A new meta-analysis out of Ioannina, Greece examined the effects of omega-3 fatty acids in 68,680 patients at high risk for cardiovascular events. There was a trend toward benefit in the prevention of sudden death, but the trials showed no effect on hard clinical outcomes, including all-cause mortality, cardiac death, sudden death, MI, or stroke [1]. “The meta-analysis, taking into account the recent and previously published trials, showed that omega-3 fatty acids did not significantly reduce the incidence of cardiovascular events,” senior investigator Dr Moses Elisaf (University Hospital of Ioannina, Greece) stated. “However, there was a trend toward benefit in terms of sudden death, about a 13% reduction, and myocardial infarction, about a 10% reduction. One of the reasons for the failure to achieve statistical significance according to Dr. Elisaf was that few of the trials included in the meta-analysis used the high-dose omega-3 fatty-acid supplements, that being 2 to 4 g per day as approved by the FDA, so more studies are needed to study the benefit of using the high-dose supplements to lower triglyceride levels and prevent cardiovascular events. In addition, many of the patients enrolled in the trials were already taking stronger lipid-lowering medications such as statins and nicotinic acid, so this would have lessened the effect of the fish oil on clinical outcomes. One of the pivotal trials that first suggested omega-3 fatty acids could reduce the risk of cardiovascular disease, GISSI, was conducted before patients were regularly treated with other cardiovascular medications, including cholesterol-lowering agents. “Today, our high-risk patients take aspirin and statins,” he said. “So, we have patients with much lower levels of LDL cholesterol, and the potential benefits of reducing mortality further with other agents, including omega-3 fatty acids, might be marginal.”
The meta-analysis included 20 clinical trials and studies published as early as 1989, but more than half of the clinical trials were published when statins were routinely recommended for the reducing the risk of cardiovascular disease. The average omega-3 dose used in the trial was 1.5 g/day, or 0.77 g/day eicosapentaenoic acid (EPA) and 0.60 g/day docosahexaenoic acid (DHA), which is higher than doses typically found in the over the counter supplements. Average treatment duration was two years, and the maximum was 6.2 years.
The study is published in the September 12, 2012 issue of the Journal of the American Medical Association.
The clinical guidelines published by the European Society of Cardiology (ESC), recommend omega-3 polyunsaturated fats, either through supplements or dietary changes, after MI. Similarly, the US Food and DrugAdministration (FDA) has approved high-dose omega-3 fatty acids ( an average of 2-4 grams per day) for the treatment of high triglyceride levels in patients with overt hypertriglyceridemia.
This study may raise some questions as to the benefit of adding fish oil to another lipid-lowering regimen or to using low-dose fish oil as a sole (no pun intended!) agent to control hyperlipidemia. It does not, however, negate the benefits that are seen in triglyceride lowering and the additional health benefits that are associated with use of fish oil including help in the treatment of inflammation, weight loss, arthritis, and improving insulin sensitivity. There have also been trials showing fish oil has a beneficial effect in treatment of various cancers. So before you give up on fish oil, think again: it has very few side effects and does have clinical benefits even beyond the scope of this study.