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.
The prevalence of allergic conditions has been
increasing worldwide, with the highest rates seen in
Western countries like Canada. The development of
allergies is known to be related to both genetic and
environmental factors, but the causal pathways
remain unclear. Studies on immigrants provide a
unique opportunity to disentangle these two factors
and provide a better understanding of the disease
By analyzing data collected in the Canadian
Community Health Survey, researchers 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.
Researchers 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, scientists wanted to
know if that was also true in Canada.
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. Itís
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?
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
This 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, researchers saw that immigrantsí
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
scientists would need to do more research to
pinpoint what those factors are.
For more information
Can J Public Health
Prevalence of non-food allergies among
non-immigrants, long-time immigrants and recent
immigrants in Canada
The University of British Columbia - UBC