Australians have a huge appetite for fish oil supplements, but a new review suggests that taking them does not protect against cardiovascular disease, at least in high risk patients.

A new meta-analysis of 10 large randomised controlled trials has found that taking omega 3 fatty acid supplements (containing long-chain fatty acids EPA and DHA) had no significant associations with coronary heart disease death, non-fatal myocardial infarction or any coronary heart disease events.

The Oxford University study, which investigated the outcomes of 78,000 high-risk patients (two thirds had a history of CHD, 28% had a prior stroke) over a mean period of 4.4 years, found supplementation also had no significant association with major vascular events.

No protective effect of omega 3 supplements was seen in subgroups including people with prior coronary heart disease, diabetes or hyperlidaemia.

Writing in JAMA Cardiology, the review authors note that current American Heart Association guidelines advise that the use of omega-3 fatty acids “is probably justified” in individuals with prior CHD.

However they conclude that the meta-analysis provides “no support for the recommendations to use 1 g/d of omega-3 FA in patients with a history of CHD for the prevention of CHD, non-fatal MI or any other vascular events”.

“Results of the ongoing trials are needed to assess if higher doses of omega-3 FAs (3-4 g/d) may have significant effects on risk of major vascular events”, they add.

Supplements retailing in Australia typically contain 1000 mg of fish oil, equivalent to 300-500mg omega-3 triglycerides. Sales are estimated to be worth over $200 million a year, with expenditure growing at a rate of more than 10% per year, according to a 2013 article by CHOICE.

Heart Foundation chief medical advisor Professor Garry Jennings said the conclusion drawn in the meta-analysis “aligns with the Heart Foundation’s current position that the evidence has changed for omega-3 supplements”.

“We do not advise routine recommendation of omega-3 supplements for heart health by health professionals (and) we do recommend health professionals consider the use of omega-3 supplements for those with high triglyceride levels and as an additional treatment for heart failure”, he said.

The Heart Foundation recommends people eat fish regularly to maintain good cardiovascular health.

Commenting on the findings, Professor Craig Anderson, Professor of Neurology and Epidemiology in the Faculty of Medicine, University of NSW, said the study’s findings were “not too surprising”.

“Use of fish oils is widely promoted as having magic health benefits but the science to support this based on the highest levels of research are very limited,” said Professor Anderson, who is also executive director of the George Institute in China.

“One to three tablets of fish oils has no effect on lipid levels, coagulation or platelet function, and the fish oil loses potency through natural oxygenation within a few months after opening the cap (hence, fish oil smell)” he said.

There was evidence to support use of up to 20 fish oil tablets per day for modification of lipid levels, he added, But statins and other drug treatments were simpler and more effective.