Polyunsaturated fatty acids intake, omega-6/omega-3 ratio and mortality: Findings from two independent nationwide cohorts

Background & aims Polyunsaturated fatty acids (PUFA) have been reported to exert pleiotropic protective effects against various chronic diseases. However, epidemiologic evidence linking specific PUFA intake to mortality has been limited and contradictory. We aim to assess the associations between specific dietary PUFA and mortality among adults in China and America, respectively. Methods Participants from China Health and Nutrition Survey (CHNS, n = 14,117) and National Health and Nutrition Examination Survey [NHANES (n = 36,032)] were prospectively followed up through the year 2011. Cox regression models were used to investigate hypothesized associations. Results A total of 1007 and 4826 deaths accrued over a median of 14 and 9.1 years of follow-up in CHNS and NHANES, respectively. Dietary marine omega-3 PUFA was robustly associated with a reduced all-cause mortality [Hazard ratio (HR) comparing extreme categories: 0.74, 95% CI: 0.61–0.89; P < 0.001 for trend] in CHNS. Nevertheless, this inverse relationship was not observed in NHANES. The overall mortality was positively associated with the intake of α-linolenic acid (ALA) (HR comparing extreme quartiles: 1.23, 95% CI: 1.01–1.50; P = 0.054 for trend) in CHNS, whereas weak inverse associations of ALA (P = 0.035 for trend) and LA (P = 0.027 for trend) with all-cause mortality were found in NHANES. Increased dietary intake of arachidonic acid was consistently linked with reduced all-cause mortality both in NHANES and CHNS. Importantly, consuming PUFA at an omega-6/omega-3 ratio of 6–10 was associated with a lower risk of death in CHNS. Conclusions Intakes of different specific PUFA show distinct associations with mortality and these relationships also vary between Chinese and US populations. These findings suggest maintaining an omega-6/omega-3 balance diet for overall health promotion outcomes (NCT03155659).