Can omega-3 fatty acids benefit patients with cardiovascular disease?

A new review says that supplementation with omega-3 fatty acids does not seem to reduce the risk of cardiovascular events and mortality for patients with a history of cardiovascular disease. Experts criticize that the review did not include many studies that showed a preventive effect.

To investigate the efficacy of eicosapentaenoic acid and docosahexaenoic acid supplementation in the secondary prevention of cardiovascular disease (CVD), the meta-analysis included 14 randomized controlled trials involving 20,485 patients with a history of CVD (1). The analysis showed that supplementation with omega-3 fatty acids did not reduce the risk of overall cardiovascular events, all-cause mortality, sudden cardiac death, myocardial infarction, congestive heart failure, or transient ischemic attack and stroke.

The researchers concluded that there is insufficient evidence of a secondary preventive effect of omega-3 fatty acid supplements against overall cardiovascular events among patients with a history of cardiovascular disease. Experts criticized that the meta-analysis included many studies that had failed to demonstrate a benefit because the trials were too small and trial terms too short, and furthermore used low doses. Of the 14 studies included, 10 studies involved patients who were on at least one anti-thrombotic or anti-hypertensive medication, potentially obscuring preventive effects of the omega-3 fatty acids. On the other hand, some of the best studies – ones that had demonstrated strongly positive results for secondary prevention of CVD (2-4) – were not included in the analysis. It has been estimated that low omega-3 fatty acid intakes account for 72,000–96,000 deaths per year from CVD in the United States alone (5).

1. Kwak S. M. et al. Efficacy of omega-3 fatty acid supplements (eicosapentaenoic acid and docosahexaenoic acid) in the secondary prevention of cardiovascular disease: A meta-analysis of randomized, double-blind, placebo- controlled trials. Arch Intern Med. Published online April 2012.
2. Burr M. L. et al. Effects of changes in fat, fish, and fibre intakes on death and myocardial reinfarction: diet and reinfarction trial (DART). Lancet. 1989; 2:757–761.
3. Tavazzi L. et al. Effect of n-3 polyunsaturated fatty acids in patients with chronic heart failure (the GISSI-HF trial): a randomised, double-blind, placebo- controlled trial. Lancet. 2008; 372:1223–1230.
4. Yokoyama M. et al. Effects of eicosapentaenoic acid on major coronary events in hypercholesterolaemic patients ( JELIS): a randomised openlabel, blinded endpoint analysis. Lancet. 2007; 369:1090–1098.
5. Danaei G. et al. The preventable causes of death in the United States: Comparative risk assessment of dietary, lifestyle, and metabolic risk factors. PLoS Med. 2009; 6:e1000058.