The participants had a history of cardiovascular disease in 14 studies.

In the intervention group, the participants took EPA alone (1,800 mg per day in 3 studies; 4,000 mg per day in 1 study) or with DHA (226–2,200 mg of EPA plus 150–840 mg of DHA per day).

In the control group, the participants generally took a statin (if the other group also took a statin) and/or a placebo (often corn oil or olive oil). The study duration ranged from 1 to 7.4 years.

Taking EPA alone reduced cardiovascular disease mortality risk by 21% versus the control. Supplementing with EPA and DHA combined reduced risk by 8%, but this result was not statistically significant.

EPA may be more effective alone than combined with DHA for cardiovascular disease mortality risk Original paper