Plasma phospholipid n-3 polyunsaturated fatty acids, fatal ischemic heart disease, and non-fatal myocardial infarction in older adults.
The Cardiovascular Health Study
BACKGROUND. Studies in middle-aged populations suggest that the intake of both long-chain and intermediate chain n-3 polyunsaturated fatty acids (PUFAs) is associated with a reduction in fatal ischemic heart disease (IHD) but not with non-fatal myocardial infarction (MI). OBJECTIVES. To assess the associations of plasma phospholipid n-3 PUFAs, a biomarker of n-3 PUFA intake, with both incident fatal IHD and incident non-fatal MI in older adults. METHODS. We conducted a nested case-control study using data from the Cardiovascular Health Study, a prospective cohort study of adults 65 and older. We identified 54 incident cases of fatal IHD (fatal MI and coronary heart disease death) and 130 incident cases of non-fatal MI. Controls, randomly selected, were matched to the cases on age, gender, clinic, and month of blood draw at a ratio of 1:1. Sampled cases and controls were free of IHD or stroke at the time of the blood draw. Bloods were collected at the baseline CHS examination. Plasma phospholipid PUFAs were measured using gas chromatography. RESULTS. An increase of one standard deviation in plasma phospholipid levels of combined docosahexaenoic acid (22:6n3) and eicosapentaneoic acid (20:5n3) (1% of total fatty acids) was associated with a decreased risk of fatal IHD (Odds ratio: 0.38, 95% CI [0.18-0.82]) but was not associated with non-fatal MI (Odds ratio: 1.01, 95% CI [0.78-1.30]) after adjustment for age, education, systolic blood pressure, weight, and fasting plasma glucose levels. Similarly, an increase of one standard deviation in plasma phospholipid levels of linolenic acid (0.06% of total fatty acids) was associated with a decreased risk of fatal IHD (Odds ratio: 0.46, 95% CI [0.22-0.95]) but was not associated with non-fatal MI (Odds ratio: 1.00, 95% CI [0.76-1.31]). CONCLUSIONS. Higher plasma phospholipid levels of long-chain and intermediate chain n-3 PUFAs are associated with a decreased risk of incident fatal IHD but are not associated with incident non-fatal MI in older adults. These findings are consistent with studies suggesting an anti-arrhythmic effect of n-3 fatty acids.