Cutting the Mustard
So why did Health Canada choose to add a food like mustard seed to its list? According to Food Allergen Program Manager Michael Abbott, the government agency not only looks at which allergens are the most common, but which ones are mostly likely to produce the most severe reactions, because they especially need to be clearly labeled on food packaging.
Then, to narrow down the possibilities, Health Canada uses specific, science-based criteria: things like double-blind, placebo-controlled food challenges to confirm the allergy; case reports from physicians; evidence that demonstrates serious allergenicity even in small quantities; and proof that the food is commonly used in Canada.
Although several foods, including onions and garlic, were in the running, only mustard ended up making the cut because there was sufficient scientific evidence to show its allergenicity, and because while allergies to mustard are rare – a small fraction of peanut allergy rates, in fact – the reactions tend to be serious.
As well, mustard is often hidden in ingredient terms such as “spices” or “natural flavours”, making it especially difficult for allergic shoppers to protect themselves.
“We’re trying to minimize risks associated with inadvertent consumption of these allergens and maximize choices for people who don’t want over-labeling,” says Abbott. Not surprisingly, Health Canada also regularly hears from people with serious allergies to foods that haven’t made the list. “I feel for those people as well. But we are trying to address the foods that are most commonly associated with severe adverse reactions so we get the maximum benefit.”
Like Peas in a Pod
Currently, Health Canada is not seriously considering any other allergens for its priority list, but Dr. Ham Pong believes the list will have to continue to grow and adapt as our diets, and our bodies, change over time.
Sunflower seeds are common culprits in his practice – far more than mustard seeds – and he also has his eye on legumes such as lentils and chickpeas, which are top allergens in countries including India, where they form a staple part of the diet. He also expects to see more allergies to tropical fruits such as kiwi, mango, lychees and longans as their popularity in North America grows.
Dr. Susan Waserman, an allergist at McMaster University in Hamilton, agrees. In her practice, allergies to lentils and fresh fruits such as kiwi and mango have appeared, whereas they were unheard of in the not-too-distant past, and more parents are reporting severe symptoms with chicken than with wheat.
Waserman emphasizes that these emerging allergies are still relatively rare, and that the top allergens are still the offenders behind the vast majority of reactions – but that is always subject to change.
“It’s a moving baseline. Over the past few decades, people have become more allergic. We have different lifestyles, different exposures, different drugs, different immigrant groups who are coming in with different cooking patterns – and all of these things are likely interacting to affect the natural history of the old allergies or bring up new ones,” says Waserman.
“So I never say never any more. No matter what somebody says they’ve had an adverse reaction to, it’s worth looking into.”