Nut and Peanut Allergy

Sun Jan 30, 2005

KidsHealth.org

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 separate table with other children who have food allergies. But Justin isn't alone: The U.S. Food and Drug Administration estimates that 6% of children younger than 3 years old have some kind of allergy to food, putting them at risk of an allergic reaction at home, or even more dangerously, away from home.

It seems ironic that one of the most popular, most readily available proteins causes one of the most pervasive and severe allergies among Americans.

What Are Nut and Peanut Allergies?
The most common allergy-causing foods are peanuts, tree nuts, milk, eggs, fish, shellfish, wheat, and soy, according to the Food Allergy and Anaphylaxis Network (FAAN). About 1.5 million people in the United States are allergic to peanuts (which are not a true nut, but a legume - in the same family as peas and lentils). Half of those allergic to peanuts are also allergic to tree nuts, such as almonds, walnuts, pecans, cashews, and often sunflower and sesame seeds. The American Academy of Allergy, Asthma, and Immunology estimates that up to 2 million, or 8%, of children in the United States are affected by food allergies, and that six foods account for 90% of those food allergy reactions in kids: milk, eggs, peanuts, wheat, soy, and tree nuts.

Food allergies occur when a person's immune system mistakenly believes that something he or she ate is harmful to the body. In an attempt to protect the body, the immune system produces antibodies called immunoglobulin E (IgE). Those antibodies then cause mast cells (which are allergy cells in the body) 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. Future exposure to that same allergen (things like nuts or pollen that you can be allergic to are known as allergens) will trigger this antibody response again. This means that every time that person eats that particular food, he or she will have an allergic reaction.

Unlike allergies to other foods like milk and eggs, children generally don't outgrow allergies to peanuts or nuts. But over time, they should become experienced at avoiding the foods that make them ill.

Signs and Symptoms
The first signs of an allergic reaction can be a runny nose, a skin rash all over the body, or a tingly tongue. The symptoms can quickly become more serious - including signs of anaphylaxis (a sudden, potentially severe allergic reaction involving various systems in the body), such as difficulty breathing, swelling of the throat or other parts of the body, a rapid drop in blood pressure, and dizziness or unconsciousness. Other possible symptoms include hives, tightness of the throat, a hoarse voice, nausea, vomiting, abdominal pain, diarrhea, and lightheadedness. To someone who has no allergies, seeing someone else experiencing anaphylaxis can be just as scary as it is for the allergic person. Anaphylaxis can happen just seconds after being exposed to a triggering substance. It can involve various areas of the body (such as the skin, respiratory tract, gastrointestinal tract, and cardiovascular system), and can be mild to fatal. The annual incidence of anaphylactic reactions is small - about 30 per 100,000 people - although people with asthma, eczema, or hay fever are at greater risk of experiencing them.

How Is a Nut or Peanut Allergy Diagnosed?
Obviously, babies can't tell their parents when their tummies hurt or their throats itch, so diagnosing food allergies early in a child's life can be difficult. Doctors therefore generally recommend that parents refrain from giving their children peanut butter or other peanut or nut products until after they're 2 years old. If there's a family history of food allergies, parents should wait until the child is 3. And many doctors recommend that their pregnant patients - especially those with food allergies - keep the lid on the peanut butter jar until after the baby's born and they're done nursing.

If your doctor suspects your child might have a peanut or nut allergy, he or she will probably refer you to an allergist or allergy specialist for further testing. The allergy specialist will ask you and your child questions, such as how often does your child have the reaction, how quickly do symptoms start after eating a particular food, and whether any family members have allergies or conditions like eczema and asthma.

Allergies are diagnosed using a skin test or blood test, depending on the age and condition of the patient. Initially, the suspected allergen is placed on the skin and the skin is pricked with a plastic toothpick-like instrument. If the child is allergic, a reaction (a welt that looks like a mosquito bite) will develop in 20 minutes. Skin testing can also be done by injecting the suspected allergen under the skin with a needle.

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