Abstract P036: RBC Omega-3 Fatty Acids, Incident CVD and Total Mortality: Framingham Heart Study

Abstract

Background: The potential role of the marine omega-3 fatty acids (FA) EPA and DHA in cardiovascular disease (CVD) is unclear. Diet- and biomarker-based prospective studies have shown cardioprotective associations while several recent (relatively low dose, short term) randomized trials have shown no benefit. Methods: We examined CV outcomes and death in 2899 individuals in the Framingham Heart Study Offspring cohort (mean age 66 years, 54% women; 399 individuals had prior CVD) as a function of baseline levels of EPA+DHA in erythrocyte membranes (the Omega-3 Index). The latter is expressed as a % of total membrane FAs and is a validated surrogate for tissue EPA+DHA content. Clinical outcomes were monitored for up to 9.5 years (median follow up, 7.26 years). Cox proportional hazards models stratified by prior CVD were adjusted for a variety of demographic characteristics, clinical status and RBC omega-6 FA content. Results: There were 296 CV events, 157 CHD events, 116 ischemic strokes, 76 CVD deaths, and 362 deaths from all causes. A 1-SD higher Omega-3 Index was associated with significantly lower risks for total CVD (29%), ischemic stroke (39%), and total mortality (24%) (Table). In individuals in the bottom 20% of Omega-3 Index (vs. the top 20%, i.e., <4.2% vs >6.8%) risk was reduced by 44% for any CV event, by 65% for ischemic stroke, by 65% for CHD death, and by 53% for death from any cause (Table). Relations with these outcomes for EPA and DHA separately were weaker than for the combined metric but in the same direction. Conclusions: Higher circulating levels of the marine omega-3 fatty acid levels are associated with reduced risk for incident CVD and ischemic stroke and for death from CHD and all-causes. Evidence for a causal connection between omega-3 fatty acids and these outcomes must await the results of longer-term and/or higher-dose intervention studies that are currently in progress.