Fish oil supplements have had a long and controversial history. There was a lot of inconsistency in the research around supplementation and several organizations only added to this confusion. The incomplete reporting by media outlets have also added to this confusion.
Here, I’ll give a brief timeline of the evidence for fish oil and CVD outcomes.
1970s | A group of explorers noticed that people who consumed fish also had lower incidences of heart disease.
2002 | The American Heart Association put out a statement suggesting that fish oil supplementation was beneficial for fatal outcomes.
2016 | The American Heart Association creates a scientific advisory group to look at all the evidence and concludes that despite the controversy, there was a small benefit from fish oil and it could be worth it for people who had a history of CVD events.
2018 | Large meta-analysis published in JAMA with 77,000 + participants found no statistically significant benefit from fish oil supplementation on real clinical endpoints.
Let’s look at the evidence from the recent JAMA meta-analysis.
nonfatal heart attacks
major vascular events
Must be a randomized controlled trial
Studies must have a minimum of 500 participants
Studies must be at least one year long
Studies must use fish oil supplements
Characteristics of Included Studies
10 randomized trials included
8 are double-blind, 2 are open label.
Has a total of 77,000+ participants
Average age: 64 years
Average length of studies: 4.4 years
Used mainly up to 1 g/d of fish oil (ranges: 226 to 1800 mg/day of EPA and 0 to 1700 mg/day of DHA)
No statistically significant association between fish oil supplementation and any of the primary outcomes.
However, the compatibility (confidence) intervals suggest very small effects.
Up to a 7% decrease in the rate ratio is compatible with the test model.
No significant differences amongst individual trials (worth remembering that these are exploratory and the analyses could be underpowered. This should not be taken as evidence for no effect.)
No significant associations found with subgroup analyses (same point as above)
High statistical power/increased precision for the main primary outcome
Only included studies of long duration
Included studies were mostly at low risk of bias
Up to 1 g/d of fish oil may not have that much to offer when it comes to preventing CVD events in individuals who have a history of CVD. More research is currently underway on higher doses of fish oil supplementation, and there might be some promise there.