About the Study

What is the Ontario Health Study (OHS)?

The Ontario Health Study is an ongoing research study investigating risk factors that cause diseases like cancer, diabetes, heart disease, asthma and Alzheimer’s. Between 2009 and 2017, the OHS recruited over 225,000 Ontario residents over the age of 18 to complete health-related questionnaires online, with follow-up questionnaires administered over time to follow their health as they age. Researchers will use this health information to study how our lifestyle, environment and family history affect our health over time and to develop strategies for the prevention, early detection and treatment of diseases. The Ontario Health Study also collected over 41,000 blood samples. The measurements and samples collected will help researchers better understand the factors that influence our health and quality of life.

Is this a government study?

No. Currently, more than 320 senior scientists and clinicians at universities, hospitals and research institutes across Ontario collaborated in the development of the Study and the design of its online health questionnaires. Their areas of expertise include: heart disease and stroke, obesity and diabetes, respiratory health, aging, hearing, nutrition, mental health, vision, neurology, dentistry and the effect of the environment on health.

Who is funding the Ontario Health Study?

The not-for-profit Study is funded by four organizations: the Ontario Institute for Cancer Research, Cancer Care Ontario, Public Health Ontario and the Canadian Partnership Against Cancer.

Why is the Study focused on Ontario?

Ontario is an excellent location for such a large, long-term health population study. Not only do Study participants reflect the province’s rich diversity, but the province is home to some of the most talented cancer and chronic disease researchers anywhere. The Ontario Health Study is also part of an important national research platform, the Canadian Partnership for Tomorrow Project. Health data from more than 165,000 of the 225,000 participants of the Ontario Health Study have been made available to the CPTP, which stands among the largest population cohorts in the world, and is made up of five regional health studies across Canada.

The Partnership is also supporting the formation of a sixth cohort in Manitoba to expand the depth of CPTP’s national dataset and biological assets.


Will the information I provide really make a difference?

Similar studies have led to important discoveries in the past. For instance, the Framingham Heart Study in the United States, which began in 1948 and continues today, led to the discovery in 1960 that cigarette smoking increases the risk of heart disease. In fact, much of what we understand today about the causes of common diseases comes from health studies of the general population. What sets the Ontario Health Study apart from other studies is its potential to reach a large and diverse population residing in Ontario. With it being possible to follow the health of so many diverse people, the Study may detect new risk factors or combinations of risk factors and may be able to investigate many less common diseases. The OHS will also take advantage of the opportunity to link to many valuable sources of information that are unique to Ontario, such as the Ontario Cancer Registry. Some of the best-linked health data in the world – collected for routine administrative purposes – exists in Ontario.