First grade has been a difficult parenting year for Anne. Her 6-year-old son, Justin, began eating lunch in the cafeteria with hundreds of other students armed with their peanut butter sandwiches, peanut butter crackers, and all those hidden peanuts in their processed foods.

For Justin, who has an extremely severe allergy to peanuts, it means sitting at a peanut-free table. But Justin isn't alone: The U.S. Food and Drug Administration (FDA) estimates that 6% of children younger than 3 years old have some kind of food allergy, putting them at risk of an allergic reaction at home or, even more dangerously, away from home.

What Are Peanut and Tree Nut Allergies?

Peanuts are among the most common allergy-causing foods. But because a peanut allergy is less likely to be outgrown than allergies to other foods, it becomes more common among older kids and adults. It's likely that more Americans are allergic to peanuts than any other food.

Peanuts are actually not a true nut, but a legume (in the same family as peas and lentils). When someone with a peanut allergy is exposed to peanuts, the immune system mistakenly believes that proteins (or allergens) in the peanut are harmful to the body.

The immune system produces antibodies called immunoglobulin E (IgE) that then cause allergy cells in the body (called mast cells) to release chemicals into the bloodstream, one of which is histamine. The histamine then acts on a person's eyes, nose, throat, lungs, skin, or gastrointestinal tract, and causes the symptoms of the allergic reaction.

Peanut reactions can be very severe, even with extremely small amounts of exposure. This might be because the immune system recognizes peanut proteins easier than other food proteins.

The allergens in peanuts are similar in structure to allergens in tree nuts. This may explain why almost half of people who are allergic to peanuts are also allergic to tree nuts, such as almonds, Brazil nuts, walnuts, hazelnuts, macadamias, pistachios, pecans, and cashews.

People who are allergic to one tree nut are often allergic to at least one or two other tree nuts. As with peanuts, tree nut reactions can be very severe, even with small exposures. Research has shown that peanuts are the #1 culprit of fatal food allergy reactions, followed by tree nuts.

Living With a Peanut or Tree Nut Allergy

To help reduce contact with nut allergens and the possibility of severe reactions (anaphylaxis) in someone with a peanut or tree nut allergy:

• Consider making your entire home nut-free.
• If you do allow nuts in your home, watch for cross-contamination that can happen with utensils and cookware. For example, make sure the knife you use to make peanut butter sandwiches is not used in preparing food for a child with a nut allergy, and that nut breads are not toasted in the same toaster as other breads.
• Don't serve cooked foods you didn't make yourself, or anything with an unknown list of ingredients.
• Tell everyone who handles the food your child eats, from waiters and waitresses to the cafeteria staff at school, about the allergy. If the manager or owner of a restaurant is uncomfortable about your request for peanut- or nut-free food preparation, don't eat there.
• Consider making your child's school lunches, as well as snacks and treats to take to parties, play dates, sleepovers, school functions, and other outings.
• Talk to the daycare supervisor or school principal before your child attends. Work together to create a food allergy emergency action plan.
• Keep epinephrine accessible at all times — not in the glove compartment of your car, but with you, because seconds count during an anaphylaxis episode.

With a little preparation, and prevention, you can ensure that your child's allergy doesn't get in the way of a happy, healthy, everyday life.

Reviewed by: Hemant P. Sharma, MD
Date reviewed: April 2008