Food Allergy

Hold the Milk, Eggs, Wheat, and Soy

Standing before an expansive buffet, it's hard to resist the pasta with baby shrimp, a few bite-size quiches, and the homemade breads. You load up your plate, then return for more. This time you stop at the ice cream-sundae bar that is complete with toppings of whipped cream and nuts.

An hour later, with an empty plate and full stomach, you notice red welts forming on your arms. Your skin itches and tingles, you have a slight headache, and your heart is racing. You're also wheezing.

Did you eat too much or are you allergic to something you ate?

Approximately two percent of adults and between three to eight percent of children have some type of food allergy. With some exceptions, most children outgrow their food allergies by the age of 5 or 6. According to the Food Allergy Network, the following eight foods account for 90% of all food allergies: peanuts, tree nuts (e.g., pecans), fish, shellfish, eggs, milk, wheat, soy. There were a number of allergy-causing culprits in that delicious buffet!

What Is a Food Allergy?
A food allergy occurs when specialized cells of the immune system believe an ordinary food to be harmful—an allergen —something that causes an allergic reaction. These cells create immunoglobulin E (IgE) antibodies to combat the allergen. Allergens are usually protein molecules, and the body's antibodies, also protein molecules, are capable of neutralizing allergens.

When the allergen is next ingested, the body releases powerful chemicals called histamines and other chemicals called mediators to protect the body. The body reacts to the histamines with an inflammatory reaction. Typically, the reaction occurs up to two hours after ingestion, however some reactions happen within minutes.

Inflammation may occur almost anywhere in the body: on the skin, in the respiratory or cardiovascular systems, or in the gastrointestinal tract. Symptoms may include a rash, runny or congested nose, sneezing, headache, rapid heart beat, or stomach cramps and bloating. In rare cases, a severe reaction involving all of the body's systems causes a significant drop in blood pressure that may lead to loss of consciousness. This is called anaphylactic shock. Anaphylaxis requires immediate medical treatment.

Read the article "Food Allergies, Rare but Risky" from the FDA Consumer that appeared on the WebMD site.

The AAAAI's article "Tips to Remember: Food Allergy" provides a general overview of allergy symptoms, diagnosis, and treatment.
The Biology Gateways activity, The Mechanism of Breathing examines a healthy respiratory system. The activity Health and the Respiratory System: Asthma explores a respiratory system compromised by the effects of asthma. (These activities require Logal Express. Get a free trial subscription now.)

Almost, but Not Quite

A food intolerance, commonly confused with a food allergy, does not involve the immune system. Symptoms such as stomachaches, headaches, fatigue, and wheezing may occur, but no IgE is produced.
One of the most common intolerances is to lactose, the sugar found in milk. Some individuals, who lack the enzyme to break down the sugar and digest the food, may experience abdominal pain or cramping after eating dairy products.
Sometimes adverse reactions are caused by chemicals or common food additives such as caffeine, aspartame, monosodium glutamate (MSG), or sulfites (added to foods to enhance crispness). According to the American Academy of Allergy, Asthma and Immunology (AAAAI), "true allergic reactions to food additives are very rare." However, some individuals suffer symptoms such as headaches, stomach pain or cramps, and nervousness.

Because sulfites were discovered to trigger asthma attacks, the Food and Drug Administration (FDA) banned them as a spray-on additive. Sulfites occur naturally in wine and are found in some foods.
Cross-reactivity refers to the susceptibility of individuals with allergies to one food being allergic to other foods within the same family. In some cases the connection is obvious. Someone allergic to walnuts might be advised to avoid pecans as well. But on occasion the link is a little more distant, such as the relationship between ragweed sensitivities and the inability to eat cantaloupe!

A Difficult Diagnosis
In order to properly diagnose a food allergy, an individual must work with a qualified health care provider to determine the allergen and the most effective treatment method. An individual might be asked to:

Describe the symptoms: This type of discussion usually serves as a way of understanding the situation, looking for patterns in the reactions, and ruling out other causes.

Keep a daily food diary: Entries detail foods eaten, when and in what quantity, and noticeable reactions.

Go on an elimination diet: The suspected food is completely eliminated from the diet until the symptoms disappear. The food is then gradually reintroduced to see if a reaction occurs. This diet lasts anywhere from several weeks to a few months and may be repeated if numerous foods are suspected.

