Support for a cardiovascular benefit of omega-3 fatty acids, particularly eicosapentaenoic acid (EPA), has come from a new systematic review and meta-analysis of randomized trials.
The meta-analysis of 38 randomized controlled trials found that omega-3 fatty acids improved cardiovascular outcomes, with a greater reduction in cardiovascular risk in studies of EPA alone rather than of combined eicosapentaenoic plus docosahexaenoic acid (DHA) supplements.
The paper was published online in EClinicalMedicine.
Senior author Deepak Bhatt, MD, Brigham and Women’s Hospital, Boston, was also lead investigator of the REDUCE-IT trial, which is included in the analysis and showed a 25% relative risk reduction in major cardiovascular events with a high-dose EPA product.
But the REDUCE-IT trial has been mired in controversy, with suggestions that the benefit seen might have been exaggerated because of the use of a harmful placebo. In addition, a second large trial of high-dose omega-3 fatty acids, STRENGTH (which tested a combination EPA/DHA product) showed no benefit on cardiovascular outcomes.
Dr. Bhatt said the new meta-analysis provides “a totality of evidence” that “supports a robust and consistent benefit of EPA.”
In the review, the authors concluded: “In this systematic review and meta-analysis, we noted moderate certainty of evidence favoring omega-3 fatty acids for reducing cardiovascular mortality and outcomes. ... The magnitude of relative reductions was robust in EPA trials versus those of EPA+DHA, suggesting differential effects of EPA and DHA in cardiovascular risk reduction.”
But commenting on the publication for an interview, Steven Nissen, MD, Cleveland Clinic, who led the STRENGTH trial, pointed out that 85% of the EPA data in the new meta-analysis came from REDUCE-IT, so the results were a “foregone conclusion.”
“The purpose of a meta-analysis is to answer scientific questions when existing studies are too small to yield statistically robust results. That is not the case here,” Dr. Nissen stated.
He added: “There are only two major trials of EPA and both have important flaws. REDUCE-IT used a questionable placebo (mineral oil) and JELIS was an open-label trial that studied patients with baseline LDL [cholesterol] of 180 mg/dL that was not appropriately treated. A meta-analysis is only as good as the studies that it includes. The other EPA plus DHA studies were essentially neutral.”
Dr. Bhatt responded that, “to date, every randomized trial of EPA only has been positive. Some have been placebo controlled, some have been open label. This meta-analysis corroborates the results of each of those trials in a statistically robust way.”
He added: “Of course, REDUCE-IT is the most rigorous, contemporary trial of EPA. However, in our meta-analysis, even when excluding REDUCE-IT (or for that matter, JELIS), the EPA trials still significantly reduced cardiovascular events.”
Dr. Bhatt also pointed out that two randomized imaging studies, CHERRY and EVAPORATE, have shown benefits of EPA.
“Beyond the clinical trial data, there is a growing amount of evidence supporting the unique biological actions of different omega-3 fatty acids. EPA, in particular, appears to have the strongest basic science evidence supporting cardiovascular benefits. Overall, it is a remarkably consistent scientific story in support of EPA’s beneficial effects on cardiovascular health,” he stated.