Fish oils & bleeding risk: Extensive review supports safety of supplements

By Stephen Daniells contact

- Last updated on GMT

© iStock/mphillips007
© iStock/mphillips007

Related tags: Fish oil, Omega-3 fatty acid

Concerns that fish oil supplements may increase the risk of bleeding – a potential concern for people undergoing surgery – are unfounded, according to a systematic review the scientific literature.

Interest in fish oil and omega-3 fatty acids has increased over the decades since Dr Jorn Dyerberg and his co-workers first reported the cardiovascular benefits of the fatty acids in the early 1970s. Dr Dyerberg also reported that the Greenlandic Inuit, the people they studied for those early reports, had significantly longer bleed times than the general Danish population. This has been extensively studied over the years, and there is debate around whether fish oil supplementation should be stopped prior to surgery.

A new systematic review, published in the Danish Medical Journal​, found that the overall body of science does not support any concerns around increased bleeding during or after surgery.

Data from 16 studies on patients undergoing surgery found that fish oil did not increase bleeding or blood transfusion.

This was despite data from 32 publications in healthy people that found that fish oil supplementation was associated with a reduction in platelet aggregation, which would extend the time needed to form blood clots and stop bleeding.

“As the biochemical effect of fish oil supplements in healthy subjects was not reflected in an increased bleeding risk during surgery, this systematic review does not support the need for discontinuation of fish oil supplements prior to surgery or other invasive procedures,”​ wrote the authors from the Centre for Haemophilia and Thrombosis at Aarhus University Hospital in Denmark.

“It’s time this issue is put to bed”

The review’s findings were welcomed by Harry Rice, PhD, VP of regulatory & scientific affairs for the Global Organization for EPA and DHA Omega-3s (GOED): “I applaud the authors for their herculean effort to review the available research on omega-3s and bleeding risk,”​ Dr Rice told us. “It's no surprise that it corroborates past reports that fish oil does not increase the risk of bleeding. It's particularly noteworthy that the authors report on two studies demonstrating a reduced need for RBC transfusions in surgical patients taking fish oil.  I think it's about time this issue is put to bed.”

Review details

Surgery bleeding © iStock beerkoff
The impact of fish oil supplementation on bleeding risk has been extensively studied. Image: © iStock/beerkoff

Scientists from surveyed the literature for studies reporting the effects of fish oil supplements on hemostasis and bleeding risk. Most of the studies reviewed were gold-standard randomized controlled trials or included a control group.

Studies in healthy people showed that, in general, fish oil supplements were associated with a reduction in platelet aggregation. Data from two studies showed that this platelet aggregation was normalized two and three months after stopping fish oil supplementation. “This suggests that primary hemostasis is affected by fish oil exposure beyond ten days, which is the average lifespan of platelets, after discontinuation,”​ wrote the researchers.

On the other hand, no changes in this primary hemostasis (the formation of the primary platelet “plug”) were observed in patients with cardiovascular disease taking fish oil supplements. “This indicates that the platelets of these patients are less responsive to fish oil treatment, or that the effects of fish oil supplements on primary hemostasis were masked by concomitant antithrombotic medication,”​ they added.

“Fish oil supplementation reduced primary hemostasis in most studies including healthy subjects, but fish oil supplementation did not increase bleeding in patients undergoing surgery or invasive procedures,” ​wrote the Danish scientists.

Source: Danish Medical Journal
2017, Volume 64, Number 5:A5366
“No impact of fish oil supplements on bleeding risk: a systematic review”
Authors: K. Munk Begtrup, et al.

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