The seafood counter is shown at a Loblaws store in Toronto on May 3, 2018.Nathan Denette/The Canadian Press
Dietary guidelines have long recommended eating fish, especially fish rich in omega-3′s, twice a week to help prevent heart disease.
Yet, according to new data from Health Canada, many of us aren’t heeding this advice.
The study, published this April in the American Journal of Clinical Nutrition, revealed that four out of 10 Canadians have an omega-3 blood level that’s associated with a high risk of coronary heart disease.
Moving into the low risk zone, the researchers say, would require eating considerably more fish than current dietary guidelines advise.
Omega-3 fats and heart health
Oily fish (e.g., salmon, sardines, trout, mackerel, herring, albacore tuna) are good sources of EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid), omega-3 fatty acids shown to reduce inflammation, prevent abnormal heart beats, improve blood vessel function and lower blood triglycerides (fats).
Since the body can’t make EPA and DHA on its own, eating fish and taking supplements are the only ways to increase omega-3′s in the body.
Observational studies have consistently tied higher intakes and higher blood levels of EPA and DHA to a lower risk of coronary heart disease, heart attack and cardiovascular death.
Two recent analyses of randomized controlled trials found that omega-3 supplementation (EPA and DHA) provided significant protection from coronary heart disease, heart attack and death from cardiovascular disease, particularly 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 Measures Survey from 2012 to 2015.
The continuing Canadian Health Measures Survey collects health and lifestyle information and physical measurements from Canadians for the purpose of improving 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’s expressed as a percentage of the total amount of fatty acids present.
An OI of less than 4 per cent is considered high risk for coronary heart disease, 4 to 8 per cent is intermediate risk and over 8 per cent is optimal or cardioprotective.
The average Canadian adult had an OI of 4.5 per cent, indicating intermediate risk. Almost 40 per cent of Canadians were in the high risk category and only 2 per cent had omega-3 levels in the optimal range.
How much omega-3?
According to an editorial in the same issue of the journal, if the average Canadian had an OI of at least 8 per cent, there could be 30 per cent fewer premature cardiovascular deaths. But is this a realistic goal?
According to the researchers, it takes a daily dose of 1,500 mg EPA and DHA (combined) to go from an OI of 4 per cent to 8 per cent over three months.
To do so means eating at least 5 1/2 servings (six ounces each) of oily fish a week, a lot more than the two servings recommended by the Heart and Stroke Foundation of Canada.
Such an EPA and DHA dose could also be achieved by taking a high potency omega-3 supplement each day (which would limit the risk of consuming too much mercury from fish), or through a combination of fish and supplements.
Perhaps a more feasible public health goal, according to the editorial, would be to have almost all Canadians achieve an OI of more than 4 per cent. This is likely doable by eating oily fish twice a week.
Health care professionals could then help people at high risk of cardiovascular disease who have a low OI achieve an optimal OI through diet and supplements.
Establishing a recommended daily intake for EPA and DHA, like we have for vitamins and minerals, could help Canadians consume more omega-3 fats. Given substantial evidence over the past two decades connecting omega-3 fats to cardiovascular health, some scientists contend there is strong justification to do so.
Other strategies to help Canadians increase their omega-3 status could include labelling fish and fortified foods with EPA and DHA content, fortifying more foods with EPA and DHA, and stronger promotion of fish intake.
All food for thought.
Leslie Beck, a Toronto-based private practice dietitian, is director of food and nutrition at Medcan. Follow her on Twitter @LeslieBeckRD
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