August 12/The Lancet -- Much evidence shows that the marine omega-3 fatty acids eicosapentaenoic acid and docosahexaenoic acid have beneficial effects in various cardiac disorders, and their use is recommended in guidelines for management of patients after myocardial infarction. However, questions have been raised about their usefulness alongside optimum medical therapies with agents proven to reduce risk of cardiac events in high-risk patients. Additionally, there is some evidence for a possible pro-arrhythmic effect in subsets of cardiac patients. Some uncertainly exists about the optimum dose needed to obtain beneficial effects and the relative merit of dietary intake of omega-3 polyunsaturated fatty acids versus supplements. The following reviews evidence for the effects of omega-3 polyunsaturated fatty acids on various cardiac disorders and the risk factors for cardiac disease, while also assessing areas of uncertainty needing further research.
Introduction The marine omega-3 polyunsaturated fatty acids (n-3 PUFAs) eicosapentaenoic acid and docosahexaenoic acid are present mainly in oily fish and commercially available supplements, which are available either over the counter (as fish oils) or as concentrated pharmaceutical preparations. Such supplements are becoming increasingly popular, with several health benefits attributed to them. Substantial benefits are reported in relation to diseases of the cardiovascular system, and guidelines recommend use of these agents in some cardiac disorders.1,2 Although much research has been focused on this area during the past three decades, an absence of clarity remains about some basic issues, such as the appropriate dose needed to achieve beneficial reduction in cardiovascular events. Additionally, some doubt exists about some established benefits and assumed mechanisms of action, whereas new areas of use and mechanisms are being identified. We review evidence for the effects of n-3 PUFAs on various cardiac disorders and the risk factors for cardiac disease. We also assess areas of uncertainty needing further research.