19 January 2017
Plasma Eicosapentaenoic Acid is Negatively Associated with All-cause Mortality among Men and Women in a Population-based Prospective Study
Miura, K. et al., Nutrition Research, 36: 1202-1209, 2016
QIMR Berghofer Medical Research Institute, Cancer and Population Studies Group, Brisbane, Queensland, Australia
While several reports have been published on the beneficial effects of increased intakes of long-chain omega-3 fatty acids from fish/fish oils and higher circulating levels of such on cardiovascular-related outcomes , the present study was directed towards assessing for a potential relationship between blood plasma levels of omega-3 fatty acids and the risk of death from all causes. For this purpose, blood samples were taken from 1008 qualifying subjects (mixed genders, ages ranging from 20-69 years with an average age of 50 years) followed by isolation of the plasma and determination of the fatty acid composition (including omega-3 fatty acids) of the isolated plasma phospholipid via thin-layer chromatography and subsequent gas-liquid chromatographic analyses.
During the follow-up interval of 17 years, 18 % of the subjects died (98 men and 81 women). After adjusting (multivariable model) for age, gender, smoking status, blood cholesterol, and serious medical conditions, higher levels of EPA in blood plasma phospholipid (biomarker for omega-3 status) were significantly associated with a lower risk of all-cause mortality in all subjects combined (lower by 19 %) and in both men and women (each lower by 22 %). For all subjects combined, no statistically- significant relationship of circulating levels of total omega-3 fatty acids, DHA, or omega-6 fatty acids to all-cause mortality was found. The authors concluded that, from this study on Australian adults, people with relatively high levels of plasma EPA have a reduced risk of all-cause mortality.
Dr. Holub’s Comments :
The present study did not evaluate the relationship of the omega-3 fatty acid status to various causes of mortality (cardiovascular, cancer, other). Although higher levels of EPA , DHA , and EPA/DHA combined (intakes or blood levels) have all been associated with reduced ‘hard’ cardiovascular events (fatal and non-fatal) in many previous population studies, the apparent protective effect of EPA but not DHA in this particular study on all-cause mortality is of interest. While EPA and DHA have many common beneficial effects on assorted risk factors for cardiovascular disease, they do exhibit some divergent effects on serum lipoproteins and inflammatory effects (Curr. Atheroscler. Rep., 13: 474-483 (2011); Am. J. Ther., 23: in press (2016)). For example, EPA has a somewhat more potent effect on reducing vascular inflammation whereas DHA appears to offer some advantages on other parameters. Thus , maintaining a regular intake of both long-chain omega-3 fatty acids would appear to be prudent advice for complementary protection against and management of chronic disorders including the reduction in risk of all-cause mortality.