For decades, there has been great interest in whether omega-3 fatty acids can lower rates of cardiovascular events. In 2018, results from the Reduction of Cardiovascular Events with Icosapent Ethyl-Intervention Trial (REDUCE-IT) were published in the New England Journal of Medicine and showed that a high dose of a purified ethyl ester of eicosapentaenoic acid (EPA) in patients at elevated cardiac risk significantly reduced cardiovascular events. Results from the trial led to US. Food and Drug Administration, Health Canada, and European Medicines Agency approval of the prescription drug icosapent ethyl for reducing cardiovascular risk in patients with elevated triglycerides, as well as updates to worldwide guidelines. But prior and subsequent studies of omega-3 fatty acid supplements that combine EPA and docosahexaenoic acid (DHA) have had mixed results.