Plasma Phospholipid Long-Chain Omega-3 Fatty Acids and Total and Cause-Specific Mortality in Older Adults: A Cohort Study

Background: Long-chain ?-3 polyunsaturated fatty acids (?3-PUFAs), including eicosapentaenoic acid (EPA) (20:5?-3), docosapentaenoic acid (DPA) (22:5?-3), and docosahexaenoic acid (DHA) (22:6?-3), have been shown to reduce cardiovascular risk, but effects on cause-specific and total mortality and potential dose-responses remain controversial. Most observational studies have assessed self-reported dietary intake and most randomised trials have tested effects of adding supplements to dietary intake and evaluated secondary prevention, thus limiting inference for dietary ?3-PUFAs or primary prevention.

Objective: To investigate associations of plasma phospholipid EPA, DPA, DHA, and total ?3-PUFA levels with total and cause-specific mortality among healthy older adults not receiving supplements.

Design: Prospective cohort study.

Setting: 4 U.S. communities.

Participants: 2692 U.S. adults aged 74 years (±5 years) without prevalent coronary heart disease (CHD), stroke, or heart failure at baseline.

Measurements: Phospholipid fatty acid levels and cardiovascular risk factors were measured in 1992. Relationships with total and cause-specific mortality and incident fatal or nonfatal CHD and stroke through 2008 were assessed.

Results: During 30,829 person-years, 1625 deaths (including 570 cardiovascular deaths), 359 fatal and 371 nonfatal CHD events, and 130 fatal and 276 nonfatal strokes occurred. After adjustment, higher plasma levels of ?3-PUFA biomarkers were associated with lower total mortality, with extreme-quintile hazard ratios of 0.83 for EPA (95% CI, 0.71 to 0.98; P for trend = 0.005), 0.77 for DPA (CI, 0.66 to 0.90; P for trend = 0.008), 0.80 for DHA (CI, 0.67 to 0.94; P for trend = 0.006), and 0.73 for total ?3-PUFAs (CI, 0.61 to 0.86; P for trend < 0.001). Lower risk was largely attributable to fewer cardiovascular than noncardiovascular deaths. Individuals in the highest quintile of phospholipid ?3-PUFA level lived an average of 2.22 more years (CI, 0.75 to 3.13 years) after age 65 years than did those in the lowest quintile.

Limitation: Temporal changes in fatty acid levels and misclassification of causes of death may have resulted in underestimated associations, and unmeasured or imperfectly measured covariates may have caused residual confounding.

Conclusion: Higher circulating individual and total ?3-PUFA levels are associated with lower total mortality, especially CHD death, in older adults.

 

Mozaffarian D Lemaitre RN King IB Song X Huang H Sacks FM Rimm EB Wang M and Siscovick DS (2013).
Ann Intern Med 158:515-525