The AIR Care Center for Food Allergy and Eczema
We are dedicated to the better care of children and adults with food allergies and eczema. With devoted office days, more time for patient teaching by physicians, nurses and nutritional consultation, we strive to improve the lives of patients with these chronic conditions. We will have Nutritional Counseling with a Registered Dietitian in Dallas on Tuesdays and in Plano on Wednesdays.
Food allergies are on the rise in our society. The number of children with peanut allergies has doubled over a 5-year period. Although any food can be a culprit, 90% of food allergies are caused by peanuts, eggs, milk, shellfish, wheat, tree nuts, soy and fish. Approximately 12 million Americans suffer from a true food allergy. Many more believe they have a food allergy, but when properly evaluated, are found not to be allergic. Many people unnecessarily avoid certain foods because of mistaken fears. Therefore, a careful evaluation of food allergy can be very beneficial to one's lifestyle.
Thus we at AirCareMD are pleased to announce the opening of our new Center for Food Allergy and Eczema beginning May 1. We invite you to take advantage of our expanded services to improve the health of you and your loved ones.
All About Food Allergies
What foods cause allergies?
Although a person could be allergic to virtually any food, most people with food allergies are allergic to fewer than 4 foods. In children, the most common foods causing significant reactions are egg, milk, peanut, soy, wheat, tree nuts, fish and shellfish. In adults the most common foods are peanut, tree nuts, fish and shellfish. Many people mention strawberries, citrus, corn and chocolate as common allergy-causing foods, but they are actually quite uncommon. However, allergies to seeds like sesame, poppy, possibly mustard and more are increasing.
Who should be tested for food allergies?
Testing should be considered when symptoms such as hives, redness of the skin, itchiness, swelling of the lips or eyelids, throat tightness, wheezing, breathing trouble, coughing, vomiting or diarrhea occur shortly after eating. Some chronic illnesses are sometimes associated with food allergy, including eczema (atopic dermatitis), infantile digestive problems (significant vomiting, diarrhea), and eosinophilic gastrointestinal diseases. Asthma and hay fever are not commonly associated with food allergy.
What do the tests measure?
Skin testing and blood testing done at AIR Care determine the presence of IgE antibody directed to particular foods. (IgE is the allergic antibody which mediates most food allergy reactions.)
Unfortunately, the interpretation of positive tests is not so straight forward. Positive tests indicate that IgE is present but do not, in isolation, prove that a reaction will occur upon ingestion of the food. In fact, people who "outgrow" their food allergy usually continue to have a positive test result to the food for many years.
To further complicate matters, some proteins in foods are cross-reactive with similar allergenic proteins in non-foods (pollen) or in other foods. This cross reactivity can lead, for example, to a positive skin test for soy in a person with peanut allergy, or a positive test to wheat in a person with grass pollen allergy, even though the person has not had symptoms of an allergy to those cross-reacting foods.
Depending on the patient's medical history, skin testing, immunocap (blood) tests, or both may be required.
Skin testing is performed using the prick method. The most accurate testing for fruits and vegetables may involve "prick- prick" testing to the actual fresh fruit or vegetable in the office. Atopy patch testing may also be indicated.
Blood tests measure the specific IgE antibody level using a particular method of RAST test (CAP-RAST FEIA® reported in units called KUA/L, which indicates a concentration of specific IgE). This is the most useful blood test in determining the chance of true reactivity to certain foods. For example, an IgE antibody level of more than 7 KUA/L to egg, over 15 to milk, more than 14 to peanut, and more than 20 to codfish was highly predictive (greater than 95% chance) of having some type of allergic reaction among highly allergic children. Unfortunately, lower values, unless virtually undetectable, may still indicate a potential for having an allergic reaction. This test may prove useful in following levels of particular IgE antibodies over time to see if they are falling (perhaps indicating that the allergy is being outgrown).
As you can see, the interpretation of these tests can be complicated.
Your doctor must always interpret these tests in the context of the individual medical history. Even the selection of which foods to test must also be decided carefully and in the context of the medical history, since up to one-half of positive tests may not accurately reflect an allergy.
The definitive test for food allergy is whether a person can consume that food without an adverse reaction. An oral food challenge accomplishes this by exposing a person to the food, first by smell, then by touch and finally, by eating increasing amounts of it.
Oral food challenges might be used to verify the accuracy of a positive IgE test, to determine if an allergy has been "outgrown," or for a variety of other reasons such as non-IgE-mediated reactions (some gastrointestinal allergies)
Food challenges may be "open" (the food is not disguised and the patient knows what food they are ingesting) or "blind" (the food is disguised and the patient may not know what food is being tested).
A challenge is terminated if an adverse reaction occurs at any stage. All challenges are performed under close medical supervision. Patients should not perform their own food challenges on food they believe have caused a significant reaction in the past.
Outgrowing an Allergy
People do outgrow allergies, so an allergy evaluation can be helpful even if a person has been diagnosed with a food allergy. Milk, egg, soy, and wheat are common childhood allergies that children often outgrow. Peanut, tree nut, and fish allergies are more likely to extend into adulthood, but recent research has shown that some people with peanut and tree nut allergies eventually outgrow them.
Atopic Dermatitis (Eczema)
30% of children with eczema have food allergies which trigger skin flare-ups. Flares of atopic dermatitis are much more difficult to relate to specific foods compared to other symptoms of food allergies. We obtain a careful history and may proceed with blood or skin testing or food challenges.
Eosinophilic Gastrointestinal Disorders
Food allergy plays a key role in eosinophilic esophagitis (90% of patients have foods that cause their symptoms) and some other gastrointestinal disorders. In addition to prick skin testing, atopy patch testing may be necessary to identify food triggers of these illnesses. 75% of patients with eosinophilic esophagitis improve by eliminating offending foods from their diets.