Chapter 23

When Food Gives You Hives

IN THIS CHAPTER

Describing food allergies

Identifying the foods that trigger allergies

Exploring differences between food allergy and other food reactions

According to the Food and Drug Administration (FDA), at least 2 percent of all American adults and 5 percent of infants and young children have a true food allergy (also known as food hypersensitivity).

This number includes more children than adults because many childhood allergies seem to fade with age. But 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). And a person with food allergies is likely to be allergic to other things, such as dust, pollen, or the family cat. So forewarned (about food allergies) is forearmed (against the rest).

A word to the allergy-wise: You can stay current with allergy news by checking out the American Academy of Allergy, Asthma & Immunology (www.aaaai.org) and the Food Allergy & Anaphylaxis Network (www.foodallergy.org).

Diagnosing Food Allergies

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

• Hives
• Itching
• Swelling of the face, tongue, lips, eyelids, hands, and feet
• Rashes
• Headaches, migraines
• Nausea and/or vomiting
• Diarrhea, sometimes bloody
• Sneezing, coughing
• Asthma
• Breathing difficulties caused by tightening (swelling) of tissues in the throat
• 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 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, the protein reaches antibodies on the surface of white blood cells called basophils and immune system cells called mast cells either in your gastrointestinal tract or by circulating through the bloodstream.

ALLERGY GLOSSARY

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 and tries 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.

ELISA: Short for enzyme-linked immunosorbent assay, a test used to determine the presence of antibodies in your blood, including antibodies to specific allergens.

epinephrine: Also known as adrenaline, β,3,4-trihydroxy-N- methylphenethylamine, a naturally occurring hormone used as medicine to treat severe allergic reactions.

histamine: The substance released by the immune system (specifically by the white blood cells known as basophils and by basophil-filled mast cells) that produces the symptoms of an allergic reaction, such as itching and swelling.

IgE: An abbreviation for immunoglobulin E, the antibody that reacts to allergens.

intolerance: A non-allergic adverse reaction to food.

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.

The basophils and mast cells produce, store, and release histamine, a natural body chemical that causes the symptoms — itching, swelling, hives — associated with allergic reactions (some allergy pills designed to counter this are called antihistamines). When the antibodies on the surface of the basophils and mast cells come in contact with food allergens, the cells release histamine, and the result is 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.

Most allergic reactions to food are unpleasant but essentially mild. However, as many as 150 or more people die every year in the United States from a severe reaction to a food allergen.

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.

Identifying food allergies

A tendency toward allergies (although not necessarily the specific allergy itself) is inherited. If one of your parents has an allergy, your risk of having one is two times higher than it would be if neither of your parents had a history of allergic disease. If both your mother and your father have allergies, your risk is four times higher.

To identify the culprit causing your food allergy, your doctor may suggest an elimination diet. This regimen removes from your diet foods — most commonly milk, egg, soy, wheat, peanuts — known to cause allergic reactions in many people. Then, one at a time, the foods are added back. If you react to one, bingo! That’s a clue to what triggers your immune response.

To be absolutely certain, your doctor may challenge your immune system by introducing foods in a form (maybe a capsule) that neither you nor he can identify as a specific food. Doing so rules out any possibility that your reaction has been triggered by emotional stimuli — that is, seeing, tasting, or smelling the food.

Other tests that can identify allergens to specific foods include skin tests and two types of blood tests — ELISA (enzyme-linked immunosorbent assay) and RAST (radioallergosorbent test) — that can identify antibodies to specific allergens in your blood. But these two tests are rarely required.

Coping with Food Allergies

To keep yourself or your allergic friends and family safe in a world practically teeming with allergens, know what’s in your food, check out unusual allergenic couplings, work with others to make rules that work, and practice simple protection.

Reading the food ingredient label

According to the Food Allergy and Anaphylaxis Network, more than 90 percent of all allergic reactions to foods are caused by just eight foods: eggs, fish, milk, peanuts, shellfish, soy, tree nuts, and wheat.

If you’re sensitive to one of these foods, the best way to avoid an allergic reaction is to avoid the food. And you can do that by reading the label to ferret out hidden ingredients — peanuts in the chili or caviar (fish eggs) in the dip.

In the past, a hidden allergen might be hidden in plain sight on a food label that used alternative or chemical code names, such as whey or casein or lactoglobulin for milk. But in 2004, Congress passed and the president signed into law the Food Allergen Labeling and Consumer Protection Act. As of January 1, 2006, all food labels must use plain English words for the eight most-common food allergens.

