TORONTO – When Canadians discover they have a strange reaction to a certain food, the first place they head to for clarification is their doctor.
But a new report published Monday in the Canadian Medication Association Journal suggests that blood tests physicians and holistic medicine practitioners conduct can leave patients confused.
There are numerous tests to figure out the link between food and sensitivity, allergy or intolerance. And while many are widely available and can be purchased for hundreds of dollars, most are unstandardized, says Dr. Elana Lavine, an allergist at the Humber River Regional Hospital.
In her study, she points to a common blood test that measures immunoglobulin G (IgG) antibody binding to certain foods.
While this test could show users of “intolerance” to foods, the results aren’t enough for doctors to diagnose an allergy, she said. The study notes that results may sometimes lead patients to believe they are allergic to foods when it isn’t necessarily the case.
“Physicians should caution patients about the controversy surrounding testing for food sensitivity,” she wrote, noting that other experts in Europe and the United States have investigated the “limitations” and “potential misuse” of these tests.
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What confuses patients most is the difference between intolerance, allergy and food sensitivity – and these tests don’t make it clear.
– A food allergy is a specific reaction in the body’s immune system to certain proteins in a food. The reaction can reoccur with exposure to the food in question. The immune system responds to a food it considers harmful by creating IgE and chemicals such as histamines. These chemicals cause reactions in the respiratory system, gastrointestinal tract and the skin.
– An intolerance, on the other hand, is an adverse reaction without an immunological response. Lactose intolerance is a prime example of this. Intolerance, unlike allergies, takes larger amounts of food to trigger a reaction. It’s often mistaken for allergies but intolerance is linked to an inability to digest of absorb foods.
– Food sensitivity, finally, is a general term that can be used for any symptoms that arise that may be related to food consumed.
Lavine says patients should visit their doctors once they receive test results that point to foods to avoid. Physicians also need to tell patients that IgG tests aren’t sufficient enough to diagnose allergies.
Food allergies affect about five to six per cent of young children in Canada and about three to four per cent of adults, according to Health Canada.
According to the federal agency, there are nine foods that trigger most allergies:
– Peanuts
– Tree nuts (almonds, Brazil nuts, cashews, hazelnuts, macadamia nuts, pecans, pine nuts, pistachios and walnuts)
– Sesame seeds
– Milk
– Eggs
– Fish (including shellfish and crustaceans)
– Soy
– Wheat
– Sulphites
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