Food allergies are occur because of an immune system reaction to certain foods. 1 in 20 Americans are affected by food allergies and can occur at any age, but most commonly in babies and young children. 90% of food allergies are related to milk, egg, soy, wheat, tree nuts, peanuts, shellfish and fish.
Symptoms
Food symptoms affect every individual differently. The amount of food that triggers allergic reactions differ from person to person as well as the time it takes for symptoms to occur. Some common symptoms of food-related allergic reactions included:
- Digestive problems
- Hives
- Swollen airways
- Anaphylaxis – Can impair breathing, severe drop in blood pressure, and affect heart rate to a fatal degree.
Some patients may react to certain fruits with symptoms of itching and/or tingling feelings in their mouths. This is known as pollen-food allergy syndrome or oral allergy syndrome. For example, if you are allergic to birch pollen then you may have this reaction when eating apples. Pollen-food allergy could also lead to anaphylaxis on rare occasions.
Diagnosis
Food allergy diagnosis requires medical history including what you ate, how much you ate, when symptoms developed, what symptoms you experienced, and how long these symptoms lasted. The doctor may order skin and/or blood tests when making a diagnosis. Our professional allergists use their experience to correctly examine and interpret the results of tests to correctly diagnose a food allergy.
Skin Test
During this test, two small amounts of liquid is applied to arms or back. One will contain the suspected food while the other will be the control site and contain no allergen. Using a small sterile probe, the skin is pricked to allow the liquid to seep under the skin. Minutes later, a hive may form on the test site and will be compared to the control site.
Blood Test
Blood tests are used to find the presence of allergen specific antibodies known as immunoglobulin E antibodies. These tests are used by many allergists but we will make sure your tests are based your personal diet. Without making the blood test personalized the results can be inaccurate and confusing. Our professional allergists are experienced and will properly determine when to administer a blood as well as interpreting the results.
What to Expect and How to Prepare for an Oral Food Challenge
If your allergist believes you or your child might not have a food allergy the next step is to perform an oral food challenge (OFC). OFCs are used when a careful medical history and allergy tests, such as skin and blood tests, are inconclusive. A food challenge is considered the gold standard for food allergy diagnosis and consists of eating gradually increasing amounts of the food in question under medical supervision. The risks of an OFC include experiencing mild symptoms like itching, hives, and nausea to more severe symptoms including anaphylaxis. Most reactions to food challenges results in skin or stomach symptoms and are usually mild because the concerning food is fed gradually and is stopped at the first sign of reaction. Your allergist will have all the necessary medications on hand to treat a reaction, including epinephrine just in case.
An OFC typically lasts a few hours so come prepared with tablets, books, and other engaging activities to help pass the time and aid in distracting younger children. Parents should be encouraged to bring their child’s favorite cups, plates, and utensils from home to create a sense of familiarity. You need to be in good health on the day of the test and underlying chronic allergic conditions such as asthma, atopic dermatitis (eczema) and allergic rhinitis (hay fever) have to be well controlled, so they do not interfere with the interpretation of any symptoms. Don’t forget to bring your epinephrine autoinjector with you for the car ride home in the unlikely event of a delayed allergic reaction after you have left the office following the food challenge. Both intranasal and oral antihistamines should be stopped a few days before the OFC since they might mask mild early symptoms. Do NOT stop any asthma or topical eczema medications. Avoid scheduling OFCs during times of year where your seasonal allergies are poorly controlled.
Make sure you talk to your doctor to determine who is responsible for providing the food for the day of the challenge. Some allergists may ask you to provide the food or the office may provide it for you. If you are responsible for bringing food, make sure it’s not processed in a shared facility or processed on a shared line with something else you’re allergic to. For infants, younger children, or picky eaters, you may need to have several food options ready to minimize the possibility of food refusal. Have food options available in both liquid and solid forms along with tasty mixers and condiments to mask bad tastes including ketchup, chocolate sauce, applesauce, candy, etc. Please do not pre-mix the food unless otherwise instructed as the allergist needs to accurately measure out how much is being ingested.
Make sure to have a light meal or no meal prior to the challenge. This is especially important for young children to encourage a more robust appetite on the day of the appointment. The OFC starts with a small serving of the food followed by a wait period of around 15-30 minutes. If no symptoms are present, a slightly larger amount is provided. This pattern repeats around 4-6 times until a meal sized portion of the concerning food is eaten. Expect a physical examination and vital sign measurements at the start of the challenge and repeated intermittently throughout the day. These values help objectively monitor for any changes during the course of the challenge.
If you pass your OFC it is recommended that you continue to include this food in the diet on a regular basis moving forward. Having an allergic reaction after a passed OFC is very uncommon. Of course, if you fail the OFC continued strict avoidance is recommended.
Oral Immunotherapy (OIT)
In the past, the management of food allergy centered exclusively on strict avoidance. Allergen-specific oral immunotherapy (OIT) aims to induce desensitization leading to tolerance and eventually sustained unresponsiveness to foods that patients have been found to be sensitized to by skin or blood testing. This innovative treatment marks a major change in the field of Allergy and Immunology and has had a major impact in the lives of our food-allergic patients and their families. For more information call our office and schedule an appointment or see our Food Oral Immunotherapy section on our website.