The Ontario Health Study Newsletter, November 2025
Nov 7, 2025 // OHS Newsletter
In this issue:
• Final months to provide a health update
• 175,000 OHS participants contributed to novel study on heart disease risk
• Join your fellow participants at the CanPath Participant Town Hall
• Collection of second blood samples begins
• Cancer blood test prototype could one day be a game-changer
• Can we reach you?
• OHS participants will join Canada’s largest study on diet and physical activity
• Why do you remain a member of the Ontario Health Study?
Final months to provide a health update
Data from 26,600 questionnaires completed and securely stored, more participants needed!
We need your health update. With only four months to go the OHS has collected 26,600 complete questionnaires. We need 23,400 more by the end of March 2026 when the questionnaire closes. We need to gear up for other Study activities, such as the HEALthy Eating and Supportive Environments (HEAL) Study that you can read more about in this newsletter.
The Follow-Up Questionnaire 2 is important because it collects similar data at multiple timepoints, which allows researchers to track how participants’ health changes over time, evaluate screening programs, and identify “hot spots” where certain conditions are more common than elsewhere in the province. Seems too personal? The study design ensures these changes can be tracked without ever providing any information to researchers that would personally identify you.
There are also new sections to complete that focus on your mental health and wellbeing, as well as your access to healthcare. In just 30 minutes you can help to both broaden and deepen the OHS platform as a launching point for cutting-edge research.
If you haven’t done so, your questionnaire is ready to complete on your OHS account.
OHS Pop Quiz:Does Ontario Health (the provincial healthcare ministry) see your responses to the OHS Follow Up Questionnaire 2? |
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175,000 OHS participants contributed to novel study on heart disease risk
Women may benefit more from early lifestyle changes than previously thought
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Looking at eight common health behaviors and factors associated with cardiovascular disease, do men and women face the same level of risk? The answer is no; women appear to face a greater risk than men with a similar heart-health profile. That was the finding of a recent study that reviewed 11 years of data from 175,000 OHS participants. “We found that cardiovascular health status appeared to have a stronger impact on future events in women than in men,” said Dr Maneesh Sud, a cardiologist and clinician scientist at Sunnybrook Health Sciences Centre in Toronto and the study's lead author. |
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| Dr. Maneesh Sud (Photo by Kevin Van Paassen/Sunnybrook) |
Dr. Sud’s team looked at the following factors:
Modifiable behaviours: |
Health factors: |
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Physical Activity |
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Obesity |
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Diet |
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Blood glucose levels |
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Sleep |
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Blood cholesterol levels |
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Smoking |
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Blood pressure |
The study authors characterized a group of 175,198 OHS participants (61.4% women) into three categories of cardiovascular health: Ideal, Intermediate or Poor.
Here’s what they found:
- More women (9.1%) had ideal cardiovascular health compared to men (4.6%)
- Less than 1 in 10 women OR men achieved ideal cardio health.
- Fewer women had poor cardiovascular health (21.9%) compared to men (30.5%)
- Despite this, as cardiovascular health status declined, the relative impact on the future rate of cardiovascular disease was greater for women than for men.
- Poor health was associated with a 5-times higher rate of heart-health related events in women, compared to a 2.5 times higher rate of cardiovascular disease events in men (as compared to those with ideal health)
- The findings highlight the importance of considering sex-specific health promotion strategies to help keep women and men healthier longer.
Who they studied:
The team looked at data from 175,098 OHS participants who
- Completed the OHS baseline questionnaire between September 2009 and December 2017
- Had no previous history of heart attacks, stroke, congestive heart failure, metastatic cancer, liver disease, chronic dialysis or dementia and other conditions.
The takeaways
“This study was novel, in that we were one of the first groups in Canada to evaluate the impact of newer cardiovascular measures such as sleep, diet, and activities,” said Dr. Dennis Ko, Senior Scientist at Sunnybrook and the Primary Investigator for the OHS-powered research project.
More research is needed, but Dr. Ko said the study suggests that women may benefit more from early lifestyle interventions than previously thought.
"A healthy lifestyle is key to preventing heart attacks, strokes, and protecting cardiovascular health, which is all the more reason to proactively take a few steps to improve your health habits. Move more, eat a healthy diet, quit smoking and try to get good night’s sleep.”
Read Dr. Sud’s paper in the journal JACC: Advances for the deep dive on his team’s work.
Join your fellow participants at the CanPath Participant Town Hall
Canada-wide event goes live online November 17 2025
Maybe you know that the Ontario Health Study is one of the seven regional cohorts that make up CanPath: the Canadian Partnership for Tomorrow’s Health.
CanPath will soon host its second nationwide Participant Town Hall, which will allow participants from across the country to ask questions, learn more about upcoming questionnaires like the HEAL Study, and hear about plans for it’s recent-$3 million operating grant from the Canadian Institutes of Health Research (CIHR) to tackle pandemics, rising rates of early-onset cancers, and health risk factors related to the climate.
Attendees will hear directly from CanPath’s scientific leaders how the questionnaire data and biosamples collected over the years have been contributing to made-in-Canada research for the past 16 years, helping to uncover new findings in cancer prevention.
The Town Hall, titled “Preventing Cancer, Together: How your data is driving discoveries,” takes place online from 12-1:30pm ET on Monday, November 17, 2025. A recording of the event will also be shared on YouTube.
Register for the town hall and submit your questions here
Collection of second blood samples begins
Invitations roll out to a subset of participants
After a small group of pilot invitations began in September, the OHS is now inviting selected participants to provide an additional blood sample.
