Food allergies can involve many types of responses; you may get a rash when eating a certain food or it could be life threatening, like anaphylaxis. Finding foods that will not cause an allergic reaction for you or your child when dealing with multiple food allergies can be challenging. You may be afraid that trying a new food will cause another serious reaction, and may ask your allergist what foods are “safest” to try first. Allergists wonder about reactions to new foods the same way you do! So how does one approach such a stressful situation?
Having allergic reactions to two foods that have related proteins is called “cross-reactivity” and the reactions can be called “cross-reactions.” It can be hard for a medical team to tell families what new foods are “safest” to try, and which ones pose a greater likelihood of cross-reactions. To help, allergists have conducted research into how likely people with a given food allergy are to react to other foods. Family allergists may use this data to help determine what advice to give their patients about trialing new foods. In some cases the data reveals a significant chance of having an allergic reaction (or at least a positive allergy test) to a new food that’s related to another food. For example, if you are allergic to cashews, you may also be allergic to pistachios and/or mango.(1) There are many "families" of foods that may be linked, so it is best to consult with your healthcare provider to determine the extent of your food allergy and the potential for cross-reactivity.
How to Spot Foods That Might Cause Allergic Cross-Reactivity
The table to the right shows the potential cross-reactivity between some common, related foods, and was developed by an allergist at the Jaffe Food Allergy Institute at the Mount Sinai School of Medicine in New York.(2) Clinicians might use a table like this when answering questions from families about the likelihood of an allergic reaction to a new food.
To use this table, a clinician would look for your food allergen in the left column. The column on the right gives an indication of the risk that there will be an allergic reaction to one of the foods that are listed in the center column. For example, for a patient allergic to cow milk, the available research shows there is a 92% chance the patient will have an allergic reaction (or a positive allergy test) to goat milk, but only a 4% chance of an allergic reaction to mare (horse) milk and a 10% chance of an allergic reaction to beef and beef products. It may be low risk to eat a hamburger if you have an allergy to cow milk but it will be unknown unless you try.
As always, speak to your healthcare team to discuss your food allergies and those foods that the team is comfortable for you to consumer and those that they would like you to avoid.
What is the best way to introduce new foods to the diet?
As always, consult with your healthcare provider to discuss your food allergies and those foods that are ok to introduce and those that may be potentially harmful. There may be some foods that they are comfortable to have you introduce in small amounts at home, often waiting for a few days before introducing another new food. However, an oral food challenge may be recommended for those who experience anaphylaxis or other severe reactions with foods. Oral food challenges should only be done under strict medical supervision (e.g. in a doctor’s office) and involve trials with small amounts of the food causing the allergy or a potential cross-reactive food. Pending the results, you may or may not be able to consume that food in the future.
Do you or your loved ones have experience with allergic reactions to related foods?
-Ellen Avery, MS, RD, CNSC
2. Sicherer SH. Clinical implications of cross-reactive food allergens. J Allergy Clin Immunol. 2001;108(6):881-90.