Food Hypersensitivity

According to the Food Allergy & Anaphylaxis Network (FAAN), at least 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 write 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.

Finding Out More about 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 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.

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 antihistamines. 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.

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.

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.

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:

  • Milk
  • Eggs
  • Peanuts
  • Tree nuts
  • Soybean-based foods
  • Wheat
  • Fish
  • Shellfish

Identifying Food Allergies

To identify the culprit causing your food allergy, your doctor may suggest an elimination diet. This regimen removes from your diet foods 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.

Two more-sophisticated tests — ELISA (enzyme-linked immunosorbent assay) and RAST (radioallergosorbent test) — can identify antibodies to specific allergens in your blood. But these two tests are rarely required.

Coping with Food Allergies

After you know that you’re allergic to a food, the best way to avoid an allergic reaction is to avoid the food. Unfortunately, that task may be harder than it sounds because the offending ingredient may be hidden — peanuts in the chili or caviar (“fish eggs”) in the dip.

Sometimes the “hidden” ingredient is hidden in plain sight on a food label that uses chemical code names for allergens. Example? How about “whey” or “casein” or “lactoglobulin” for “milk.” Happily, in the summer of 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. Goodbye “whey,” “casein,” and “lactoglobulin.” Hello, milk. About time, I say.

If you’re someone with a 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, a drug that counteracts the reactions.

You may also want 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 (in the U.S.) and 209-668-3333 (from outside the U.S.)

The food industry takes food allergies so seriously that the National Restaurant Association has joined forces with the American Academy of Allergy, Asthma, & Immunology; the Food Allergy & Anaphylaxis Network; and the International Food Information Council Foundation (IFIC) to produce a poster that shows allergenic foods and gives directions on how to assist in an allergy emergency.

The poster is made to be hung in restaurant kitchens. For your very own $2.50 copy, go to the IFIC home page, type “allergy poster” in the Search box, click on Food Allergy Poster for Food Service Workers, and follow the prompts. You may want to visit the following Web sites for more details on food allergies:

Recognizing Other Body Reactions to Food

Allergic reactions aren’t the only way your body registers a protest against certain foods. Food intolerance is a term used to describe reactions that are common, natural, and definitely not allergic, which means that these reactions do not involve production of antibodies by the immune system. Some common food intolerance reactions are:

  • A metabolic food reaction: This response is an inability to digest certain foods, such as fat or lactose (the naturally occurring sugar in milk). Metabolic food reactions can produce gas, diarrhea, or other signs of gastric revolt and are an inherited trait.
  • 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 that 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 hyperdrive, 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 have a real effect on mood and behavior. Turn the page, and it’s yours.