The ‘Healthy Immigrant Effect’ Is Alive and Well in Kidney Disease, Study Finds

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Immigrants generally have worse social determinants of health, like income and education, than nonimmigrants. On the other hand, they benefit from the “healthy immigrant effect,” which has been linked to healthier lifestyle behaviors such as increased physical activity, diets containing more fruits and vegetables and less highly processed foods, lower smoking rates and consumption of alcohol.

Which is more important for kidney health?

If it’s social determinants, immigrants would tend to develop less healthy kidneys. If it’s lifestyle behaviors, the protective healthy immigrant effect might extend to kidney disease.

The answer, according to a study involving most adult residents of the Canadian province of Ontario, is clear: the healthy immigrant effect is dominant, although less so for refugees, who make up 17% of immigrants to Canada and are likely to arrive in poorer health.

Canada has among the highest immigration rates in the world, with 20-25% of the population foreign-born. It also has universal health insurance, which minimizes access to care as a barrier compared to other nations.

The study, published March 26, 2025, in Kidney International, examined Ontario medical records for kidney function and histories of dialysis and kidney transplantation for 2.3 million immigrants and 8.2 million native-born Canadians, following them for a median of more than eight years.

Among the key findings: Immigrants had a 27% reduced likelihood of kidney function decline and 12% reduced odds of kidney failure compared with nonimmigrants. Refugees also were better off than native-born Canadians. Within the immigrant cohort, however, refugees had a 21% higher likelihood of kidney function decline and a 27% greater likelihood of kidney failure compared with nonrefugees.

Region of origin also made a difference. Although the researchers measured a 10% reduced likelihood of kidney function decline among immigrants from elsewhere in North America — those presumably most similar to the native-born — the reduction was progressively higher for immigrants from Africa (12%), South America (14%), the Middle East (18%), Europe (25%) and Asia (37%).

Interestingly, while studies of other chronic medical conditions have found that the healthy immigrant effect wanes over time, the kidney study found no difference in the effect among those who landed within the previous five years compared with those who arrived longer ago.

Most of the 10-member research team is affiliated with institutions in Ottawa and Toronto, and two are listed as co-senior authors: Manish M. Sood, M.D., M.Sc., a professor of medicine at the University of Ottawa, senior scientist at the Ottawa Hospital Research Institute and a staff nephrologist at the hospital, all in Ottawa, Ontario, and Gregory L. Hundemer, M.D., M.P.H., an assistant professor of medicine at the university with identical appointments at the hospital and its research institute, who is also the hospital's Lorna Jocelyn Wood Chair for Kidney Research and an adjunct scientist in the ICES Kidney, Dialysis and Transplantation Research Program, also in Ottawa.

“The findings from this study suggest that policies to support maintaining these beneficial lifestyle behaviors among immigrants upon landing in their new country should be promoted,” the authors write, adding that “the immigration process itself may further contribute to the healthy immigrant effect” for reasons ranging from healthier individuals being more likely to pursue (and to pass medical screenings required for) immigration, to immigration processes in Canada and other countries placing a high value on factors such as education level and language skills, “social factors which not only promote successful employment post-immigration, but also are linked to improved kidney (and overall) long-term health.”