Abstract
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.