In a new study, researchers find that there is little or no effect of omega 3 supplements on our risk of experiencing heart disease, stroke or death.
Omega 3 is a type of fat. Small amounts of omega 3 fats are essential for good health, and they can be found in the food that we eat.
The main types of omega 3 fatty acids are; alphalinolenic acid (ALA), eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA).
ALA is normally found in fats from plant foods, such as nuts and seeds (walnuts and rapeseed are rich sources).
EPA and DHA, collectively called long chain omega 3 fats, are naturally found in fatty fish, such as salmon and fish oils including cod liver oil.
Increased consumption of omega 3 fats is popular globally because of a common belief that that it will protect against heart disease.
There is more than one possible reason for how they might help prevent heart disease, including reducing blood pressure or reducing cholesterol.
Omega 3 fats are readily available as over-the-counter supplements and they are widely bought and used.
In the new study, researchers conducted a systematic review and combined the results of seventy-nine studies involving 112,059 people.
These studies assessed effects of consuming additional omega 3 fat, compared to usual or lower omega 3, on diseases of the heart and circulation.
Twenty-five studies were trustworthy because they were well designed and conducted.
The studies recruited men and women, some healthy and others with existing illnesses from North America, Europe, Australia and Asia.
Participants were randomly assigned to increase their omega 3 fats or to maintain their usual intake of fat for at least a year.
Most studies examined the impact of giving a long-chain omega 3 supplement in a capsule form and compared it to a dummy pill. Only a few assessed whole fish intake.
Most studies about omega3 ALA added omega 3 fats to foods such as margarine and gave these enriched foods, or naturally ALA-rich foods such as walnuts, to people in the intervention groups, and usual (non-enriched) foods to other participants.
The researchers found that increasing long-chain omega 3 provides little if any benefit on most outcomes that they looked at.
The risk of death from any cause was 8.8% in people who had increased their intake of omega 3 fats, compared with 9% in people in the control groups.
They also found that taking more long-chain omega 3 fats (including EPA and DHA) makes little or no difference to risk of cardiovascular events, coronary heart deaths, coronary heart disease events, stroke or heart irregularities.
Long-chain omega 3 fats probably did reduce some blood fats, triglycerides and HDL cholesterol.
Reducing triglycerides is likely to be protective of heart diseases, but reducing HDL has the opposite effect.
The findings suggest that eating more omega-3 through food or supplements probably has little or no effect on cardiovascular deaths or deaths from any cause.
However, eating more ALA probably reduces the risk of heart irregularities from 3.3 to 2.6%.
Increasing long-chain omega 3 or ALA probably does not affect body weight or fatness.
The team suggests that this review which go against the popular belief that long-chain omega 3 supplements protect the heart.
The study is published in the Cochrane Library.
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