What Is Food Allergy Testing?

Food allergy testing is a medical procedure for determining whether a person is unusually sensitive to one or more common food items. This sensitivity can trigger an immune response, ranging from mild to severe, when foods of this type are consumed. In the most extreme cases, food allergens can be dangerous, resulting in anaphylactic shock and premature death. Food allergies are more common in children than adults. According to the Centers for Disease Control and Prevention, roughly one in 20 American children has a dietary allergy of some kind.

Food allergies represent a potentially serious health risk. If you believe that you or another family member has a food sensitivity, schedule an appointment with a Baptist Health allergist. He or she can diagnose the nature and severity of that condition, which will likely include food allergy testing. 

What Is a Food Allergy?

A food allergy is a medical condition in which your body treats a substance found in food as an allergen. The allergen triggers an immune response that may include itchiness, sneezing, coughing, diarrhea, abdominal pain, rashes, difficulty breathing, chest pain, swollen mouth parts, bluish skin color, and loss of consciousness. The latter symptoms are associated with anaphylactic shock and are life-threatening. 

A surprisingly small number of food types are responsible for about 90 percent of all dietary sensitivities in the U.S. These include:

• Fish and shellfish
• Dairy products, especially cow’s milk
• Tree nuts, including almonds, walnuts, pecans, macadamias, and hickory nuts
• Wheat 
• Soybean extracts
• Eggs
• Peanuts (which are legumes or “groundnuts”)

Strictly speaking, food allergies are distinguishable from food sensitivities. The latter are less harmful to your health and are chiefly marked by abdominal distress. Food sensitivities can arise in response to items that contain MSG, lactose, or gluten. (One version of the latter, celiac disease, is more serious than a typical food sensitivity.) 

What Types of Food Allergy Tests Are There? 

Your allergist will likely take the following steps to diagnose a food allergy:

• Medical history and exam: Your allergist will begin by asking about your symptoms. He or she will want to know what they were, when they occurred, how long they lasted, their intensity, and which foods were possibly involved. Your allergist will also be interested in your personal and family medical history, including whether any blood relatives have food allergies.
• Skin prick test: A skin prick test is used to determine whether you are allergic to a food or foods in your diet. Tiny samples of the food allergen are placed under the surface of the skin by means of needles or pins. Any sample that causes your skin to react by swelling or turning red may be categorized as an allergen.
• Allergy blood test: Allergy blood tests, also called RAST tests, measure the volume of immunoglobulin E or IgE antibodies in the bloodstream. IgE antibodies are associated with immune reactions to allergens. 
• Oral food challenge: Another means of testing for food allergies is the oral food challenge. Your allergist will provide you with a series of samples of a suspected food allergen, watching you for any signs of an immune response. The samples will gradually increase in size until they trigger an immune response or it is determined that no food allergy exists for that item. Because there is a slight safety risk, oral food challenges are only undertaken in a physician’s office or other medical facility, under professional supervision. 
• Trial elimination diet: A trial elimination diet works in the opposite fashion of an oral food challenge. Your allergist will identify foods in your diet that should be eliminated for a period of two to four weeks. He or she will monitor your health during this time period. If your allergy symptoms recede during the trial elimination diet, then the food-item that you’ve ceased eating will be indicated as an allergen.

Allergy testing is an effective diagnostic tool but not without limitations. Results can be altered by medications you’re taking – for example, an antihistamine to control allergy symptoms. If possible, you should stop taking an antihistamine before the skin prick test. 

Additionally, skin prick and blood tests, though producing few false negatives, are more likely to produce false positives (that is, an indication that you’re allergic to certain foods when in fact you’re not). This is one reason allergists also order food challenges and elimination diets. These are the most accurate indicators of food allergies, especially when combined with information from your medical history and the skin prick and blood tests. 

How Is a Food Allergy Treated?

Your allergist will use the data he or she has collected from your examination and testing to determine what foods, in any, are your allergens. The treatment for any food allergy you are diagnosed with is to avoid that food altogether. There are no immunizations or other cures available. You’ll need to educate yourself on appropriate dietary choices, as well as reading the list of ingredients on foods that you buy. A professional dietician can help you with these lifestyle changes. Individuals with severe food allergies may also need to carry an epinephrine device with them at all times, in case of a medical emergency. 

When Should I See a Physician for a Food Allergy?

If you’re dealing with a food allergy, don’t wait on diagnosis and treatment. Schedule an appointment with a Baptist Health allergist. If your food allergies are potentially life-threatening and you start to develop symptoms, go to the nearest emergency medical facility.