Heart benefit of fish oil remains unclear
Wednesday December 24th, 2008
By Jane Collingwood
Fish oil is widely thought to boost the health of the heart - but a new study questions this.
Professor Ross Tsuyuki and colleagues from the University of Alberta in Canada say the bulk of the evidence of a benefit comes from a trial ten years ago, and recent trials have found no clear benefit.
The team reviewed findings investigating the supplements docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) and abnormal electrical activity in the heart (arrhythmias) and sudden cardiac death.
Twelve studies were reviewed, with a total of 32,779 patients. In these studies, the supplements were effective at reducing deaths from heart problems, but no strong evidence was seen on arrhythmias or deaths from all causes.
On the website of the British Medical Journal, the team report that the dose-response relation for DHA and EPA on reduction in deaths from cardiac causes was not significant.
Overall, "fish oil supplements were associated with a significant drop in deaths from cardiac causes, but had no effect on arrhythmias or all-cause mortality. Fish oils are a heterogeneous product, and the optimal formulations for DHA and EPA remain unclear," they conclude.
On the basis of current evidence, the mechanism and size of any effect is uncertain, writes Dr Eric Brunner from University College London, UK, in an editorial. He says heart attack patients are advised to eat two to four portions of oily fish a week, or take supplements.
The review was inconclusive, he believes, because insufficient high quality evidence is available. It "highlights the neglect of an important area of research into nutrient health, and hopefully it will lead to increased investment in research to resolve the uncertainty", he adds.
Leon, H. et al. Effect of fish oil on arrhythmias and mortality: systematic review. The British Medical Journal, 2009;338:a2931.
Brunner, E. and Iso, H. Fish oil and secondary prevention of cardiovascular disease. The British Medical Journal, 2008;337:a2541.
Tags: Heart Health | North America | Nutrition & Healthy Eating
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