A new Cochrane review has found the evidence to support omega-3 supplements is not as strong as is often stated

There is little or no effect of omega-3 supplements on our risk of experiencing heart disease, stroke or death, a comprehensive Cochrane review has found.

Increased consumption of omega-3 fats is widely promoted globally because of a common belief that 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 readily available as over-the-counter supplements and they are widely bought and used.

The review combined the results of 79 randomised trials involving 112,059 people.

These trials 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 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 long-chain omega-3 provides little if any benefit on most outcomes they examined.

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 long-chain 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.

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 researchers collected information on harms from the studies, but information on bleeding and blood clots was very limited.

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%.

The review team found that reductions in cardiovascular events with ALA were so small that about 1000 people would need to increase consumption of ALA for one of them to benefit.

Similar results were found for cardiovascular death. They did not find enough data from the studies to be able to measure the risk of bleeding or blood clots from using ALA.

Increasing long-chain omega-3 or ALA probably does not affect body weight or fatness.

Following publication of the review, the Dietitians Association of Australia has encouraged Australians to review their diet.

The study reinforces that it’s more important to focus on what we are serving up on our dinner plate than to buy supplements, it says.

“Omega-3s play a role in eye, skin and heart health as well as brain function, fertility and pregnancy,” said spokesperson for the DAA, Natasha Murray.

“Incorporating foods such as oily fish, seafood, plant-based oils and nuts and seeds are a way to help you boost your dietary intake of omega 3.”

However, Ms Murray cautions about becoming too focused on one nutrient.

“At the end of the day, diet quality and variety is key. By consuming a wide range of whole foods, it allows us to gain a variety of nutrients, setting us on the path to good health,” she said.