Q: My daughter is allergic to tree nuts, particularly cashews and pistachios. We’re a little confused about safe spices. Would sumac (used in Middle Eastern cuisine) and nutmeg be safe for her to eat?
Dr. Sharma: Spice allergy appears to be uncommon, although it may be under-diagnosed. A recent review estimated that it affects between four and 13 of 10,000 adults. People with spice allergy are often allergic to pollens, and develop allergies to specific spices because of similarity in the structure of proteins in the spice and the pollen.
If someone has had a suspected reaction to a spice, testing may be attempted by an allergist, but it is not standardized. Often an oral food challenge — in which tiny, then gradually increasing amounts of a food are eaten under supervision — would be needed for a definitive diagnosis.
To answer your specific questions about spices and tree nut allergy, first nutmeg is not a nut and does not need to be avoided by those with tree nut allergy. (Unless there’s a tree nut “may contain” warning on a package label.)
Sumac is a spice used in Middle Eastern cuisine made from grinding the fruit of the sumac plant. The sumac plant is in the same family (Anacardiaceae) as the trees from which cashew, pistachio and mango are derived. There appear to be no published reports of allergic reactions to sumac spice in those with cashew or pistachio allergy.
Regarding mango, some people with cashew or pistachio allergy have cross-reactivity to mango, but others do not. The same variance could potentially hold true with sumac spice, but there aren’t case reports to use in assessing the risk.
If you wish to introduce sumac spice, discuss with your child’s allergist what the most appropriate plan would be, potentially in the setting of an oral food challenge.
Dr. Sharma is an allergist, clinical researcher and assistant professor of pediatrics. He is Clinical Chief of the Division of Allergy and Immunology at Children’s National Health System in Washington, D.C. and Director of the Food Allergy Program. Questions submitted below will be considered for answer in the magazine.