April 9th, 2012
Meta-Analysis: No Secondary CV Prevention Benefits for Omega-3 Fatty Acid Supplements
A new meta-analysis published in the Archives of Internal Medicine finds no evidence to support claims of a beneficial effect of omega-3 fatty acid supplements on secondary CV prevention.
Sang Mi Kwak and colleagues in the Korean Meta-analysis Study Group analyzed data from more than 20,000 patients with a history of CV disease who were randomized in 14 double-blind, placebo-controlled trials. There were no significant differences for most of the endpoints measured in the studies:
- Cardiovascular events: RR 0.99, CI 0.89-1.09
- Mortality: RR 0.96, CI 0.90-1.02
- Sudden cardiac death: 0.93, CI 0.66-1.30
One endpoint, cardiovascular death, achieved nominal significance but was no longer significant after excluding a study with methodological problems:
- Cardiovascular death (overall): RR 0.91, CI 0.84-0.99
- Cardiovascular death (excluding 1 trial): RR 0.92, CI 0.35-1.01
In an accompanying editorial, Frank Hu and JoAnn Manson note that most of the included trials “were very small short-term studies and were not designed to evaluate CVD end points.” They also point out that the meta-analysis did not include two large open-label trials (GISSI-Prevenzione and JELIS) that did offer evidence in favor of omega-3 supplements. But, they write, “there is no conclusive evidence to recommend fish oil supplementation for primary or secondary prevention of CVD.”
However, a diet high in fatty fish (>=2 servings of marine fish per week) should continue to be recommended for the general population and for patients with existing CVD because fish not only provides omega-3 fatty acids but also may replace less healthy protein sources, such as red meat. Individuals who are unable or unwilling to eat fish or related products should consider increasing their consumption of plant-derived omega-3 fatty acid (α-linolenic acid). For primary or secondary prevention, omega-3 supplementation cannot supersede an overall healthy diet, but a cardioprotective diet needs to be rich in omega-3 fatty acids.