Decoding Food Allergies: Break the Code
Do you want to know how severe your milk, egg or peanut allergy can be? These tests can help!
Allergies to egg, peanut and cow’s milk are among the most common food allergies affecting children. These reactions can range from serious, life threatening reactions (such as anaphylaxis) to milder reactions such as hives. But, how do you know if the reaction will be mild or severe?
While testing for egg, peanut and milk allergies have been available for many years, there have been limitations. Allergy skin testing has been very useful but only offers insight into how likely a reaction will be. A large skin test reaction suggests a reaction is “highly likely,” but is unable to predict how severe a reaction will be. A negative reaction is helpful in predicting that a food allergy is not present. Advances in food protein science have made it possible for allergists to now help predict the severity of food allergies to milk, egg and peanut. A blood test where serum IgE (the allergic antibody) is measured to certain specific proteins in milk, egg, and peanut is now available. This is called “component testing”. Having these answers may alleviate the fear many patients and their families face every day.
The two major egg proteins individuals with egg allergy may be allergic to are ovalbumin and ovomucoid.
- If a person is allergic to ovalbumin, serious reactions may occur if undercooked egg is ingested but most will tolerate egg in baked goods. Furthermore, the likelihood of resolution of egg allergy is high.
- In contrast, if a person is sensitized to the ovomucoid protein, he/she is at risk for a severe reaction and unlikely to develop tolerance over time. Strict egg avoidance is necessary if allergy to ovomucoid is identified while a food challenge in the allergist’s office may be helpful if ovomucoid testing is negative.
There are 2 major classes of milk proteins that can be used in differentiating severity of milk allergy.
- Casein protein in cow’s milk is responsible for severe allergic reactions and less likely to be “outgrown.”
- In contrast, whey proteins (alpha-lactalbumin and beta-lactoglobulin) tend to be associated with less severe reactions and the milk protein allergy typically resolves over time. A milk challenge in the allergist’s office using baked goods containing milk can be a useful tool to assess tolerance.
The proteins in peanuts, Arachis hypogaea, are identified as Ara h and divided into Ara h 1,2, 3, 8 and 9.
- Those individuals allergic to Ara h 1, 2, 3 are more likely to have severe allergic reactions (anaphylaxis) and need to strictly avoid all contact with peanuts and carry self-injectable epinephrine (EpiPen®).
- However, if the allergy is to Ara h 8, the risk is moderate and if sensitized to Ara h 9, the risk is low for anaphylaxis.
Why perform food component testing?
- Testing for the specific protein components of milk, egg or peanut, can help predict the severity of an allergic reaction which can impact the recommendations by allergists when advising patients about safety, lifestyle, and long term risk. While allergy skin testing is still valuable, the availability of component testing via the Pharmacia ImmunoCAP® test by ThermoFisher Scientific offers additional information on which to make important medical decisions and even long term predictions.
At Family Allergy & Asthma Care of Montana, we help patients understand their food allergy and get to the answer— 1 component at at time! These pearls of information were brought to you by Jared Bozeman, Senior Medical Student at The Medical College of Wisconsin.