Evidence for protective effect of fish oil not conclusive

December 24, 2008

Fish oil protects against deaths from heart problems, but doesn't provide a clear benefit in heart rhythm problems (arrhythmias), according a study published on bmj.com today.

More funding is urgently needed in this neglected area of nutrient research, say the authors of an accompanying editorial.

Consuming oily fish at least two to four times a week is recommended for patients after a heart attack. But the evidence for the protective effect of fish oil supplements is based on one large trial from over 10 years ago. More recent trials have showed no beneficial effect of fish oil on patient outcomes.

In an attempt to resolve the uncertainty, Professor Ross Tsuyuki and colleagues from Canada systematically reviewed randomised trials of fish oil as a dietary supplement in the prevention of cardiac deaths and arrhythmias (abnormal electrical activity in the heart that can lead to death), in more than 30,000 participants in 12 studies.

Fish oil was found to be effective at reducing deaths from heart problems, but showed no strong evidence of a beneficial effect on arrhythmias or deaths from all causes.

Three of the studies involving over 11,000 participants analysed the effect of fish oil supplementation on the reduction in implantable cardiac defibrillator interventions and reported a neutral effect. Six studies of over 31, 000 patients examined the effect of fish oil on sudden cardiac death and showed no benefit. A further 11 studies showed a 20% reduction in deaths from heart problems.

Interestingly, no evidence was found for a dose-response effect between type of fish oil and reduction in deaths from heart problems, so it was not possible for the researchers to suggest an optimal dose or formulation of fish oil.

In the accompanying editorial, Dr Eric Brunner and Professor Hiroyasu Iso say that the review emphasises the lack of available high quality evidence and the neglect of this important area of nutrient research.

They call for increased funding to resolve the uncertainty surrounding the protective effect of fish oil, to help the millions of people with heart disease and to protect the world's marine life—which, they say, is facing extinction for commercial gain, partly, and maybe unnecessarily, in the name of public health.

Source: British Medical Journal

Explore further: Best of Last Week – New definition of time crystals, new images of Pluto and the mechanism that causes neuropathic pain

Related Stories

Justices seem divided over EPA mercury limits (Update)

March 25, 2015

The Supreme Court's conservative justices cast doubt Wednesday on the Obama administration's first-ever regulations aimed at reducing power plant emissions of mercury and other hazardous air pollutants that contribute to ...

Reaching across the sea for the sake of water

January 9, 2015

The Arava desert, a salty wasteland dotted with tufts of scrub, gets only about an inch of rain each year. And yet cows lazily low at dairy farms that collectively produce nearly 8 million gallons of milk annually. Orange ...

Scientists discover mechanism of crude oil heart toxicity

February 13, 2014

Scientists from Stanford University and the National Oceanic and Atmospheric Administration (NOAA) have discovered that crude oil interferes with fish heart cells. The toxic consequence is a slowed heart rate, reduced cardiac ...

Energy innovation into a headwind

September 10, 2013

The public authorities in Japan are putting all their efforts into establishing a new industry based on floating offshore wind turbines. In Norway we have already developed the technology they need. So researchers are asking ...

Recommended for you

How the finch changes its tune

August 3, 2015

Like top musicians, songbirds train from a young age to weed out errors and trim variability from their songs, ultimately becoming consistent and reliable performers. But as with human musicians, even the best are not machines. ...

Machine Translates Thoughts into Speech in Real Time

December 21, 2009

(PhysOrg.com) -- By implanting an electrode into the brain of a person with locked-in syndrome, scientists have demonstrated how to wirelessly transmit neural signals to a speech synthesizer. The "thought-to-speech" process ...

1 comment

Adjust slider to filter visible comments by rank

Display comments: newest first

3 / 5 (2) Dec 25, 2008
Nice of the headline to mention arrhythmias, as otherwise I would have incorrectly assumed it was referring to ALL of fish oil's protective effects.

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.