Death Knell For Fish Oil?

Image of fish oil capsule illustrating article about fish oil supplements


A new study published in the prestigious Annals of Internal Medicine has looked into the literature published to date and has come to the conclusion that the evidence to date does not support recommending the use of Omega 3 and 6 supplements whether as part of or in addition to a healthy diet. 

Fish oils, omega3 and omega 6 supplements and similar products are the most popular dietary supplement on the planet with worldwide sales set to tip NZD 40 billion in 2016, according to one forecast.  On a world scale, this may not seem much, but if the fish oil capsule industry were a country, it would rank about 88th in the world, just above Bahrain and Jordan, neither of whom have a GDP above this level.

It all started when it was discovered that people who ate a lot of fish as part of their diet had a lower than expected rate of heart disease.  Eventually it was discovered that not all fats are equal. 

Saturated fats such as are found in large quantities in red meat, eggs and dairy products are now known to be far more atherogenic (cause more heart disease) than polyunsaturated fats which are more commonly found in fish and vegetable sources.  Numerous studies have shown that people who eat fewer saturated fats by and large get less heart disease and also that these people tend to consume more polyunsaturated fats.  This led to the suggestion that perhaps consuming more polyunsaturated fats would reduce heart disease, though a moment more thought shows that though this might be possible, it is not proven by the earlier statements.

The new paper performed two very careful analyses:

  1. Comparison of polyunsaturated fat intake was completed across 32 observational studies where patients reported their diet (530,525 patients) and17 studies where biomarkers were used to assess actual polyunsaturated fat intake (25,721 patients).  For all of the measured fatty acids, no significant difference could be shown between those with the highest intake or levels and those with the lowest. 
  2. Comparison of supplements against placebo in 27 trials (103,052 patients) showed no significant difference.

This is of course a meta-analysis and is not as good as a single well-conducted trial with the same number of patients, but it would be fair to say that there is absolutely solid evidence that dietary polyunsaturates do not reduce the risk of heart disease.  This can be deduced from the fact that the studies had very similar no-difference outcomes.

The really important thing to note here is that this is a study looking primarily at 'hard endpoints' - that is to say heart attacks and strokes, the things we actually want to prevent rather than markers of risk such as lipid levels.   This makes it a particularly valuable piece of research in terms of how we should advise patients.

As for supplements, they are almost certainly just an expensive placebo.  Harmless, but certainly a waste of money.  Whilst some small scale studies have suggested benefit and are included in this larger analysis, the overwhelming majority of well-conducted trials show supplements of this type do not reduce your risk of heart disease. 

For those seeking heart health, all is not lost.  Whilst supplements are provably useless, a healthy plate diet has ample evidence to support it overall, even if the individual parts are still being debated. 



Capsule image:  Health Guage

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