Fish oil is rich in omega-3 fatty acids EPA and DHA. Increased intake of EPA and DHA is beneficial for cardiovascular health, cognitive function, mental health, maternal and child health, immunity and inflammation. EPA and DHA supplements are becoming more and more popular across a wide diversity of people, from healthy individuals to vulnerable population with impaired health.
Higher omega-3 concentrations may compete with fatty acids such as arachidonic acid for metabolizing enzymes. The interaction results in a decreased production of compounds that induce platelet aggregation and an increased production of compounds with anti-platelet properties, hence the anticoagulation benefits of omega-3. However, for patients who are under antithrombotic therapy (either with platelet aggregation inhibitors such as aspirin or anticoagulant drugs such as warfarin), the potential risk of bleeding due to the concurrent use of omega-3 fatty acids has been a concern by many clinicians, particularly surgeons.
Multiple clinical studies have been conducted to investigate whether omega-3 fatty acids pose a clinically significant bleeding risk. So far, the findings have been consistent:
A 2004 Cochrane review of 48 randomized controlled trials and 41 epidemiological analyses concludes that 0.4-7 g/day omega-3 fatty acids do not result in any change in clinical bleeding manifestations.
A 2007 review of 19 clinical studies involving nearly 4400 surgical patients concludes that the risk for clinically significant bleeding was virtually nonexistent with the use of 1.4-21 g/day of omega-3 fatty acid supplements, even with the concurrent use of antiplatelet or antithrombotic medications.
A 2013 systematic review of 10 randomized trails involving nearly 1000 adults 60 years or older concludes that there is no difference in total adverse event rates between daily use of placebo or 0.03-1.86 g EPA and/or DHA for 6-52 weeks.
A 2014 review of 7 randomized controlled trails and 3 epidemiological studies concludes that omega-3 fatty acid treatment has no effect on the risk of clinically significant bleeding and there is no support for discontinuing the use of omega-3 fatty acids before invasive procedures.
A 2017 systematic review based on 32 publications on healthy subjects and 20 publications on patients undergoing surgery finds that fish oil supplements reduce platelet aggregation in healthy subjects and do not increase intra- or post-operative bleedings in patients, and concludes that discontinuation of fish oil supplements prior to surgery is not recommended.
