Link Provided for Negative Cochrane Review on Omega-3s and Cardiovascular Outcomes
July 18: Here is the link to Cochrane review published yesterday. The balance of this news alert is a repeat of the information sent yesterday.
A highly anticipated, not to mention controversial, Cochrane systematic review of randomized clinical trials (RCTs) on omega-3s and cardiovascular outcomes was just published and, as expected, EPA and DHA were reported to have no heart health benefits. This review was produced as part of a partnership between Cochrane and the World Health Organization (WHO) to provide WHO evidence-based nutrition guidelines and is associated with the ongoing discussion by the Codex Committee on Nutrition and Foods for Special Dietary Uses (CCNFSDU) on establishing a nutrient reference value non-communicable disease (NRV-NCD) for EPA+DHA.
GOED has already reported on the draft report and provided extensive comments in documents submitted to the U.S. CCNFSDU delegation and the German Secretariatin advance of the last CCNFSDU meeting. A comparison of the current results revealed no relevant differences from the draft report, so these comments remain pertinent.
While GOED members can read additional details in the above links, the takeaway messages are:
- There are decades of research showing a cardioprotective effect of omega-3s. This includes meta-analyses, RCTs, epidemiological studies, animal studies and in vitro studies.
- While Dr. Lee Hooper, the project lead for this systematic review, says she is “… confident in the findings of this review which go against the popular belief that long-chain omega-3 supplements protect the heart,” her analysis focuses on only part of the existing evidence and even there contradicts previous meta-analyses that focused more carefully on some of the most relevant outcomes (cardiac death, blood pressure, triglycerides). What she gained in comprehensiveness, she lost in depth.
- Perhaps the biggest shortcoming of the CHD meta-analysis is that it is underpowered. Most readers of this article will assume that if there is a true effect on CHD mortality, for example, then this study would have a good chance of detecting it. In fact, that is not the case – a real effect of this size would be unlikely to be detected unless the number of participants were doubled. This stresses the importance of considering all existing science, not just RCTs.
- The way the authors define cardiovascular mortality is non-standard, and using this definition reduced the number of events considered, as compared to other published meta-analyses. This choice artificially reduced the chances of an already underpowered analysis to detect a significant effect.
In a particularly timely coincidence, a GOED-commissioned editorial review was just published by Dr. Kevin Maki exploring the reasons why omega-3s may not always show a clear benefit and describing the promising evidence supporting omega-3 supplementation for reducing the risk of cardiac death. Dr. Maki’s publication specifically looks at the results from his cardiac death meta-analysis compared to the results from the above mentioned draft report (now in final form as the present Cochrane review).
It is GOED’s understanding that a related review on RCTs on the entire polyunsaturated fatty acid category for the primary and secondary prevention of cardiovascular disease will be published in the near future and GOED anticipates the results to be reported as neutral.
GOED will monitor consumer media coverage of this report and respond accordingly.