In a recent meta-analysis, researchers found that while omega-3 supplements containing EPA and DHA reduced the risk of negative cardiovascular outcomes across 38 randomized clinical trials, the resulting health benefits were more pronounced in participants who consumed EPA-exclusive omega-3 supplements, rather than a combination of the omega-3 fatty acids EPA and DHA.
 
Relevant to these recent findings, one of the trials which was published in the New England Journal of Medicine (known as REDUCE-IT) showed that a high dose of a purified ethyl ester of EPA in patients at elevated cardiac risk significantly reduced cardiovascular events compared to a control group – this study led to the international approval of a prescription drug icosapent ethyl (Amarin) for reducing cardiovascular risk in patients with elevated triglycerides, as well as updates to world guidelines. The REDUCE-IT study was supported by Amarin.
 
Generally, prior research has shown that supplements which combine EPA and DHA have had mixed results in the realm of cardiovascular health benefits. The present meta-analysis, conducted by researchers from Brigham and Women’s Hospital and elsewhere, found that in the 38 trials they reviewed, omega-3 fatty acids improved cardiovascular outcomes overall, but were less effective when EPA and DHA were used in combination.
 
“REDUCE-IT has ushered in a new era in cardiovascular prevention,” Deepak L. Bhatt, MD, MPH, executive director of Interventional Cardiovascular Programs at the Brigham and lead investigator of the REDUCE-IT trial (who was also a lead author in this study) said. “REDUCE-IT was the largest and most rigorous contemporary trial of EPA, but there have been other ones as well. Now, we can see that the totality of evidence supports a robust and consistent benefit of EPA.”
 
In total, the trials the authors of the review covered more than 149,000 participants, and all of the studies covered key cardiovascular outcomes, including cardiovascular mortality, non-fatal mortality, and improved cardiovascular outcomes.
 
There are crucial biological differences between EPA and DHA, the authors of the review noted. While both are considered omega-3 fatty acids, they have different chemical properties that influence their stability and the strength of the effect that they can have on cholesterol molecules and cell membranes. No studies to date have studied the effects of DHA alone on cardiovascular outcomes, the authors noted.
 
“This meta-analysis provides reassurance about the role of omega-3 fatty acids, specifically prescription EPA,” Bhatt said. “It should encourage investigators to explore further the cardiovascular effects of EPA across different clinical settings.”