Plasma α-Linolenic and Long-Chain ω-3 Fatty Acids Are Associated with a Lower Risk of Acute Myocardial Infarction in Singapore Chinese Adults123

Background: Long-chain marine omega-3 polyunsaturated fatty acids (n–3 PUFAs) are associated with a lower risk of acute myocardial infarction (AMI), but results for plant-derived α-linolenic acid (ALA; 18:3n–3) are inconsistent. Objective: We aimed to examine the association between plasma n–3 PUFAs and AMI risk and to explore potential mediation by cardiovascular disease risk factors. Methods: A nested case-control study with 744 incident AMI cases and 744 matched controls was conducted within the Singapore Chinese Health Study for participants aged 47–83 y. Conditional logistic regression was used to calculate the multivariable ORs for AMI with and without adjustment for cardiovascular disease risk factors, including blood lipids, blood pressure, C-reactive protein, serum creatinine, and glycated hemoglobin. Results: Plasma long-chain n–3 PUFAs were associated with lower AMI risk (multivariable OR: 0.62; 95% CI: 0.41, 0.94; for the highest compared with the lowest quartile; P-trend = 0.03). This association was not substantially changed after adjustment for cardiovascular disease risk factors. Dietary intakes of fish and long-chain n–3 PUFAs were similarly inversely associated with AMI risk. Plasma ALA was marginally associated with a lower risk of AMI (multivariable OR: 0.73; 95% CI: 0.51, 1.05; P-trend = 0.07) even in persons with high plasma concentrations of long-chain n–3 PUFAs. This association became significantly weaker after adjustment for blood pressure and LDL cholesterol. Conclusions: Plasma long-chain n–3 PUFAs are associated with a lower risk of AMI in this Asian population. Plasma ALA may be marginally associated with reduced AMI risk, even in persons with high concentrations of long-chain n–3 PUFAs, and this association may be partially mediated by lower blood pressure and LDL cholesterol.