The association between dietary omega-3 fatty acids and cardiovascular death: the Singapore Chinese Health Study

Background Although studies suggest that omega-3 fatty acids intake may reduce cardiovascular disease (CVD) mortality risk, few studies have differentiated dietary eicosapentaenoic/docosahexaenoic acid (EPA/DHA) from alpha-linolenic acid (ALA), and epidemiological research in Asian populations is limited. Methods The Singapore Chinese Health Study is a population-based cohort that recruited 63,257 Chinese adults aged 45-74 years from 1993 to 1998. Usual diet was measured at recruitment using a validated semiquantitative food-frequency questionnaire, and mortality information was identified via registry linkage up to 31 December 2011. Cox proportional hazard models were used to calculate hazard ratios (HRs) with adjustment for potential confounders. Results We documented 4780 cardiovascular deaths (including 2697 coronary heart disease (CHD) deaths and 1298 stroke deaths) during 890,473 person-years of follow up. Omega-3 fatty acids intake was monotonically associated with reduced risk of cardiovascular mortality. Compared to the lowest quartile, the HR was 0.88 (95% confidence interval, CI, 0.81-0.96), 0.88 (95% CI 0.80-0.97), and 0.83 (95% CI 0.74-0.92) for the second, third, and highest quartile, respectively (p-trend=0.003). Both EPA/DHA and ALA were independently associated with reduced risk of cardiovascular mortality: HR comparing extreme quartiles was 0.86 (95% CI 0.77-0.96, p-trend=0.002) and 0.81 (95% CI 0.73-0.90, p-trend<0.001), respectively. The associations were similar for deaths from CHD and stroke and persisted in participants who were free of CVD at baseline. Conclusions Higher intakes of marine (EPA/DHA) and plant (ALA) omega-3 fatty acids are both associated with reduced risk of cardiovascular mortality in a Chinese population.