Omega-3 Supplements' Impact on Cardiovascular Outcomes

A meta-analysis including 20 studies and more than 68,000 patients finds that the popular supplements do not improve major cardiovascular outcomes.

Omega-3 fatty acid supplementation has no significant effect on major cardiovascular outcomes, according to the results of a meta-analysis of randomized clinical trials published in the September 12, 2012, edition of the Journal of the American Medical Association. The meta-analysis included 20 studies published between 1989 and 2012 with a total of 68,680 patients.

The researchers selected trials that evaluated the effect of omega-3 intake on all-cause mortality, cardiac death, sudden death, heart attack, or stroke. The median treatment duration of the trials was 2 years, and the minimum duration was 1 year. Two of the trials included increased omega-3 intake through dietary counseling, while the other 18 included omega-3 supplements. In the trials including supplements, the average dose was 1.51 grams of omega-3 fatty acids per day.

When all studies were included, no statistically significant change in relative or absolute risk was found for all-cause mortality, cardiac death, sudden death, heart attack, or stroke.

Positive effects of omega-3 consumption on major cardiovascular outcomes have been found in some previous studies, but not in others. Proposed mechanisms of action for omega-3s have included reducing triglyceride levels, preventing serious arrhythmias, and decreasing platelet aggregation and lowering blood pressure. Use of omega-3 supplements to improve heart health has been supported by major societies’ guidelines, but the FDA has only approved their use to lower triglycerides in patients with hypertriglyceridemia.

The authors of the current study note that it differs from previous meta-analyses and systematic reviews of the topic by including “all the available published randomized evidence addressing the cardiovascular benefit of the omega-3 supplementation regardless of methodological study characteristics, the prevention setting, or the supplementation mode, opting for the totality of the evidence and thus a valid interpretation of the results.”

The authors conclude that these results “do not justify the use of omega-3 as a structured intervention in everyday clinical practice or guidelines supporting dietary omega-3 PUFA [polyunsaturated fatty acid] administration.”