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Consumers urged to reevaluate tree nut allergies

A study finds an allergy to one tree nut doesn't necessarily reflect on all of them

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Consumers with food allergies often have to navigate the world more carefully than others, making sure that they don’t consume anything that could potentially cause a reaction. However, a new study suggests that those who suffer from a tree nut allergy may not necessarily have to avoid all types of tree nuts.

Lead author Dr. Christopher Couch says that taking an oral food challenge is one sure way to see if other tree nuts may be dangerous, and that relying on blood or skin prick tests may not be enough.

"Too often, people are told they're allergic to tree nuts based on a blood or skin prick test. They take the results at face value and stop eating all tree nuts when they might not actually be allergic,” he said.

Oral food challenges

The researchers point out that an oral food challenge is the most accurate way to diagnose any food allergy. The process involves patients eating small amounts of food in increasing doses over a period of time, while under supervision in a doctor's office or clinic. Following ingestion, doctors observe the patient for a few hours to see if there is an allergic reaction.

As a warning, the researchers say that an oral food challenge should only be conducted by trained, board-certified allergists, and that one should never conduct one on their own due to the chance of a potentially severe or life-threatening reaction.

Blood and skin prick tests not enough

Couch and his fellow researchers analyzed the records of 109 people who had a known tree nut allergy to one kind of nut. Participants all took blood and skin prick tests to gauge if other tree nuts that they had never eaten before were also dangerous.

Despite positive results indicating allergic sensitivity to other nuts, the researchers found that 50% of participants had no reaction to the same nuts when they took an oral food challenge. This suggests that previous advice to avoid all tree nuts if a person is allergic to one may have been misguided.  

"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. 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,” said co-author Dr. Matthew Greenhawt.

The full study has been published in the Annals of Allergy, Asthma and Immunology.

Editor's note:  This story summarizes a recent healthcare study. Many such studies are conducted each year and some may reach different conclusions. A single study does not form the basis for changing the course of treatment. You should not make any decisions solely on the basis of this or any other news story, advertisement, or social media posting. Only your physician can advise you.

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