Food allergies most commonly affect the gastrointestinal tract, the skin and the respiratory system. Typical symptoms include:

• nausea
• vomiting
• diarrhea
• skin rash
• breathing difficulty
• sneezing
• itchy, watery eyes

In severe cases, anaphylactic shock may occur even if the allergic person has consumed only traces of the offending food. The signs of anaphylactic shock include itching and flushing of the skin, followed by severe vomiting, diarrhea, hypotension and constricted respiratory passages.

Less sensitive people may be better able to tolerate small amounts of the allergens in the foods they eat. They also may tolerate the allergen if they are not under stress.

Who Gets Food Allegies?

Although two out of five Americans believe that they have food allergies, only about 1 percent of adults suffer from true food allergies. Children are more susceptible -- up to 7 percent may be affected -- but their symptoms often subside as they get older. Some children who as infants had allergies to certain foods are able to eat them again by the age of 3.

The later in life food allergies appear, the less likely they are to go away. Also, people with allergies to plant foods may have cross-allergies. For example, if they are allergic to peanuts, they may also be allergic to other legumes, such as green peas, soybeans, and lentils.

Diagnosing the Problem

Diagnosis usually begins with a physical examination by a physician certified by the American Board of Allergy and Immunology. The qualified allergist will take a detailed medical history.

To help determine which foods affect you adversely, you might be asked to keep a diary of what you eat every day and record any symptoms you experience. You may also be asked to follow an elimination diet, in which all foods that are not very well tolerated are eliminated. These foods are then gradually re-introduced one by one to see if you develop a reaction to them. This process is called a food challenge.

Other diagnostic tools are skin and RAST tests. Whether foods flagged by a skin test actually cause problems can be confirmed by a food challenge.

If the methods described so far do not reveal the source of your symptoms, the gold standard for evaluating allergies is the double-blind challenge test. In this test, the patient takes capsules of dried food suspected of causing reactions, along with capsules containing non-reactive substances; neither the doctor nor the patient knows which is being administered at any given time. If symptoms occur only with the food being tested, the patient is allergic to that food. Double-blind challenges are valuable because they can detect and rule out allergies or intolerances to many foods and other substances such as additives. They also eliminate non-food influences that can cause symptoms, including psychological factors.

Clinical ecologists, cytotoxic testing and sublingual testing are not recommended for reliably determining true food allergies.

What You Can Do

Once a food allergy has been diagnosed correctly, the only effective treatment is strict avoidance of the offending food. This can be tricky if you are allergic to something which is used as one of several ingredients in a dish and which cannot easily be detected by sight or smell. (Peanut oil is a good example.) Here are some suggestions that will help keep you from inadvertently ingesting a food to which you are allergic.

If you are in a restaurant, take the following precautions to help insure a reaction-free experience:

1. Identify your allergy.
2. Ask how the dish was prepared.
3. Never taste food before asking questions.

When you are at the supermarket, you also need to be aware of how your allergy affects your choices. For instance:

1. Always read the labels on packaged foods.
2. Become familiar with unfamiliar names used on labels; below is a chart that lists the names for common food allergens:

   Milk	Eggs	Wheat	Corn
   Lactalbumin	Albumin	Gluten	Corn starch
   Caseinate	Vitellin	Cracked Wheat	Corn Sugar
   Lacotglobulin	Ovovitellin	Graham Flour	Corn Flour
   Sodium Caseinate	Ovomucin	Durum Flour
   Curds	Ovomucoid
   Casein	Globulin
   Whey	Livetin

3. If you have questions about favorite foods, contact the manufacturers of the product.

Your allergist may recommend a consultation with a registered dietitian to help you make food choices.

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