09 January 2017
A Meta-Analysis of Randomized Controlled Trials and Prospective Cohort Studies of Eicosapentaenoic and Docosahexaenoic Acid Long-Chain Omega-3 Fatty Acids and Coronary Heart Disease Risk
Alexander, D. D. et al., Mayo Clinic Proceedings, 92: 15-29, 2017
Dept. of Epidemiology, EpidStat Institute, Ann Arbor, Michigan, USA
Previous reviews and meta-analyses have indicated somewhat mixed results with respect to the potential benefits of EPA/DHA omega-3 fatty acid intakes when selected randomized controlled trials (RCTs) or prospective cohort studies were chosen for the evaluation of diverse vascular and less-defined coronary outcomes. According to the authors, the present systematic literature search is the most comprehensive quantitative assessment to date of the relationship between EPA/DHA intakes from foods and supplementation on the specific risk of coronary heart disease (CHD). After reviewing 18 RCTs (93,000 subjects) and 16 prospective cohort studies (732,000 subjects), the findings indicate a non-statistically 6 % reduction in CHD risk among all populations in RCTs and a statistically-significant 18 % reduction based on prospective cohort studies. Interestingly, the reduced risk of adverse CHD risk (by 14 to 16 %) associated with omega-3 fatty acid intakes was particularly apparent amongst those with traditional risk factors (elevated triglyceride and/or LDL (low-density lipoprotein) cholesterol levels)). The authors concluded that intakes of EPA plus DHA may be associated with reducing CHD risk with a greater benefit observed among higher-risk populations in RCTs.
Dr. Holub’s Comments :
Future studies will be of interest to better specify the ‘ideal’ quantitative intakes of EPA/DHA (including varying ratios of EPA:DHA) in sub-groups of subjects with diverse risks for CHD. With respect to elevated circulating triglyceride levels alone as a risk factor, data from the National Health and Nutrition Examination Survey (USA) has reported that 20-29 % of the population (ages 20 and over) falls into the risk category. It is noted that, subsequent to the published literature coverage date as assessed by the present authors, recent studies have reported upon higher blood levels of EPA/DHA being associated with lower cardiovascular mortality, higher EPA/DHA intakes offering protection from cardiac mortality, and reduced mortality and heart attacks after initial myocardial infarction with EPA/DHA supplementation (as egs., see Kleber et al., Ather.,252: 175-181 (2016); Sala-Vila et al., J. Am. Heart Assoc., in press (2016); Greene et al., Am. J. Cardiol., 117: 340-346 (2016)).