symptoms you have, when they occurred, and how severe they are. It's likely that you'll want to see a board-certified allergist who specializes in food allergies.

They'll use this and other information, such as your family history and any other medical conditions you have, to begin an evaluation for tree nut allergy.

You may be asked to keep a food diary to record what you've been eating and what kinds of symptoms may follow.

You also may be asked to try an elimination diet, and remove tree nuts for two weeks. You'll watch for changes in your symptoms to identify if the tree nut is the cause, and then add them back into your diet to see if your symptoms return.

Skin prick tests can help an allergist come to a diagnosis. This is when tree nut proteins are purposefully introduced to your skin to see if a reaction occurs.

Blood tests also may be used to confirm a tree nut or other food allergy.

Eating Out With Tree Nut Allergies

There are some places where it may be difficult to avoid tree nuts. For example, you may attend parties or gatherings where bowls of mixed nuts may be served or you're not sure how foods were prepared.

In restaurants, it's easy to find out what dishes contain tree nuts and don't. Don't rely on the menu; ask about the ingredients in whatever you'd like to order.

Cuisines that may use nuts include:

• Greek (walnuts)
• Chinese (cashews)
• Mediterranean (almonds)
• Italian (pine nuts)

Restaurants also may use tree nut oils to make marinades and salad dressings. 

That said, the risk of a dangerous allergic reaction is still there. For example, foods containing tree nuts may be prepared on the same surface as the nut-free dish you order. Make sure your server is aware of your tree nut allergy so this can be avoided.

Tree Nuts and Food Labeling Laws

The Food Allergy Labeling and Consumer Protection Act (FALCPA) of 2004 was proposed and passed by the United States Congress because of the prominence of food allergies in the United States and the need for consumers to be able to reliably identify foods that they need to avoid.

It requires manufacturers to label packaged food products containing tree nuts—and to note what specific nuts they contain—when they are sold in the U.S. The law also applies to other key food allergens, such as milk, wheat, and soy. FALCPA is enforced by the FDA.

The law does not require that the labeling language be the same on every product, or that the messaging be placed in a specific location on the label. So, while you may find a prominent "tree nut-free" icon on the front of one product, another may have a simple line of text somewhere under the nutritional facts.

Although FALCPA also does not require manufacturers to report if a food is made on a production line that also processes tree nuts or products that contain them, many companies do voluntarily.

Whether the law will be amended to address these things is to be seen. However, it's possible that manufacturers may not wait given the strong and growing consumer demand for clearer, more consistent food allergen labeling.

Summary

Tree nuts are one of the top causes of food allergy. They evoke an immune system response that leads to symptoms of allergic reaction in some people, including a tightening throat, lip swelling, and hives.

Symptoms can get to the point where they are severe enough to cause anaphylaxis, a body-wide, life-threatening reaction. Use your epinephrine injector and call 911 right away.

There are a number of possible factors that raise the risk for tree nut allergies, including family history. In many cases, tree nut allergies will last a lifetime. You'll need to know how to avoid the tree nuts that cause your allergic reactions and read product labels carefully.

A Word From Verywell

Keep in mind that if your child has a tree nut allergy, teachers and other adults in their life will need to know. You'll want to be sure your child knows how to avoid tree nuts too.

For adults, be sure that someone knows where you keep your epinephrine injector so they can help you if needed.