A food allergy is an abnormal reproducible response of the body's immune system to certain aspects of specific foods that cause potentially dangerous allergic reactions.
Food allergies are caused by the immune system. Food intolerances refer to non-immune mediated adverse reactions to foods. One example of food intolerance is lactose intolerance, a metabolic deficiency of an enzyme required to metabolize lactose. Another example of food intolerance is scromboid poisoning which is a reaction that can mimic an allergic reaction but is triggered by a toxin (not IgE mediated) found in seafood. It is crucial to distinguish between food allergy and food intolerance because in general, a food intolerance does not increase risk of progression to anaphylaxis (potentially severe life threatening allergic reaction).
Food allergies are most commonly caused by allergic antibodies (IgE) to the problem food(s), but may result from other specialized immune pathways (non IgE mediated or mixed IgE and non-IgE mediated) such as eosinophilic esophagitis, celiac, atopic dermatitis or food protein enterocolitis (FPIES). Interactions between the problem food and allergic antibodies (IgE) cause an allergic reaction by the release of histamine and other inflammatory chemicals which cause the symptoms, of varying degrees, typically seen in an allergic reaction - hives, swelling, itching in the mouth, throat irritation, trouble breathing, vomiting, fainting, anaphylaxis.
Allergic symptoms usually begin within minutes of eating the food, but can take up to 2 hours to progress. Since the symptoms of a food allergy may mimic other medical conditions or problems, always consult your doctor for a diagnosis. Common symptoms are listed below:
Anaphylaxis or allergic shock is a medical emergency treated with epinephrine. Call 911 for immediate medical assistance. Those with known food allergies should carry emergency kits with epinephrine auto-injectors.
Most recent studies predict that approximately 6 percent of children and 5 percent of adults in the U.S. have a food allergy. The prevalence of a self-reported allergy is closer to 10 percent. The reason for this difference is probably related to misunderstandings about food allergy.
Yes, the Center for Disease Control and Prevention reported an 18 percent increase in the prevalence of food allergies in U.S. children, from 3.3 percent in 1998 to 3.9 percent in 2008. Many other studies have shown an increase in food allergy. The reasons for this increase are not completely known, and there are likely to be several factors.
The most important tool to diagnosis a food allergy is a discussion with your allergist about the exact details of the reaction. Skin test with food extracts and blood tests for allergic antibodies (IgE) are used to help diagnose food allergies. However, these tests can both over estimate or miss a food allergy so a physician supervised oral food challenge is often required to confirm the diagnosis.
Food challenges are physician-supervised procedures that allow for definitive diagnosis of food allergy when the diagnosis is unclear. The location and specifics of the food challenge depend on the exact details of prior reactions and results of skin tests and blood tests for allergic antibodies.
The procedure begins with a tiny amount of the problem food. Throughout the challenge, there is direct supervision and monitoring for early signs of allergic reactions. Reactions are treated with allergy medications just like accidental ingestions. The dose is slowly increased until the person undergoing the challenge has a reaction or the goal dose is tolerated without symptoms.
We offer food challenges in the outpatient setting. Some people do test "allergic" or have positive tests to a food (by skin or blood testing) and yet have no symptoms when they eat that food. The food challenge is generally performed when the test results are not clear or sufficient to diagnose a food allergy.
This > 3 hour procedure involves the eating or drinking of tiny doses of a food that we gradually increase over time to see if an allergic reaction occurs. Should the patient have any reaction, we will stop the procedure and treat with supportive therapies.
It depends on the food. As much as 80 percent of children with milk, egg, or soy allergy will eventually outgrow their allergy. A much lower percentage (about 10-20 percent) outgrow nut allergies. Decreased reactions on skin tests and blood levels of the allergic antibody to the food may indicate the allergy is resolving. If you think you or your child's food allergy is improving, or want to find out the status of the allergy, discuss this with your allergist.
Education about avoidance and management of accidental exposures is the cornerstone of living a happy and healthy life with a food allergy. Every person with food allergy should have a Food Allergy Treatment Plan in case of accidental exposure.
Desensitization is NOT A CURE, patients are still considered allergic to the food but the goal is to decrease the allergic immune response with accidental exposure to the food.
UCLA has been awarded as a Center of Excellence by FARE (Food Allergy, Research and Education) since 2015 and continues to be an active Center of Excellence in the Food Allergy, Research and Education (FARE) Clinical Care Network. As a member of the FARE Clinical Care Network, UCLA collaborates with research centers across the country to ensure that our patients have access to state of the art diagnosis, treatment and research in food allergies.