Fish oil supplements ARE SAFE and do not increase the risk of bleeding!

According to a recent study, fish oil supplements do not increase the risk of bleeding during or after surgery. Although, in fact, omega-3-rich supplements reduce the ability of platelet aggregation in healthy subjects, this biochemical effect is not reflected in increased bleeding, thus contradicting some previous research and disproving the need to discontinue supplement consumption prior to operations or other invasive interventions.

These are the main findings of a review of the scientific literature conducted by researchers at Aarhus University Hospital, Denmark. The research, which analyzed data from numerous publications regarding the link between fish oil supplements and bleeding, was published in the Danish Medical Journal.

Omega-3 and bleeding risk, a controversial relationship

Interest in fish oil and omega-3s has increased over the past few decades, that is, since Dr. Jorn Dyerberg and his colleagues reported their cardiovascular benefits in the early 1970s by studying the Inuit of Greenland. Dr. Dyerberg had also found that this population showed significantly longer bleeding times than the Danish population. 

This phenomenon has been extensively studied over the years and never fully elucidated, and the debate is still open as to whether or not fish oil supplementation should be discontinued before surgery or other invasive procedures. The mechanism by which omega-3 fits into the process of blood clotting is based on the fact that, after ingestion, EPA goes on to replace Arachidonic Acid in the membranes of platelets, the small blood components essential for clotting and blocking excessive bleeding. This EPA replacement reduces the level of a plasma molecule, Thromboxane B2, which is a metabolite of Thromboxane A2. The latter stimulates platelet aggregation, that is, the ability to adhere to one another; consequently, omega-3 consumption could inhibit this mechanism by promoting blood loss. Bleeding in surgery is part of the postoperative complications, and although it is infrequent it turns out to be a cause of high mortality. 

In fact, complications of excessive bleeding are responsible for at least 1/10 of operative deaths. Bleeding can begin before, during, and after surgery and depends on the interaction between surgical technique and the patient's ability to hemostasis. Hemostasis consists of a series of biochemical and cellular events that concur to block the escape of blood from an injured blood vessel.

Fish oil supplements do not increase the risk of bleeding

The new systematic review, published in the Danish Medical Journal, which looked at data from 16 studies of patients undergoing surgery, found that fish oil supplements did not increase the risk of bleeding or bleeding loss. In fact, no study analyzed had reported increased bleeding in patients exposed to fish oil supplementation preoperatively and/or postoperatively, compared with controls. 

Paradoxically, two studies had instead shown a reduction in the need for blood transfusions among patients who received the supplements, and, in addition, fish oil exposure was associated with less bleeding in a meta-analysis study of cardiac surgery. These data contrast with those of some scientific research that has found an association between marine-derived omega-3 supplements and reduced platelet aggregation, which would suggest an increase in the time it takes for blood clots to form and stop bleeding. 

According to the same Danish researchers who conducted the study, the biochemical effect of omega-3 supplements, in healthy people, is not reflected in increased bleeding during surgery, and therefore the research does not support the need to discontinue fish oil supplements prior to surgery or other invasive procedures. Commenting on this, Harry Rice, vice president of the Organization for EPA and DHA (Goed), expressed gratitude to the study authors. "Not surprisingly, the results confirm those of some papers that had reported that fish oil does not increase the risk of bleeding. It is particularly noteworthy that the authors also reviewed two studies showing the need to reduce blood transfusions in operated patients taking fish oil," Rice said.

More significant details of the study

Publications that included a minimum of 20 healthy subjects and those on patients undergoing surgery who had followed omega-3 supplementation from fish oil were included in the review. Of the research reviewed, those that had involved healthy people showed that, in general, EPA and DHA supplements are associated with a reduction in platelet aggregation. Data from two studies showed that this platelet aggregation normalized in two and three months after supplementation ended. 

"This suggests that primary hemostasis is affected by exposure to fish oil for more than 10 days, which is the average duration of platelets, after withdrawal," the researchers wrote. Primary hemostasis is the first event in hemostasis, the one in which the narrowing of the blood vessel promotes the clumping of platelets and the formation of the platelet plug that begins to block blood loss. 

"On the other hand, no change at this stage was 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 effect of supplements during primary hemostasis was masked by antithrombotic drugs," the researchers added. Although the later stages of hemostasis have been little investigated, overall, fish oil supplementation had no effect on secondary hemostasis or fibrinolysis.

Results do not support discontinuation of supplementation before surgery

According to the researchers, the review study did not show an increased risk of hemorrhage postoperatively or during surgery in patients consuming fish oil supplements. However, these fatty acids significantly reduced primary hemostasis in healthy subjects, but the biochemical effect of the supplements did not increase the bleeding risk during surgery. According to these observations, therefore, there is no need to stop treatment with fish oil supplements before surgery. To stay up to date with the latest news from Omega 3 scientific research, write to our newsletter. 

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