Food Allergy and Food Tolerance Tests

The chance of having a food allergy or food intolerance is greater if you have a personal or family history of food intolerance and allergies in general. Do you find yourself avoiding different types of food just in case you are allergic to one or more of the ingredients? Food allergies and food intolerances can make everyday life difficult. You may already know that there are tests to help your doctor diagnose and treat your condition. Learn the ins and outs of the different types of tests.

Do I Need Food Allergy and Food Tolerance Tests?

Food allergies and food intolerances are often difficult to tell apart because they can have similar symptoms. However, there is no single test to diagnose food allergies and food intolerances. Your doctor can order a variety of food allergy and food tolerance tests to help confirm the cause of your symptoms and the best treatment. Whether you decide to have the tests depends on how severe your symptoms are and how much they impact your everyday life. If you feel quite sick after eating one or more different foods, you may want to explore your symptoms further with a physical exam as well as a series of tests.

Before your doctor orders food allergy or food tolerance tests for you, he or she will examine you and request a medical history. Be prepared to explain your symptoms in detail and provide a personal and family history of allergies, asthma, eczema, and autoimmune diseases, such as lupus. You may also need to keep a food log to record the foods you eat, your symptoms, how severe they are, and when they occur.

Your doctor may send you to a specialist to run tests and make a final diagnosis. This may include an allergist or a gastroenterologist, a specialist in diseases of the digestive tract.

What Are Food Allergy Tests?

Your doctor may order one or more of the following food allergy testing to help detect a true allergic reaction to certain foods:

• Elimination diet involves eliminating suspect foods from your diet for a week or more. Foods that you may need to remove from your diet include eggs, fish, milk, peanuts, shellfish, soy, tree nuts, and wheat. You may also need to eliminate other foods that might cause a problem, such as gluten. You then add the foods back into your diet one at a time to see which foods cause symptoms.

• Skin prick test involves pricking your skin with a small amount of foods and watching for an allergic reaction, such as a bump (swelling) or redness.

• Blood tests measure levels of food-specific IgE antibodies in your blood. These antibodies cause allergic reactions.

• Oral food challenge. In your doctor’s office, you will eat small but increasing amounts of different foods as your doctor watches for a reaction. Foods generally include some your doctor suspects are causing your allergic reactions and others that are likely harmless to you.

The elimination diet and oral food challenge may be dangerous, especially if you have had a severe allergic reaction in the past. They should only be attempted under medical supervision.

What Are Food Tolerance Tests?

Your doctor may order the following tests to help diagnose or rule out certain food intolerances, which are reactions that do not involve an allergic reaction. These include lactose intolerance, celiac disease (gluten intolerance), gluten sensitivity, irritable bowel syndrome, and food additive reactions.

• Lactose tolerance test is a blood test that measures how well your body digests lactose after drinking lactose.

• Hydrogen breath test measures the amount of hydrogen in your breath after drinking lactose. Your body releases excess hydrogen if you can’t fully digest lactose.

• Stool acidity test measures the amount of undigested lactose in your feces.

• Intestinal biopsy involves taking a sample of the small intestine and looking for damage typical of celiac disease.

• Bloods tests measure certain antibodies (tTGA and EMA) made in large amounts by the body in celiac disease.

• Elimination diet involves not eating the suspect food for days to weeks to see if your symptoms improve. Your doctor may have you eat the food again to see if symptoms reappear.