Tree nut allergies are often over-diagnosed, says a news study, which suggests that people allergic to one type of nuts aren't automatically vulnerable to the others as well.
The surest way to confirm a food allergy is to get tested for each specific allergen, as opposed to simply assuming your allergic reaction to peanuts extends to walnuts and almonds as well, advise study authors.
According to research leader Dr. Christopher Couch, from the University of Michigan, once their tree nut allergy has been detected via a blood test or a skin prick test, most people resolve to stop eating nuts altogether, and they do so unnecessarily.
His study, published in the journal Annals of Allergy, Asthma and Immunology, makes a clear distinction between food allergy and food sensitivity, and offers evidence that people with peanut allergy are not in fact allergic to other types of nuts.
Nut Sensitivity Doesn't Mean Allergy
To reach his conclusions, Couch and his team investigated medical records belonging to 109 people with documented peanut allergies, who also tested positive for allergies to other nuts.
Although skin prick testing had revealed the study participants were sensitive to tree nuts, more than half of them were able to pass the oral food challenge without exhibiting any allergic reactions.
Moreover, study results showed almost none of the people with peanut allergy were actually allergic to almonds, cashews, walnuts and hazelnuts.
"The practice of avoiding all peanut and tree nuts because of a single-nut allergy may not be necessary," said Dr. Matthew Greenhawt, one of the study authors and Chairman of the Food Allergy Committee within the American College of Allergy, Asthma and Immunology or ACAAI.
As the research points out, if people allergic to one type of nut pass the oral food challenge regarding the others, they can safely include them in their diet.
Oral Food Challenge, Most Accurate Diagnostic Tool
In a recent news release, ACAAI states skin prick tests are not very precise in identifying food allergies, which is why the most accurate type of investigation remains the oral food challenge.
During this particular allergy test, the patient consumes small quantities of the specific food, gradually increasing the amount to discover what — if any — dosage could potentially trigger an allergic reaction.
As per Dr. Greenhawt's explanations, even large-sized skin tests are not conclusive enough to diagnose tree nut allergies without the patient ever eating that particular nut. He adds that a definitive diagnosis for tree nut allergy can't be pronounced unless the patient has had both a positive test result and a history of developing symptoms after the oral food challenge.
Earlier this year, the ACAAI changed its guidelines to recommend that parents introduce peanuts in their children's diet as early as six months old in order to shield the little ones from a potential future allergy.