Diagnosing Food Allergies

The first step in avoiding food allergy reactions and preventing future reactions requires a trip to your doctor, who can record your history, initiate allergy testing, rule out other potential causes, refer you to a qualified allergist, and provide advice and medications to keep you healthy until you can get in to see your allergist.

Then, the real work begins, as your allergist performs a complete food allergy workup to:

  • Pin down food allergy as the cause of your symptoms.
  • Identify the food or foods that trigger symptoms.
  • Rule out foods that are suspected of triggering symptoms but really don’t.

Your family doctor is likely to refer you to an allergist she’s worked with in the past. Many allergists, however, are more accustomed to working with hay fever and other environmental allergies and less with food allergies. Knowing the benefits of a food-allergy savvy allergist Choosing an allergist who’s experienced with food allergies benefits you in three ways:

  • The diagnosis may be quicker and less costly, because the allergist is likely to perform tests that focus on food allergies rather than on a host of other allergies.
  • The allergist may be more aware of the risks of false positive results — test results that show you’re allergic to something you’re not really allergic to. False positives often lead to overly restricted diets that lower your quality of life and may even lead to malnutrition.
  • Because skin tests can cause serious reactions in people with severe food allergies, the allergist is likely to have the necessary emergency medications on hand to properly treat you. (Severe reactions to skin tests are very rare.)
  • The allergist won’t order controversial tests that have been used by charlatans or quacks in the past. These tests can be very expensive and have no real bearing on the ultimate diagnosis of food allergy.

Choosing an allergist with the right stuff If you have input on selecting the allergist, look for a combination of the following qualities:

  • Experience in diagnosing and treating food allergies.
  • Excellent interpersonal skills, so the allergist can effectively work with you to address all your concerns.
  • Covered by your insurance, so you don’t have high out-of-pocket expenses.
  • Availability, so you can see the allergist as soon as possible and are likely to have little trouble scheduling follow-up appointments.

A thorough food allergy workup consists of your medical history, a physical exam, and one or more tests to determine if you are, in fact, allergic to certain foods and to identify the problem foods. Your allergist is likely to perform one or more of the following tests:

  • Skin tests: Skin tests consist of applying a tiny amount of the suspected allergen below the upper layer of the skin, usually by scratching or pricking the skin. A skilled allergist tests only the foods he suspects may cause reactions, based on the results of your history and physical exam, so no more than a few pokes with a needle are ever required.
  • Blood tests: Your allergist may draw a vial of blood and test it for the presence of antibodies that indicate the probability of an allergy to a specific food. These blood tests are commonly referred to as RASTs (short for radioallergosorbent tests) but more accurately called immunoassay for specific IgE.

IgE (or Immunoglobulin E ) is a type of antibody that your immune system produces to attack a particular allergen. For each allergen, your body produces a different IgE, so if you’re allergic to milk, your blood has IgE to attack allergenic substances in milk.

  • Food challenges: To confirm a positive test result or gather more diagnostic data, your doctor may perform a controlled food challenge, in which you consume increasing amounts of a suspect food under your doctor’s close supervision.

Don’t try a food challenge at home. Food challenges carry a risk of serious reactions. Only trained personnel with emergency treatment immediately available should perform the test.

Your body may react to certain foods in ways that can trick you into thinking you have an allergy when you don’t. Instead of a food allergy, your body may lack the necessary chemicals to digest a particular food, which is considered an intolerance, not an allergy.

Lactose intolerance is one such example, in which the body doesn’t have the enzyme (lactase) it needs to break down milk sugars. A lactose intolerant person is likely to experience stomach cramps, nausea, and vomiting the same symptoms that may afflict someone who has a milk allergy but the diagnosis and treatments are very different.

With lactose intolerance, you can avoid milk or take a lactase supplement to enable you to digest the milk sugars. With a milk allergy, avoiding milk products and treating symptoms in the event of a severe reaction are the primary treatment options.