Coronary heart disease and omega-3 consumption
The guidelines of the American College of Cardiology, the American Heart Association and other important health organizations all recommend diets the include the long-chain omega-3 polyunsaturated fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) as beneficial to cardiac health. However, results from published studies do not always support the beneficial effects of omega-3 fatty acids fatty acids on coronary heart disease (CHD). With the aim of clarifying the effects, a meta-analysis was performed which included only randomised, controlled trials specifically on the risk of CHD (including myocardial infarction, sudden cardiac death, coronary death and angina) published in Ovid/Midline, PubMed, Embase and Cochrane Library from 1 January 1947 to 2 November 2015.
The reduction effect on triglyceride (TG) levels in subjects with hypertriglyceridemia after omega-3 supplementation is well documented and the results of this meta-analysis indicate that EPA+DHA administration reduces triglyceride levels in subjects with TG ≥ 150 mg/dl (thus reducing the risk of CHD), but not when when levels are within normal limits. Similarly, the risk of CHD decreases after administering EPA+DHA in patients with low-density lipoprotein cholesterol (LDL-C) ≥ 130 mg/dl, but not in those with LDL-C < 130 mg/dl. Although a few previous meta-analyses showed that administration of omega-3 fatty acids can increase LDL-C (particularly in patients with very high triglyceride levels), the beneficial effect on the risk of CHD observed in this analysis in subjects with high LDL-C levels could reflect the conversion of LDL-C into larger and less atherogenic particles (a process described after administering omega-3 fatty acids in a number of randomised, controlled trials). These findings are relatively consistent with meta-analyses conducted in the last decade, in which a reduction of 10 to 30% in the risk of cardiac/coronary death has been observed in relation to high long-chain omega-3 polyunsaturated fatty acid consumption.
These results from randomised, controlled trials are accompanied by findings in prospective cohort studies: significant inverse relationships (both potent and consistent) between fish consumption and death from heart disease. This is worth highlighting, despite the different methods used in the types of study.
In short, this meta-analysis of the results from randomised, controlled studies shows a significant reduction in the risk of CHD through EPA+DHA consumption, with greater benefits to high-risk subjects, including those with high TG and LDL-C levels. The analysis of prospective studies showed (significant) inverse relationships between EPA-DHA consumption and the risk of any CHD event.
Given the relevance of heart disease-related morbidity and mortality, the fact that an inadequate diet is the main cause of CHD (a diet low in sea-origin omega-3 fatty acids is a contributing factor to disability-adjusted life years due to ischaemic heart disease and has a potential effect on mortality), EPA+DHA consumption should be recommended due to their beneficial effects on heart and overall health.
Alexander DD, Miller PE, Van Elswyk ME et al. A Meta-Analysis of Randomized Controlled Trials and Prospective Cohort Studies of Eicosapentaenoic and Docosahexaenoic Long-Chain Omega-3 Fatty Acids and Coronary Heart Disease Risk. Mayo Clinic Proceedings. 2017;92(1):15-29.