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

According to a recent study, fish oil supplements do not increase the risk of bleeding during or after surgery. Although omega-3 rich supplements reduce platelet aggregation capacity in healthy subjects, this biochemical effect does not translate into increased bleeding, contradicting some previous research and disproving the need to stop taking supplements before surgeries or other invasive procedures.

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

Omega-3 and bleeding risk, a controversial relationship

Interest in fish oil and omega-3 has increased over recent decades since Dr. Jorn Dyerberg and colleagues first reported their cardiovascular benefits in the early '70s, studying the Inuit of Greenland. Dr. Dyerberg also found that this population exhibited significantly longer bleeding times than the Danish population. 

This phenomenon has been widely studied over the years and never fully clarified, and the debate about whether to discontinue fish oil supplementation before surgery or invasive procedures is still open. The mechanism by which omega-3s interact with blood coagulation is based on the fact that, after ingestion, EPA replaces Arachidonic Acid in platelet membranes — the small blood components essential for coagulation and stopping excessive bleeding. This EPA substitution reduces the level of a plasma molecule, Thromboxane B2, which is a metabolite of Thromboxane A2. The latter stimulates platelet aggregation, i.e., the ability to stick together; consequently, omega-3 consumption could inhibit this mechanism, favoring blood loss. Bleeding in surgery is part of postoperative complications and, although rare, it is a cause of high mortality. 

Complications from excessive bleeding are responsible for at least 1/10 of surgical deaths. Bleeding can start before, during, and after surgery and depends on the interaction between the surgical technique and the patient’s hemostatic capacity. Hemostasis consists of a series of biochemical and cellular events that work to stop blood flow from an injured blood vessel.

Fish oil supplements do not increase bleeding risk

The new systematic review, published in the Danish Medical Journal, which examined data from 16 studies conducted on surgical patients, found that fish oil supplements do not increase the risk of bleeding or blood loss. None of the studies analyzed reported increased bleeding in patients exposed to fish oil supplementation pre- and/or post-surgery compared to controls. 

Paradoxically, two studies showed a reduced need for blood transfusions among patients who received supplements, and exposure to fish oil was associated with less bleeding in a meta-analysis study on cardiac surgery. These data contrast with some scientific research that found an association between marine omega-3 supplements and reduced platelet aggregation, which would suggest a longer time needed to form blood clots and stop bleeding. 

According to the Danish researchers who conducted the study, the biochemical effect of omega-3 supplements in healthy individuals does not result in increased bleeding during surgery, and thus the research does not support the need to discontinue fish oil supplements before surgery or other invasive procedures. Commenting on this, Harry Rice, Vice President of the EPA and DHA Organization (GOED), expressed appreciation for the study authors. “It is not surprising that the results confirm those of some works that reported fish oil does not increase bleeding risk. It is particularly noteworthy that the authors also examined two studies showing reduced blood transfusion needs in operated patients taking fish oil,” said Rice.

Key study details

The review included publications with a minimum of 20 healthy subjects and those on surgical patients who had followed omega-3 supplementation from fish oil. Among the analyzed research, those involving healthy individuals showed that, in general, EPA and DHA supplements are associated with reduced platelet aggregation. Data from two studies indicated that this platelet aggregation normalizes two to three months after supplementation ends. 

“This suggests that primary hemostasis is influenced by exposure to fish oil for more than ten days, i.e., the average lifespan of platelets, after discontinuation,” wrote the researchers. Primary hemostasis is the first hemostatic event, during which blood vessel constriction promotes platelet clumping and the formation of the platelet plug that begins to block blood loss. 

“On the other hand, no change in this phase was observed in cardiovascular patients taking fish oil supplements. This indicates that the platelets of these patients are less reactive 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 were little investigated, overall, fish oil supplementation had no effect on secondary hemostasis or fibrinolysis.

The results do not support discontinuing supplementation before surgery

According to the researchers, the review study showed no increase in postoperative or intraoperative bleeding risk 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 bleeding risk during surgery. Therefore, based on these observations, it is not necessary to stop fish oil supplementation before surgery. To stay updated on the latest scientific research news about Omega 3, subscribe to our newsletter. 

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