A total of 3,000 blood samples will be collected from among the roughly 40,000 participants who previously provided a blood sample to the OHS. If you are selected for a second blood sample, we will send you an email request to take part. We will analyze your sample, and within a few weeks of your visiting a lab we will give you back a blood analysis report with results from up to 15 different tests.
Much like completing Follow-Up Questionnaires over time, having blood samples from multiple time points provides researchers with a unique opportunity to track health changes over time, as well as how your blood reflects these changes, by looking for “biomarkers” or other indicators present in your blood long before a diagnosis, which could lead to earlier detection or prevention of diseases like cancer.
Second Blood Collection Progress (as of Nov 3, 2025)
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358 Invited |
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226 Completed Screening |
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160 Kits Mailed |
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17 Reports Generated |
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Cancer blood test prototype could one day be a game-changer
OHS blood samples used to develop simple cancer check for common cancers
Imagine if a simple blood test could check for early signs of cancer – for several common cancers all at the same time. If that test came back positive for one or more, imagine the benefit if you could start treatment at a much earlier, easier-to-treat stage of the disease. And, zooming out: calculate the savings to the health care system if more cancers were detected, then treated, much earlier.
A biotech company thinks it has a promising model for that future multi-cancer blood test, and will use OHS participant blood samples to advance its latest prototype that looks for lung, colorectal and prostate cancers.
miRoncol Health has spent 5 years developing this multi-cancer blood detection test. The test looks for microRNA (miRNA) in the blood to detect early-stage cancers.
The OHS will provide blood samples from up to 2880 OHS participants who were cancer-free at the time they provided blood, had no prior history of cancer and remained cancer-free for 2 years. These samples will serve as miRoncol’s ‘control group’.
The Ontario Tumour Bank (OTB) will supply up to 2880 blood samples from individuals who are not OHS participants, but who previously provided OTB with cancerous tumour samples. The OTB is not affiliated with the OHS, but both are located at the Ontario Institute for Cancer Research in Toronto.
miRoncol will use OTB cancer blood samples and the OHS cancer-free blood samples to validate its latest prototype by performing microRNA sequencing on the provided lung, colorectal and prostate cancer blood samples. The company then hopes to use the results to help make it’s updated model into a cost-effective PCR-based assay or test.
Developing a low-cost, single blood test to check for multiple cancers would greatly benefit people at risk for cancers, especially in communities with limited resources, notes Christopher M. Gallagher, MD, Chief Medical Officer, miRoncol Health. Currently, cancer screening options are limited to only a few cancer types (breast, colon, cervix, and lung). Nearly 70% of cancer deaths occur in cancer types with no screening options.
Participant privacy is protected
The OHS blood samples will be de-identified, meaning miRoncol researchers will not be able to identify who provided the samples. The company is prohibited from sharing or disclosing the data or samples provided by the OHS, and any remaining samples will be destroyed or returned to the OHS.
Future researchers may benefit
As with all its data agreements with researchers, the OHS will receive back any ‘derived data’ – new data generated because of the research project – after an agreed-upon time period. This means the OHS will be able to make that additional data available to approved academic researchers, so that the broader scientific community may benefit.
Can we reach you?
Keep your email, phone and postal coordinates current
How can we share exciting new results or new activities to join if we can’t reach you? Sign in here to update your personal information
If any of your contact information changes, please update this info on your account to make sure we can still reach you in the future. Since April 2025, almost 3,000 of you provided an updated email address, so if this is the first time you’re seeing our newsletter in quite a while – welcome!
OHS participants will join Canada’s largest study on diet and physical activity
Help researchers explore how diet and activity are impacted by where we live
Get ready – In Spring 2026, the OHS will invite you to do several online questionnaires describing both what you eat, and your physical activities.
The new HEAL Study (HEALthy Eating and Supportive Environments study) will also explore aspects of your neighbourhood – like the type of food outlets close to you and how ‘walkable’ your area is.
Why is the HEAL Study important?
Poor diet and physical inactivity are among the top risk factors for cancer and chronic diseases in Canada. There is also strong evidence that where people live influences what they eat and how active they are.
To date, similar studies have been limited to just a few areas in Canada, specific populations and a small number of foods and activities.
This national study, open to 330,000 Canadians participating in regional health studies like the OHS, will help fill this knowledge gap.
What will I be asked to do?
HEAL is detailed, very detailed. In fact, it’s the biggest ask the OHS has ever made of our participants. You will be invited by email and asked to:
- Log in to your OHS account and take the HEAL questionnaire, providing information about your access to nutritious food, financial resources available for buying food, and general questions about your diet and physical activity.
- Two weeks later, fill out a questionnaire about your food intake and physical activity over the previous 24-hours. Two weeks after that, we’ll ask you to do the 24-hour food and activity recall questionnaire again. This will help capture the general patterns of your diet and activities.
- 11 months later, we will ask you to complete a questionnaire about your food intake and physical activity over the previous year. This look backwards will help capture special events and seasonal changes in what you eat and how you move.
What happens if I choose not to participate or opt out early?
The HEAL Study is completely voluntary. You may opt out of HEAL at any time, and you will remain a valued part of the Ontario Health Study.
Register for a November 17 webinar and learn more about the HEAL study
Why do you remain a member of the Ontario Health Study?
Nanett from York Region has been contributing to the Ontario Health Study for 14 years. Here’s what she had to say:
We love hearing from you. Why do you remain a member of the Ontario Health Study? Email us at info@ontariohealthstudy.ca