Canadians who are well-educated and come from smaller families are almost twice as likely to face dangerous food allergies compared to others, a new Canadian study suggests.
Cleaner homes, less exposure to pets and livestock and an increased reliance on antibiotics could be why those from educated households are more susceptible to food allergies, McGill University researchers say in a study published in the Journal of Allergy.
“It’s the hygiene hypothesis. This change in lifestyle, less exposure to infection, less crowded households – we’re skewing our immune response to what we regard as allergies,” lead researcher, Dr. Moshe Ben-Shoshan told globalnews.ca. Ben-Shoshan is a professor at McGill and allergist at Montreal Children’s Hospital.
Ben Shoshan’s team collaborated with McMaster University to conduct a cross-country telephone survey, speaking with 3,613 households between May 2008 and March 2009 to ask families about nut, fish and shellfish allergies. The researchers then sifted through data on 9,667 people.
Results showed that children had higher rates of various nut allergies compared to shellfish while allergic reactions to seafood spiked in urban settings.
Post-secondary graduates were almost twice as likely to have tree nut allergies compared to others. Immigrants were about half as likely to have any allergies at all, Ben-Shoshan said.
Peanut, tree nut, sesame, fish and shellfish were the selected triggers because they are responsible for the majority of fatal reactions worldwide.
The study is the first in North America to examine the link between allergies and the influence of education, immigrant status and geographic location.
Dr. Stuart Carr, an Edmonton-based pediatric allergist/immunologist, said that while the study’s findings aren’t conclusive, they offer some explanation.
“This is one of many markers that identify a subgroup that seems to be at an increased risk of allergies,” he said, pointing to timing of introduction to food, exposure to infections at childhood and usage of antibiotics as other factors at play.
Carr is also president of the Canadian Society of Allergy and Clinical Immunology, which represents the country’s allergy experts.
He said educated parents may have followed recommendations from global pediatric associations that had urged the public to delay feeding certain foods to their infants.
The guideline was adopted worldwide as a precaution to avoid allergies, but subsequent research found that introducing foods to children later could lead to increased risks of allergy.
“It became the default feeding regulation around the world. Not only was this not well-founded, but it turned out to be the opposite,” Carr said.
Ben-Shosha said his team’s next steps include conducting another telephone survey that will explore environmental factors across Canada that could increase allergies.