Long chain omega-3 fatty acids and cardiovascular disease: a systematic review

Introduction: Cardiovascular disease remains the commonest health problem in developed countries, and residual risk after implementing all current therapies is still high. The use of marine omega-3 fatty acids (DHA and EPA) has been recommended to reduce cardiovascular risk by multiple mechanisms. Objectives: To update the current evidence on the influence of omega-3 on the rate of cardiovascular events. Review Methods: We used the MEDLINE and EMBASE databases to identify clinical trials and randomized controlled trials of omega-3 fatty acids (with quantified quantities) either in capsules or in dietary intake, compared to placebo or usual diet, equal to or longer than 6 months, and written in English. The primary outcome was a cardiovascular event of any kind and secondary outcomes were all-cause mortality, cardiac death and coronary events. We used RevMan 5.1 (Mantel-Haenszel method). Heterogeneity was assessed by the I-2 and Chi(2) tests. We included 21 of the 452 pre-selected studies. Results: We found an overall decrease of risk of suffering a cardiovascular event of any kind of 10% (OR 0.90; [0.85-0.96], p = 0.001), a 9% decrease of risk of cardiac death (OR 0.91; [0.83-0.99]; p = 0.03), a decrease of coronary events (fatal and non-fatal) of 18% (OR 0.82; [0.75-0.90]; p < 1 x 10(-4)), and a trend to lower total mortality (5% reduction of risk; OR 0.95; [0.89-1.02]; p = 0.15. Most of the studies analyzed included persons with high cardiovascular risk. Conclusions: marine omega-3 fatty acids are effective in preventing cardiovascular events, cardiac death and coronary events, especially in persons with high cardiovascular risk.