Researchers Jiayun Yao and Hind Sbihi were intrigued by a population health concern they were hearing about anecdotally: that immigrants had fewer allergies upon arriving in Canada, but that their allergy rates increased over time in Canada.
Using data from the Canadian Community Health Survey, UBC school of population and public health researchers Yao and Sbihi, looked at the role that genetics and environmental factors play in the development of allergies.
In this Q&A, Yao and Sbihi discuss their findings, which were recently published in the Canadian Journal of Public Health.
Hind Sbihi
You studied how rates of non-food allergies vary between recent immigrants, long-time immigrants and non-immigrants in Canada. What did you find?
Hind Sbihi: By analyzing data collected in the Canadian Community Health Survey, we found a distinctly lower prevalence of non-food allergies among immigrants compared with non-immigrants.
Among immigrants who had lived in Canada for less than 10 years, only 14.3 per cent had non-food allergies, while the rates for immigrants in Canada for more than 10 years were 23.9 per cent compared with 29.6 per cent among non-immigrants.
What prompted you to study non-food allergies?
HS: We know that there is an epidemic increase in allergies worldwide, although the increase varies geographically.
We knew from previous research that the risk of developing allergies increases in those emigrating from low-income countries to Western countries. With Canada having some of the highest allergy rates in the world, we wanted to know if that was also true here.
Jiayun Yao
Also, in the past decade, there has been a lot of focus on food allergies from the media, public and researchers, but less on non-food allergies. It’s also critical to raise awareness for allergies that are a result of other routes of exposure such as inhalation and contact with skin.
Which non-food allergies are on the rise and how do they impact health?
Jiayun Yao: Allergic rhinitis, more commonly known as hay fever, is a good example of non-food allergy. One out of every five Canadians is affected by this condition, which not only affects the quality of life of Canadians but also incurs health-care costs to manage and control the symptoms. Often, people with this condition may also develop co-existing allergic conditions such as asthma, respiratory infections and breathing difficulties during sleep.
What do your results tell us about the link between genetic and environmental factors in the development of allergies in Canada?
JY: Our study highlighted the unique opportunity to investigate allergies in migrant populations, who are going through a natural experiment, in which the environment around them changed dramatically in a relatively short period of time.
By using this data, we saw that immigrants’ rates of non-food allergies increased the longer they were in Canada.
This tells us that environmental factors are carrying more weight in the development of allergic conditions in Canada. These factors could be things like air pollution, levels of sanitization and dietary choices, but we would need to do more research to pinpoint what those factors are.