Q: If I’m allergic to one type of tree nut, do I have to give up all nuts?
A: Not necessarily. The American College of Allergy, Asthma and Immunology (ACAAI) says you should consider doing an oral food challenge (see below) to find out if you’re allergic to other nuts.
To be on the safe side, allergists often advise patients to avoid all nuts, including peanuts, if they have a reaction to one kind of nut. (Peanuts are legumes that share common allergenic proteins with several tree nuts.)
But a 2017 study in ACAAI’s medical journal, which looked at the medical records of 109 people with a known allergy to a single nut, found overall that more than 85 percent of the subjects who had positive reactions to tree nuts on skin prick or blood tests passed an oral food challenge to nuts they had never eaten. This was especially true for people with peanut allergies who reacted in skin prick or blood tests. And everyone passed the almond challenge.
Skin prick and blood tests show only that you have been sensitized to a given substance, not that you will necessarily have an allergic reaction if you ingest it. As the ACAAI notes, the surest way to confirm (or disprove) a food allergy is with an oral food challenge, which involves consuming increasing amounts (starting with a tiny amount) of the suspected allergen to see if you have a reaction. This must always be done under medical supervision in an allergist’s office, since the test has the potential to cause a severe, even life-threatening, reaction. And you should never introduce or reintroduce into your diet any nuts that are considered a possible risk before being retested and given an oral food challenge.
This article first appeared in the UC Berkeley Wellness Letter.
Also see Preventing Peanut Allergies.