Recent immigrants tend to be healthier and die less frequently than their Canada-born counterparts, a new study confirms.

But the report from Statistics Canada also shows that this so-called "healthy immigrant effect" generally diminishes the longer a person has lived inside the country.

By combing through census data and death certificates collected between 1991 and 2001, the study's author Edward Ng was able to compare the mortality rates of Canadian residents born inside and outside the country. Of the immigrants surveyed, his results show that an average of 1,006 men and 610 women die every year per 100,000 people. These figures are significantly lower than those found for Canadian-born adults -- 1,305 and 731 for men and women respectively.

While Ng says the focus of the study is to present the data and not to draw any conclusions, he posits that part of health gap between immigrants and Canada-born citizens can be explained by immigration policy itself.

"There is a strict medical screening process for new immigrants," says Ng. In other words, the group of people allowed to enter the country under Canadian immigration policy are, as a group, healthier than the average native-born Canadian.

"But there's also a self-selection effect," says Ng. "If someone is sick, it's just not as easy to emigrate."

Distinguishing between "recent," "medium-term," and "established" immigrants, the study also found that newer arrivals (those who had moved to Canada after 1981) were generally healthier than those immigrant who had been residing in Canada for a longer period of time. This finding was made after adjusting the data for health effects relating to age differences.

"This could be the result of different lifestyle factors," says Ng. For example, obesity rates among new immigrants are far below the national average but climb upward the longer a person lives inside the country, he says.

The study was based on the data of over 2.7 million adults over the age of 25.

Ben Christopher reports for The Tyee.