When it comes to food allergies, tree nuts are one of the most common culprits. But while millions of Americans claim to be allergic to cashews, Brazil nuts, hazelnuts and walnuts, a new study suggests that even if you have been diagnosed with a specific nut allergy, it turns out you may not be allergic to all nuts.
According to new research published in Annals of Allergy, Asthma and Immunology and reported on by Time, more than half of people diagnosed with a nut allergy don’t show allergic symptoms to all types of nuts, even if an allergy test says they will. So, just because someone has an allergic reaction to one type of nut doesn’t
Tree nut allergies can cause reactions ranging from itchy lips and throat to full-on anaphylactic shock, so they are nothing to mess around with. But are we being a little overly cautious?
Researchers analyzed 109 people who tested positive to tree nut allergies on blood and skin tests done in the past eight years. They then conducted a “don’t-try-this-at-home” experiment — feeding them the nut they were supposedly allergic to — with individuals who knew from experience they were allergic to one nut but also tested positive for another (even if they had never consumed that nut). For instance, if a subject had experienced an allergic reaction to an almond and an allergy test said he was also allergic to walnuts but had never eaten a walnut, the researchers fed him a walnut. The results were surprising.
“Despite showing a sensitivity to the additional tree nuts, more than 50 percent of those tested had no reaction in an oral food challenge,” explained lead study author Dr. Christopher Couch, a member of the American College of Allergy, Asthma and Immunology.
Dr. Couch and his team believe this may be explained by the fact people are sensitized to the allergen — they have antibodies that react in testing but don’t show symptoms when the food is actually consumed — and that regulated oral food challenges should be conducted to accurately diagnose additional nut allergies.
“We found even a large-sized skin test or elevated blood allergy test is not enough by itself to accurately diagnose a tree nut allergy if the person has never eaten that nut,” said co-author Dr. Matthew Greenhawt, chair of the ACAAI Food Allergy Committee. “Tree nut allergy should only be diagnosed if there is both a positive test and a history of developing symptoms after eating that tree nut.”
The study also showed that almost all the people who tested positive to peanut allergies were safely able to eat other tree nuts — including almonds and walnuts — despite other tests claiming those nuts may be an issue. Peanuts, after all, are legumes not tree nuts.
Oral food challenges should obviously not be conducted at home and only under the watch of a trained, board-certified allergist, as reactions can range from mild itching to severe anaphylaxis — which can lead to death.
But before you all shun nuts for good, you may want to consider making an appointment with your allergist ASAP.
What Do YOU Think?
Do you have personal experience with food allergies? Do you think monitored food challenges should be mandatory when diagnosing allergies?