A major health study underway in Ontario could have far-reaching benefits as researchers investigate risk factors for common diseases such as cancer, heart disease and diabetes.

The Ontario Health Study runs over the course of each participant's entire life, charting how chronic diseases grow and evolve, with the ultimate aim of preventing the diseases entirely.

It is believed that the breadth of the study could make it one of the most important health research projects in the world.

"The study is to help understand those diseases. It is to understand how to best treat those diseases, who will respond best to treatments. And ultimately it is to prevent those diseases," Prof. Lyle Palmer, executive scientific director of the Ontario Health Study, told CTV's Canada AM on Monday.

The Ontario Health Study is considered the largest health study of its kind in Canadian history.

Almost 200,000 people have joined the study since it was first announced in 2010, and more than 320 scientists and clinicians are participating in the research study.

Anyone over the age of 18 can sign up at the Ontario Health Study website and answer a primary questionnaire that takes about half an hour. Participants are contacted once a year to update their information and answer a series of follow-up questions.

"This study is designed go forever. That way we can see the development of chronic disease over the lifetime of the individual and ultimately work out where we can intervene to change that trajectory of human disease," Palmer said.

Palmer says the study will have a major national and international impact. Because of Ontario's large and diverse population, the results are expected to hold relevance across North America and the world.

"There is enormous ethnic and cultural diversity in Ontario," Palmer said. "There are 13.5 million people in Ontario so there is a very large population to draw from, and we have some of the best-linked medical administrative data in the world. Everything is set up for success here."