Dear Pharmacist: I had such a bad reaction to eating hazelnuts that I required a shot, and some steroids. I don’t eat much nuts, sometimes cashews. Do you think I’m allergic to all nuts? --C.J., Coral Springs, Fla.
You should avoid other nuts too, I’ll tell you which in a minute. Luckily, you didn’t have full-blown anaphylaxis which occurs in about one third of all tree nut ingestions, especially with peanuts, which by the way are actually legumes. It shocks me that airlines still serve peanuts to passengers -- hundreds of people at a time -- when there is such an incredibly high sensitivity rate!
The allergic response is triggered by the proteins found in the nuts, which do not break down with heat, meaning you can’t cook them out. Nuts are often “hidden” too, so they may only get honorable mention in popular foods such as cookies, protein bars, cakes, cereals, nut spreads, praline and other desserts. Also, if the label says, “This product was manufactured in a facility that also uses nuts....” that’s your cue to put the product back because there are traces of nut proteins that may have blown around the facility and made it into your particular food during handling or manufacturing.
Some folks only experience a mild problem with nuts, and it’s limited to irritations of the mouth, lips, tongue or throat. This is called “OAS” for oral allergy syndrome, or sometimes “Pollen Food Allergy.” Clinically, we see this most frequently in people allergic to weeds because the body sees the pollen traces in the nut. Birch pollens are sometimes to blame in OAS, which can occur any time of the year, but usually during pollen season. The cross sensitivity can occur between birch and other nuts as well as plums, pears, cherries, apples, carrots, peas and sunflower seeds.
I found a study that measured human IgE antibodies in order to evaluate cross-sensitivities. Among tree nuts, there is a strong cross reaction between walnuts, pecans and hazelnuts. So none of those for you!
There’s a moderate cross reaction with these: Pistachio, almonds, hazelnuts, cashews and Brazil nuts. Of the bunch, cashews and pistachios are pretty tightly correlated, so if you’re allergic to one, definitely stay away from the other. I’d avoid the bunch honestly, and consider a blood test to determine food allergies.
One more warning, about my favorite “nut” which I hardly ever eat but still fantasize about. Cashews, they are really seeds, not nuts. If you’re highly allergic to poison ivy, stay away from these guys. Even the “raw cashews” you see at health food stores are not truly raw. You simply cannot eat a raw cashew, it must be separated from it’s double-shell. In a painstaking process it’s steamed and/or boiled but, the outer shell contains urushiol, a toxic resin that sparks the familiar skin rash after exposure to poison ivy, oak and sumac. If you have a severe allergy to poison ivy, raw cashews should probably not be consumed, otherwise eat one for me!
This information is not intended to diagnose, treat or cure your disease. Suzy Cohen is a registered pharmacist. To ask her a question or to learn more about your health, visit DearPharmacist.com.