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 widely promoted globally because of a common belief that it will protect against heart disease.
There is more than one possible mechanism for how they might help prevent heart disease, including reducing blood pressure or reducing cholesterol.
Omega-3 fats are available as over-the-counter supplements and they are widely bought and used.
A new Cochrane systematic review, published on July 18, 2018, in the Cochrane Library, combines the results of 79 randomised trials involving 112,059 people.
These studies assessed the effects of consuming additional omega-3 fat, compared to usual or lower omega-3 consumption, on diseases of the heart and circulation.
Twenty-five studies were assessed as highly 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 investigated 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 ALA trials 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 Cochrane researchers found that increasing omega-3 provides little, if any, benefit on most outcomes that they looked at.
They found high-certainty evidence that long-chain omega-3 fats had little or no meaningful effect on the risk of death from any cause.
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 omega-3 fats (including EPA and DHA), primarily through supplements, probably makes little or no difference to risk of cardiovascular events, coronary heart deaths, coronary heart disease events, stroke or heart irregularities.
The systematic review suggests that eating more ALA 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%.
Source: The Star