Nut and Peanut Allergy
Peanuts are among the most common allergy-causing foods, and they often find their way into things you wouldn't imagine. Take chili, for example: It may be thickened with ground peanuts.
Peanuts aren't actually a true nut; they're a legume (in the same family as peas and lentils). But the proteins in peanuts are similar in structure to those in tree nuts. For this reason, people who are allergic to peanuts can also be allergic to tree nuts, such as almonds, Brazil nuts, walnuts, hazelnuts, macadamias, pistachios, pecans, and cashews.
What Happens With a Nut or Peanut Allergy?
An allergic reaction happens when someone's immune system mistakenly believes that something harmless, such as a tree nut or peanut, is actually harmful. The immune system responds by creating specific antibodies to proteins in that food. These antibodies — called immunoglobulin E (IgE) — are designed to fight off the "invading" proteins.
IgE antibodies trigger the release of certain chemicals into the body. One of these is histamine (pronounced: hiss-tuh-meen). The release of histamine can affect a person's respiratory system, gastrointestinal tract, skin, and cardiovascular system, causing allergy symptoms like wheezing, stomachache, vomiting, itchy hives, and swelling.
Reactions to foods, like peanuts and tree nuts, can be different. It all depends on the person — and sometimes the same person can react differently at different times. Some reactions can be very mild and involve only one system of the body, like hives on the skin. Other reactions can be more severe and involve more than one part of the body. Most reactions last less than a day and affect any of these four body systems:
- Skin. Skin reactions are the most common type of food allergy reactions. They can take the form of itchy, red, bumpy rashes (hives), eczema, or redness and swelling around the mouth or face.
- Gastrointestinal system. Symptoms can take the form of belly cramps, nausea, vomiting, or diarrhea.
- Respiratory system. Symptoms can range from a runny or stuffy nose, itchy, watery eyes, and sneezing to the triggering of asthma with coughing and wheezing.
- Cardiovascular system. A person may feel lightheaded or faint and lose consciousness.
In really bad cases, tree nut and peanut allergies can cause a condition called anaphylaxis (pronounced: ah-nuh-fuh-lak-sus). Anaphylaxis is a sudden, potentially life-threatening reaction that, in addition to the symptoms mentioned above, can make someone's airways swell and blood pressure drop. As a result, the person may have trouble breathing and could lose consciousness.
Peanut reactions can be very severe, even if a person isn't exposed to much peanut protein. Experts think this might be because the immune system recognizes peanut proteins more easily than other food proteins.
Although a small amount of peanut protein can set off a severe reaction, it is rare that people get an allergic reaction just from breathing in small particles of nuts or peanuts. Most foods with peanuts in them don't allow enough of the protein to escape into the air to cause a reaction. And just the smell of foods containing peanuts won't produce a reaction because the scent does not contain the protein.
In the few cases when people do react to airborne particles, it's usually in an enclosed area (like a restaurant or bar) where lots of peanuts are being cracked from their shells. Although some people outgrow certain food allergies over time (like milk, egg, soy, and wheat allergies), peanut and tree nut allergies are lifelong in most people.
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