Table 23-1 lists and describes The Allergy Eight, with special attention to those unexpected appearances on the menu (also see Figure 23-1).

Table 23-1 The Allergy Eight

Food	People Affected1	Where This Food May Hide in Commercial Products
Eggs	1–2% of young children; most outgrow this allergy	Foam/topping on coffee drinks; egg substitutes; pasta in prepared foods (like soups); pretzels/bread (egg wash on crust)
Fish	2.3% of all Americans (children and adults)	Dressings and sauces (Worcestershire sauce); Asian and Mexican dishes; prepared meat products (like meatloaf)
Milk	2.3% of children under 3; most outgrow this allergy	Canned tuna, meat, and nondairy products (as casein, the protein in milk)
Peanuts2	1% of American children and adults; recent studies suggest that up to 20% of allergic children may outgrow this allergy	Dressings and sauces; marinades; pizza; Asian and Mexican dishes; meat substitutes
Shellfish	2.3% of all Americans	Sauces (like fish sauce); Asian dishes
Soy	NA3; many children outgrow this allergy	Baked products including cereals and snacks; margarines; meat substitutes (textured vegetable protein); nut butters; sauces; prepared soups
Tree nuts4	0.5% of American children and adults	Salad dressings; sauces (barbecue sauce); breaded foods; meat substitutes (vegetarian burgers); pastas
Wheat5	>1% of children younger than 3; most outgrow this allergy	Various foods including ice cream; chips; meat, fish, and poultry products (prepared burgers, hot dogs, imitation crab meat [surimi])

(1) Estimates.

(2) Peanuts, sometimes known as ground nuts, are legumes, a vegetable class that includes peas and beans.

(3) Depending on the source, estimates range from a low of 0.3% of young children to a high of 20% of all children and adults.

(4) Including, among others, almonds, Brazil nuts, cashews, chestnuts, coconuts, hazelnuts, Macadamia nuts, pecans, pistachios, walnuts.

(5) Wheat allergy has no relationship with celiac disease, a genetic malabsorption disorder in which the body reacts to gluten, a protein in some grains (primarily wheat, barley, oats, and rye). Celiac disease is a lifelong condition. About.com, http://foodallergies.about.com/od/soyallergies/p/soyallergy.htm, Food Allergy and Anaphylaxis Network, www.foodallergy.org; Mayo Clinic, www.mayoclinic.com/health/soy-allergy/DS00970; “Is Soy Allergy Overestimated?” Luisa Businco. Pediatric Asthma, Allergy & Immunology, Summer 1993, 7(2): 73-76

© John Wiley & Sons, Inc.

FIGURE 23-1: These foods can set off an allergic reaction.

Avoiding unusual interactions

Sometimes a food label doesn’t list an allergen because the allergen is simply (surprise!) a natural component of the food.

Salicylates are a perfect example. These natural chemicals occur in many plants, including some plants that end up on the dinner table. The salicylates protect the plants by destroying mold and other microorganisms. For human beings, salicylates act as analgesics (pain killers), the most famous of which is acetylsalicylic acid, better known as aspirin. People who are sensitive to salicylates may experience an allergic reaction (wheezing and difficulty breathing, headache, hives, rash or itchy skin, and swollen hands, feet, or face) when exposed even to very small amounts, including the salicylates in otherwise highly nutritious plant foods such as fruits and vegetables.

If you or someone you know is sensitive to salicylates, you’ll be pleased to know that the allergy experts at the Wegeningen University in the Netherlands have put together a nifty little list of foods grouped into five categories according to the amount of salicylates they contain. The following list, adapted from the Wegeningen chart shown at http://www.food-info.net/uk/qa/qa-fi27.htm, is a basic guide to the salicylate content of common foods. For comparison, one regular aspirin contains 365 milligrams of acetylsalicylic acid; one low-dose aspirin, the medicine prescribed to reduce the risk of heart disease, has 81 milligrams.

