New research on a more accurate peanut allergy blood test is finding that many people who think they have allergies to the nuts actually don't.
Testing for peanut allergies can be frustrating since current skin tests are notoriously inaccurate. The test involves rubbing small amounts of peanut on the skin and then taking a blood test to measure levels of antibodies that develop in reaction to the peanut.
While those who develop severe reactions are easy to identify, it's sometimes unclear whether those who have milder reactions truly have a peanut allergy.
But this new blood test can identify 97 per cent of those at risk of severe allergic reactions from peanuts, says its developer, a company based in Sweden called Phadia AB.
The test is different from current methods because it detects antibodies to a very specific part of the peanut that triggers reactions, called Ara h 2. Only those allergic to that molecule are thought to be truly allergic to peanuts.
In controlled experiments, scientists at the University of Manchester tested almost 1,000 eight-year-olds. Some of the children were given cookies with tiny amount of peanuts and some were not.
Although 110 of the children, or about 1 in 10, had had a positive test to peanuts, most of them didn't suffer a reaction to the peanuts in the cookies. Only 19, or one in 50, suffered a reaction after eating the cookies. (Doctors were on site to treat the reactions.)
It turned out that most of the rest of the children thought to have peanut allergies in fact had hay fever or were allergic to grass or tree pollen.
Peanut allergies produce some of the most severe reactions of any allergy. Even the smallest trace can be enough to set off a sometimes fatal allergic reaction, called anaphylaxis.
Unlike other food allergies, such as those related to eggs and milk, which appear early in life and are usually outgrown by school age, peanut allergy tends to be lifelong.
Recent reports suggest that the number of children begin diagnosed with peanut allergies is on the rise, although no one knows why.
Prof. Adnan Custovic, who led the research, which is published in the Journal of Allergy and Clinical Immunology, says the new test should help reduce the number of kids diagnosed with peanut allergies, and thereby reduce the stress on their parents.
"Avoiding peanuts is the best way of managing allergic/anaphylactic reactions to peanuts. Complete avoidance is difficult to achieve due to the widespread use of peanuts in prepared foods, and accidental exposures are common and may be life-threatening," he said in a news release.
"The fear of possible reaction markedly reduces the quality of life amongst peanut-allergic patients and their families. However, avoiding peanuts only makes sense if child is really allergic."
Beatrice Povolo, the director of programs and services at Anaphylaxis Canada, says her group would welcome any kind of more accurate test, but she notes that the method described in this test still have to be tested further.
She adds that Canadian parents have access to good testing now.
"In Canada right now, there is a good process in place in terms of testing. An allergist will look at skin prick testing, blood tests, the clinical history of the patient as well. When they look at all of those factors, they can come up with a diagnosis," she explained to Canada AM.