Participate in a provocation diet: The patient is exposed to the suspected allergen in a controlled setting called a "double-blind placebo-controlled" test. This test must be performed under the supervision of a physician or allergist. The allergen is placed inside a capsule and given to the patient under supervised conditions. The patient is also given capsules that do not contain the allergen ("placebos"). Neither the physician nor the patient are aware of which capsules contain the allergen.

Undergo blood tests: A radioallergosorbent (RAST) test, a blood test done in a laboratory, detects the presence of IgE antibodies. There are other blood tests such as a serum globulin electrophoresis (IEP) used to determine the presence of certain proteins in the blood.

A New Danger
A genetically modified (GM) food is one that has had its DNA modified, usually by introducing the genetic coding from another organism. About half of the nation's soybean crop and roughly a quarter of the corn crop are genetically modified. Some foods, such as corn, have been modified to resist certain insects, and others, such as potatoes, have been engineered to resist viruses.

Traveling Incognito

Most professionals agree that reading food labels is an important step in managing a food allergy. But searching for hidden allergens on a label almost requires a degree in biochemistry:

Shampoos and cosmetics, pastas, and bakery goods may all contain eggs or products derived from eggs. Some common names for egg-related products: albumin, ovomucin, vitellin, phosvitin, ovalbumin, ovomucoic. Lecithin, emulsifiers, and coagulants could also be produced with eggs.
Milk and other dairy products are found in foods from baked goods to meats at the deli counter. Be alert to casein, whey, or lactalbumin on a food label. Some preservatives are also known to contain milk or milk products.

Numerous baked and packaged goods contain soy or soy products. MSG, hydrolyzed vegetable protein, and glycine max are soy-based. Vitamin E, lecithin, and even some natural flavorings are made or derived from soy.

The FDA requires a complete listing of all the ingredients of a food, however manufacturers are allowed to group certain spices, flavorings, and colorings. They also do not need to list "processing aids." While the FDA rethinks its requirements on food labels, some manufacturers have voluntarily added the words "may contain..." along with the name of the allergen to their labels.

Some food allergy sufferers are concerned that GM foods may introduce new allergens due to the proteins added to the food. Critics of GM foods contend that someone who wasn't previously allergic to a food may become allergic, or those who are allergic may be inadvertently exposed to an allergen. For example, someone who isn't allergic to tomatoes, but is allergic to peanuts, may eat a GM tomato which has been modified using parts of a peanut plant. The FDA requires that GM foods undergo more extensive testing than conventional foods.

To date, the proteins found in GM foods currently on the supermarket shelves have not shown the characteristics of food allergens. A recent study by the National Research Council indicated that while there is no evidence that GM foods are dangerous, they have the "potential for undesirable effects." The council concluded that a better understanding of the potential allergens in the GM foods is necessary.

Read the Riverdeep article, "America Debates Genetically Modified Food" to learn more about the controversy surrounding GM foods.
CNN recently featured an article about GM foods: "Experts debate safety of genetically engineered foods."
Read the FDA's response to the question "Will bioengineered foods cause allergic reactions?"

Effective Treatment
While there is no cure for food allergies, some allergists use enzyme potentiated desensitization (EPD), a form of immunotherapy, to provide relief. Treatment consists of a series of injections of common allergens combined with the enzyme B-glucuronidase. As immunities are built up against the allergens, the patient feels better, shows fewer symptoms, and eats whatever he or she wants.

The AAAAI does recommend the following guidelines for food allergy sufferers:

Avoid the food. Most experts agree that this is the best way to be safe.
Ask about ingredients, especially those that are hidden.
Read food labels carefully. See "Traveling Incognito" above.
Be prepared for emergencies. For those who have experienced anaphylactic reactions, wearing a medical identification bracelet and carrying necessary medication is recommended.

Learn More

The Food Allergy Network seeks to increase public awareness about food allergies through education and research. Its site includes FAQs, media reports, and resources for allergy sufferers.
The National Institute of Allergy and Infectious Diseases (NIAD) Fact Sheet on Food Allergy and Intolerances begins with a discussion of common food allergies and describes diagnosis and treatment methods.

Related Resources
Take a look at the following books:

Special Diet Celebrations: no wheat, gluten, dairy, or eggs by Carol Fenster.
Food: Your Miracle Medicine by Jean Carper.