Nathan Denette / The Canadian Press
Dietary guidelines have long recommended eating fish twice a week, especially fish rich in omega-3 fatty acids, to help prevent heart disease.
However, according to new data from Health Canada, many of us are ignoring this advice.
The study, published in the American Journal of Clinical Nutrition this April, found that four in ten Canadians have blood omega-3 levels, which is linked to a high risk of coronary heart disease.
According to the researchers, to get into the low-risk zone would have to eat significantly more fish than current dietary guidelines recommend.
Omega-3 Fats and Heart Health
Oily fish (e.g. salmon, sardines, trout, mackerel, herring, tuna) are good sources of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) blood vessel function and lower blood triglycerides (fats).
Since the body cannot make EPA and DHA on its own, eating fish and taking supplements are the only ways to increase the levels of omega-3s in the body.
Observational studies have consistently linked higher uptake and higher blood levels of EPA and DHA with lower risk of coronary artery disease, myocardial infarction, and cardiovascular death.
Two recent analyzes of randomized controlled trials found that omega-3 (EPA and DHA) supplementation provided significant protection against coronary artery disease, myocardial infarction and death from cardiovascular disease, especially in high-risk populations (e.g., people with established Cardiovascular disease or diabetes). .
Omega-3 status of Canadians
To determine omega-3 levels in Canadians, Health Canada researchers analyzed data from 4,025 adults aged 20 to 79 who participated in the Canadian Health Intervention Survey from 2012 to 2015.
The Ongoing Canadian Health Action Survey collects health, lifestyle information and physical measurements from Canadians to improve health programs and services.
The Omega-3 Index (OI) is a measure of the amount of EPA and DHA in red blood cell membranes. It is expressed as a percentage of the total amount of fatty acids present.
An OI of less than 4 percent is considered to be a high risk for coronary heart disease, 4 to 8 percent as a medium risk and over 8 percent as optimal or cardioprotective.
The average Canadian adult had an OI of 4.5 percent, indicating medium risk. Almost 40 percent of Canadians were in the high risk category and only 2 percent had omega-3 levels in the optimal range.
How Much Omega-3?
According to an editorial in the same issue of the magazine, the average Canadian with an OI of at least 8 percent could experience 30 percent fewer premature cardiovascular deaths. But is that a realistic goal?
According to the researchers, a daily dose of 1,500 mg of EPA and DHA (combined) is required to go from 4 percent OI to 8 percent over a period of three months.
To do this, you need to eat at least 5 1/2 servings (6 ounces each) of fatty fish per week, much more than the two servings recommended by the Heart and Stroke Foundation of Canada.
Such a dose of EPA and DHA could also be achieved through daily intake of a highly potent omega-3 supplement (which would limit the risk of consuming too much mercury from fish) or through a combination of fish and dietary supplements.
Perhaps a feasible public health goal, according to the editorial, would be for almost all Canadians to achieve an OI greater than 4 percent. This is likely possible by consuming fatty fish twice a week.
Healthcare professionals could then help people at high risk for low-OI cardiovascular disease achieve optimal OI through diet and supplements.
Setting a recommended daily allowance for EPA and DHA as we have for vitamins and minerals could help Canadians consume more omega-3 fats. Given the vast amount of evidence linking omega-3 fats to cardiovascular health over the past two decades, some scientists claim this is strongly justified.
Other strategies to help Canadians improve their omega-3 status could include labeling fish and fortified foods high in EPA and DHA, fortifying more foods with EPA and DHA, and increasing fish intake.
All food for thought.
Leslie Beck, a Toronto-based nutritionist, is the director of food and nutrition for Medcan. Follow her on Twitter @LeslieBeckRD
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