Effects of Omega-3 Fatty Acids on Cardiovascular Disease.
Effects of Omega-3 Fatty Acids on Cardiovascular Disease.
Year: 2004
Authors: Tufts-New England Medical Cent
Publication Name: AHRQ Publication.
Publication Details: Number 94.
Abstract:
Under its Evidence-based Practice Program, the Agency for Healthcare Research and Quality (AHRQ) has developed scientific information for other agencies and organizations on which to base clinical guidelines, performance measures, and other quality improvement tools. Numerous studies have examined the relationship between dietary fat and cardiovascular disease (CVD). Most early epidemiology studies noted very low cardiovascular mortality in populations with high fish consumption. The primary omega-3 fatty acids of interest in this report include eicosapentaenoic acid (EPA, 20:5 n-3) and docosahexaenoic acid (DHA, 22:6 n-3), which are derived primarily from marine sources, and alpha-linolenic acid (ALA, 18:3 n-3), which is derived primarily from plant sources. This report examines evidence addressing both the association in humans between omega-3 fatty acids and cardiovascular intermediate outcomes and risk factors and the association between omega-3 fatty acids and tissue or plasma levels of omega-3 fatty acids and was prepared by the Tufts-New England Medical Center (Tufts-NEMC) Evidence-based Practice Center (EPC). Overall, there is strong evidence that fish oils have a strong beneficial effect on triacylglycerides (TG) that is dose-dependent and similar in various populations. There is also evidence of a very small beneficial effect of fish oils on blood pressure and possible beneficial effects on coronary artery restenosis after angioplasty, exercise capacity in patients with coronary atherosclerosis, and possibly heart rate variability, particularly in patients with recent myocardial infarctions. No consistent beneficial effect is reported for other analyzed CVD risk factors or intermediate markers. However, there is also no consistent evidence of a detrimental effect of omega-3 fatty acids on glucose tolerance. There are little available data, however, on how the effect of omega-3 fatty acids on CVD risk factors and intermediate markers may differ depending on people’s underlying conditions and risk of CVD, amount of omega-3 fatty acid consumed, duration of consumption, or source or type of omega-3 fatty acids. Given the limitations of the current evidence, the authors make several recommendations for future research: 1) Future studies on CVD risk factors and intermediate outcomes should address the questions of possible different effects of omega-3 fatty acids in different sub-populations and different effects related to different covariates, including dose and duration of intake; 2) More multi-center trials are needed to assess the effect of ALA, independent of EPA+DHA, on CVD risk factors and intermediate outcomes; 3) Additional research is needed to clarify the effect of omega-3 fatty acids on markers of glucose tolerance; 4) The omega-6/omega-3 ratio of subjects’ total diet (including supplements) should be estimated, reported, and analyzed for its effect on outcomes; 5) Attempts should be made to determine the effect of higher fish intake on the consumption of other foods in the diet, specifically meat and cheese (sources of saturated fat) and 6) Future prospective cohort studies and diet trials on fish consumption should pay special attention to collecting data with regard to fish consumed, including the type of fish and method of preparation.