• Foods with negligible amounts of salicylates: Bananas, cabbage, cashews, celery, chives, garlic, green beans, pears, peas, and lentils
• Foods low in salicylates (0.1–0.25 milligrams per 3.5 ounces/100 grams): Apples (golden, delicious [red]), asparagus (fresh), cauliflower, cherries (sour), grapes (green), hazel nuts, lemon, mango, mushrooms (fresh), onions, passion fruit, pecans, peanut butter, tamarillo, saffron, sesame seeds, soy sauce, and vinegar
• Foods moderate in salicylates (0.25–0.49 milligrams per 3.5 ounces/100 grams): Asparagus (canned), Brazil nuts, Chinese vegetables, coconut, fennel, grapefruit juice, loquat, lychee, marrow (the British/European term for zucchini), nectarines, olives (black), plum, pumpkin, snow peas, and watermelon
• Foods high in salicylates (0.5–1.0 milligrams per 3.5 ounces/100 grams): Alfalfa, apples (Granny Smith), avocado, broccoli, cherries (red), cucumber, fava beans, Macadamia nuts, mandarin oranges, pine nuts, pistachios, spinach, sweet potato, tangelo (tangerine/grapefruit or honeybell), and vegemite (a salty food paste made from yeast)
• Foods very high in salicylates (>1 milligram per 3.5 ounces/100 grams): Almonds, apricots, blackberries, blueberries, canella (a cinnamonlike seasoning), cantaloupe, chicory, cumin, curry powder, dates, dill (dried), green pepper, guava, mushrooms (canned), mustard, olive, oregano, paprika (hot), peanuts, radishes, raisins, rosemary, thyme, tomatoes, and turmeric

WORKING TO CHANGE AN ALLERGENIC ENVIRONMENT

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 formerly known as the Rock Cats and now to be named the Hartford Yard Goats when they move to the capital city, 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 team and the Food Allergy & Anaphylaxis Network, a national consumer advocacy group with 250 members in the Hartford area, cooked up the idea because, as then general manager John Willi said, “No child should be deprived of the Rock Cats experience.”

By 2010, the peanut-free theme had moved well into the majors, with more than one-third of the major-league baseball teams designating games with peanut-free areas. But as Robert Wood, MD, director of pediatric allergy and immunology at the Johns Hopkins Children's Center in Baltimore, author of Food Allergies For Dummies (Wiley), and a person with a peanut allergy himself, has noted, watching a game in an outdoor ballpark is less hazardous than, say, sitting in the cabin in an airplane where the air carries peanut particles and scattered crumbs on the floor or seats. Funny he should mention that. As long ago as 1998, the U.S. Department of Transportation (DOT) considered imposing a ban on peanuts on U.S. carriers only to be stymied by representatives from peanut-growing states. The DOT’s proposals included the following options:

• An outright ban on airlines serving peanuts and peanut products
• Banning service of peanuts and peanut products only on a flight where a passenger with a peanut allergy requests a peanut-free flight in advance
• Requiring the airline to provide a peanut-free buffer zone around a passenger with a medically documented severe peanut allergy if the passenger makes a request in advance

While you’re waiting to see whether these proposals ever fly, remember to check with the airline when making reservations. Some carriers, such as Swiss Air, have already chosen to pilot peanut-free planes.

Practicing pragmatic protection

If you’re someone with a known potentially life-threatening allergy to food (or another allergen, such as wasp venom), your doctor may suggest that you carry a syringe prefilled with epinephrine, the naturally occurring hormone that counteracts the reactions.

You may also decide to wear a tag that identifies you as a person with a serious allergic problem. One company that provides these tags is Medic-Alert Foundation International, a 40+-year-old firm located in Turlock, California. The 24/7 telephone number for Medic-Alert is 888-633-4298; the 24/7 Hotline is 800-432-5378. The website is www.medicalert.org.

Recognizing Other Body Reactions to Food

Allergic reactions aren’t the only way your body registers a protest against certain foods. Other reactions to foods include

• A metabolic reaction: Food intolerance, also known as a non-allergic food hypersensitivity, is an inherited inability to metabolize (digest) certain foods, such as fat or lactose (the naturally occurring sugar in milk). The reaction may include intestinal gas, diarrhea, or other signs of gastric revolt.
• A physical reaction to a specific chemical: Your body may react to things such as the laxative substance in prunes or monosodium glutamate (MSG), the flavor enhancer commonly found in Asian food. Although some people are more sensitive than others to these chemicals, their reaction is a physical one. It doesn’t involve the immune system.
• A body response to psychological triggers: When you’re very fearful or very anxious or very excited, your body moves into hyper drive, secreting hormones that pump up your heartbeat and respiration, speed the passage of food through your gut, and cause you to empty your bowels and bladder. The entire process, called the fight-or-flight response, prepares your body to defend itself by either fighting or running. On a more prosaic level, a strong reaction to your food may cause diarrhea. It isn’t an allergy; it’s your hormones.
• A change in mood and/or behavior. Some foods, such as coffee, contain chemicals, such as caffeine, that may cause hyperactivity, as well as having a real effect on mood and behavior, the subject of Chapter 24.