In This Chapter
^ Revealing what a food allergy is ^ Finding foods most likely to trigger allergic reactions Discovering whether you're allergic to a specific food ^ Exploring differences between food allergy and food intolerance ccording to the Food Allergy & Anaphylaxis Network (FAAN), at least W »11.4 million Americans have true food allergies (also known as food hypersensitivity); this number includes more children than adults because many childhood allergies seem to fade with age.
So, you may ask, if allergies are likely to disappear, why do I need a whole chapter about them? Good question. I have two good answers. First, food allergies that don't disappear can trigger reactions ranging from the trivial (a stuffy nose the day after you eat the food) to the truly dangerous (immediate respiratory failure). Second, a person with food allergies is likely to be allergic to other things, such as dust, pollen, or the family cat. And forewarned (about food allergies) is forearmed (against the rest), right? Right.
Your immune system is designed to protect your body from harmful invaders, such as bacteria. Sometimes, however, the system responds to substances normally considered harmless. The substance that provokes the attack is called an allergen; the substances that attack the allergen are called antibodies.
A food allergy can provoke such a response as your body releases antibodies to attack specific proteins in food. When this happens, some of the physical reactions include
1 Hives 1 Itching i Swelling of the face, tongue, lips, eyelids, hands, and feet i Rashes i Headaches, migraines i Nausea and/or vomiting i Diarrhea, sometimes bloody i Sneezing, coughing i Asthma
1 Breathing difficulties caused by tightening (swelling) of tissues in the throat i Loss of consciousness (from anaphylactic shock)
If you're sensitive to a specific food, you may not have to eat the food to have the reaction. For example, people sensitive to peanuts may break out in hives just from touching a peanut or peanut butter and may suffer a potentially fatal reaction after simply tasting chocolate that has touched factory machinery that previously touched peanuts. People sensitive to seafood — fin fish and shellfish — have been known to develop breathing problems after simply inhaling the vapors or steam produced by cooking the fish.
Understanding how an allergic reaction occurs
When you eat a food containing a protein to which you're sensitive, your immune system releases antibodies that hitch a ride on white blood cells called basophils. The basophils circulate through your entire body, giving the antibodies the chance to hop off and bind to immune system cells called mast cells.
Basophils and mast cells produce, store, and release histamine, a natural body chemical that causes the symptoms — itching, swelling, hives — associated with allergic reactions. Yes, that's why some allergy pills are called anti-histamines. When the antibodies carried by the basophils and mast cells come in contact with food allergens, boom! You have an allergic reaction.
Investigating two kinds of allergic reactions
Your body may react to an allergen in one of two ways — immediately or later on:
^ Immediate reactions are more dangerous because they involve a fast swelling of tissue, sometimes within seconds after contact with the offending food.
^ Delayed reactions, which may occur as long as 24 to 48 hours after you've been exposed to the offending food, are usually much milder, perhaps a slight cough or nasal congestion caused by swollen tissues.
So you think you have allergies. Now you need to know about the lingo of allergies. These words and definitions (an allergy glossary, if you will) can help you understand what's going on with allergies:
allergen: Any substance that sets off an allergic reaction (see "antigen" in this sidebar)
anaphylaxis: A potentially life-threatening allergic reaction that involves many body systems, creating a cascade of adverse effects beginning with sudden, severe itching and moving on to tissue swelling in the air passages that can lead to breathing difficulties, falling blood pressure, unconsciousness, and death antibody: A protein in your blood that reacts to an antigen by trying to render it harmless antigen: A substance that stimulates a response from the immune system; an allergen is a specific type of antigen basophil: A white blood cell that carries IgE and releases histamine antibodies in your blood, including antibodies to specific allergens histamine: The substance released by the immune system (specifically by basophils and mast cells) that produces the symptoms of an allergic reaction such as itching and swelling intolerance: A nonallergic adverse reaction to food
IgE: An abbreviation for immunoglobulin E, the antibody that reacts to allergens mast cell: A cell in body tissue that releases histamine
RAST: An abbreviation for radioallergosorbent test,a blood test used to determine whether you're allergic to certain foods urticaria: The medical name for hives
American Academy of Allergy & Immunology, International Food Information Council Foundation, "Understanding Food Allergy" (April 1995)
ELISA: Short for enzyme-linked immunosorbent assay, a test used to determine the presence of
Most allergic reactions to food are unpleasant but essentially mild. However, as many as 150 to 200 people die every year in the United States from a severe reaction to a food allergy.
Call 911 immediately if you — or a friend or relative — show any signs of an allergic reaction — including an allergic reaction to food — that affects breathing.
It's all in the family: Inheriting food allergies
A tendency toward allergies (although not the particular allergy itself) is inherited. If one of your parents has a food allergy, your risk of having the same problem is two times higher than if neither of your parents were allergic to foods. If both your mother and your father have food allergies, your risk is four times higher.
Considering Foods Most Likely to Cause Allergic Reactions
Here's something to chew on: More than 90 percent of all allergic reactions to foods are caused by just eight foods (see Figure 23-1):
i Milk i Eggs i Peanuts i Tree nuts i Soybean-based foods i Wheat i Fish 1 Shellfish
These foods can set off an allergic reaction.
These foods can set off an allergic reaction.
Bill it (peanut-free), and they will come
In the real world, having a peanut allergy may affect your ability to enjoy simple pleasures, such as a baseball game where peanuts are sold. So imagine the delight of parents in New Britain, Connecticut, when the local Eastern League team (the Rock Cats) decided to set aside a special 138-seat food-free section during its 2002 season for baseball-crazy but peanut-allergic kids and their families at a game between the Rock Cats and the New Haven Ravens.
The Rock Cats and the Food Allergy & Anaphylaxis Network, a national consumer advocacy group with 250 members in the Hartford area, cooked up the idea because, as Rock Cats assistant general manager John Willi has said, "No child should be deprived of the Rock Cats experience."
Other minor league teams, such as the North Carolina Hickory Crawdads, the West Michigan Whitecaps, and the St. Paul (Minnesota) Saints have all had peanut-free sections for at least one game during the 2001, 2002, 2003, 2004, and 2005 seasons.
But with the exception of the Texas Rangers, who have experimented with a peanut-free section at one game per season, the big leagues are still striking out on this one. Write or e-mail your local clubs to urge them to join the anti-allergy team. Go. Now. Batter up!
Because different people are sensitive to different foods, more than one elimination diet exists. The three listed here eliminate broad groups of foods known to cause allergic reactions in many people. Your doctor will pick the one that seems most useful for you.
Diet No. 1: No beef, pork, poultry, milk, rye, or corn
Diet No. 3: No lamb, poultry, rye, rice, corn, or milk
The Merck Manual, 16th ed. (Rahway, N.J.: Merck Research Laboratories, 1992)
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