Fish oil and omega-3 fatty acids in cardiovascular disease: do they really work?

Abstract

Omega-3 fatty acids, which are found abundantly in fish oil, exert pleiotropic cardiometabolic effects with a diverse range of actions. The results of previous studies raised a lot of interest in the role of fish oil and omega-3 fatty acids in primary and secondary prevention of cardiovascular diseases. The present review will focus on the current clinical uses of omega-3 fatty acids and provide an update on their effects. Since recently published trials in patients with coronary artery diseases or post-myocardial infarction did not show an effect of omega-3 fatty acids on major cardiovascular endpoints, this review will examine the limitations of those data and suggest recommendations for the use of omega-3 fatty acids.

Figure 1

Beneficial effects of omega-3 fatty acids. TG, triglycerides; RLP, remnant lipoproteins; RBC, red blood cells.

Figure 2

Long-term eicosapentaenoic acid treatment inhibits myocardial Rho-kinase activation induced by ischaemia/reperfusion. Male pigs were treated with either a control chow or eicosapentaenoic acid (600 mg/kg/day) for 3 weeks and were subjected to myocardial ischaemia by 90 min occlusion of the left circumflex coronary artery and subsequent 60 min reperfusion. The eicosapentaenoic acid group had increased eicosapentaenoic acid level in red blood cells (eicosapentaenoic acid 4.30 ± 0.63 mol%). The eicosapentaenoic acid treatment significantly ameliorated myocardial ischaemia/reperfusion injury and significantly inhibited myocardial Rho-kinase activity, assessed by the extent of myosin-binding subunit (MBS) phosphorylation. Top panel (A) shows representative western blots of myocardial expression of phosphorylated (p)- and total (t)-MBS. Bottom panel (B) shows quantitative results of the ratio of p-MBS to t-MBS, indicating Rho-kinase activity. Results are expressed as mean ± SD. (Reproduced from Gao et al. with permission.)

Figure 3

The association between seafood consumption and fatal coronary heart disease. (Reproduced from Kromhout with permission.)

Figure 4

Effect of eicosapentaenoic acid–docosahexaenoic acid on cardiovascular diseases in the Alpha Omega Trial (AOT) and the GISSI-Prevenzione trial (GISSI-P). CVD, cardiovascular diseases; CAD, coronary artery diseases.