Newsletters

Healthy Child Fall/Winter 2005

All About Food Allergy

Joel Mendelson, M.D., Pediatric Subspecialist
for Allergy, Immunology and Infectious Disease,
Pediatric Specialty Center at Saint Barnabas Ambulatory Care Center

Allergy to food has been increasing in many countries over the past 10-15 years. Up to two million, or eight percent, of children in the United States are estimated to be affected by food allergy. This would result in approximately two children in the average classroom.

With a true food allergy, an individual's immune system will overreact to an ordinarily harmless food. This is caused by an allergic antibody called IgE (Immunoglobulin E).

Food intolerance is sometimes confused with food allergy. It differs from an allergy in that it does not involve the immune system. For instance, an individual may have uncomfortable abdominal symptoms after consuming milk. This reaction is most likely caused by a milk sugar (lactose) intolerance, in which the individual lacks the enzymes to break down milk sugar for proper digestion.

Food allergens - those parts of foods that cause allergic reactions are usually proteins. The most common food allergens are milk, eggs, peanuts, wheat, soy, fish, shellfish, and tree nuts.

Almost all children with milk, soy, wheat, or egg allergy will out grow it before adulthood. Peanut allergy is only outgrown about 21 percent of the time.

Symptoms of allergic reactions to foods
The most common allergic skin reaction to a food is hives, red, very itchy, swollen areas of the skin that may arise suddenly and leave quickly.

Atopic dermatitis, or eczema, a skin condition characterized by itchy, scaly, red skin, can be triggered by food allergy.

Gastrointestinal symptoms of food allergy include vomiting, diarrhea and abdominal cramping,

In infants, irritant, non-allergic, temporary reactions to certain foods, especially fruits, are common. For example, a rash around the mouth, due to natural acids in foods like tomatoes and oranges, or diarrhea due to excess sugar in fruit juice or other beverages, occur with some frequency.

Severe allergic reactions
In severe cases, consuming a food to which one is allergic can cause a life-threatening reaction called anaphylaxis - a systemic allergic reaction that can be severe and sometimes fatal.

The first signs of anaphylaxis may be a feeling of warmth, flushing, tingling in the mouth or a red, itchy rash. Other symptoms may include feelings of lightheadedness, shortness of breath, severe sneezing, anxiety, stomach cramps, and/or vomiting and diarrhea. In severe cases, patients may experience loss of consciousness and shock. Without immediate treatment, anaphylaxis may cause death.

Symptoms of anaphylaxis are reversed by treatment with injectable epinephrine, antihistamines, and other emergency measures. It is essential that anyone with symptoms suggesting possible anaphylaxis get emergency treatment immediately.

Diagnosis
Diagnosis requires a carefully organized and detailed assessment of the problem. First, the allergist/ immunologist will take a thorough medical history, followed by a physical examination. The allergist will inquire about the frequency, seasonality, severity and nature of the symptoms, and will ask about the amount of time that elapses between eating a food and any reaction.

Allergy skin tests may be helpful to determine which foods, if any, are triggering a patient's allergic symptoms. In skin testing, a small amount of liquid extract made from the food is placed on the arm. A scratch is then made through the liquid on the top layer of the skin.

If the patient develops a wheal - a raised bump or small hive - within 20 minutes, this positive response indicates a possible allergy.

Your physician may also use blood tests, called RAST testing or CAP-RAST, to diagnose food allergies. False positive results may occur with both food allergy skin testing and blood testing. Food challenges, described below, are often required to confirm the diagnosis.

If the diagnosis of food allergy remains in doubt, the allergist/immunologist may recommend a "blinded" food and/or food additive challenge test. These tests are conducted under close observation. Usually, the suspected food or a neutral food, called a placebo, is fed to the patient in colorless capsules, or in a nonallergenic slush or pudding. Neither the patient nor the doctor knows whether the suspected food or the placebo is being eaten. This is called a "double-blind" challenge. When properly performed, these challenges are very reliable in establishing a concrete cause and effect relationship between a food and an allergy symptom.

Treatment
1. Avoid the food. The best way to treat food allergy is to avoid the specific foods that trigger the allergy.

2. Ask about ingredients. To avoid eating a “hidden” food allergen away from home, food-allergic individuals must always inquire about ingredients when eating at restaurants or others' homes.

3. Read food labels. It is important for food-allergic people to read food labels carefully and to become familiar with technical or scientific names for foods. Egg may be listed as albumin or milk as casein.

4. Be prepared for emergencies. Those who have experienced an anaphylactic reaction to a food may need to carry injectable epinephrine and antihistamines to treat reactions due to accidental ingestion. People who are commonly around the patient, such as school teachers or daycare workers, should also know how to use the injectable epinephrine. Those with food allergies should also wear an identification bracelet that describes the allergy

5. For more information contact the American Academy of Allergy, Asthma and Immunology, (www.aaaai.org) where all of the above information is available and frequently updated.

For an appointment with any of the pediatric subspecialists, please call the Pediatric Subspecialty Center at (973) 322-7600. For a complete list of pediatric services, please call 1-888-SBH-123.

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