Omega-3 Better Indicators of Mortality than Serum Cholesterol
Several recent studies have linked higher blood levels and/or dietary intakes of the long-chain n-3 polyunsaturated fatty acids (PUFAs) with greater longevity.
Plasma phospholipid n-3 PUFA levels were inversely associated with total mortality rates in the Cardiovascular Health Study, and similar associations were seen for this endpoint with the red blood cell (RBC) content of eicosapentaenoic acid (EPA) plus docosahexaenoic acid (DHA) in the Heart and Soul Study. This latter metric, called for simplicity the Omega-3 Index, has been proposed as a risk factor for death from cardiovascular disease (CVD).
In this direction, NIH researchers have now proved that omega-3 levels are better predictors of risk for death than serum cholesterol.
In the course of this study, the researchers compared the total serum cholesterol and Omega-3 fatty acids, two “risk factors” for heart disease, in 2,500 individuals aged 60 years, who were free of known cardiovascular disease (CVD) at baseline.
The researchers primarily focused on total mortality (death from any cause) as an endpoint, but also tracked death from CVD, cancer and other causes. In addition, they reported the associations between Omega-3 Index levels and a risk for any CVD event – fatal or not, heart attack or stroke. The population was 66 years of age at baseline and there were a few more females than males. The study followed these individuals for disease outcomes until about age 73. The results were statistically adjusted for a wide variety of factors that could influence the outcomes
The team determined that those who consumed the most omega-3 were 33 percent less likely to die during the study period than those who consumed the least, regardless of the cause of death. Furthermore, those who had a higher “Omega-3 Index,” or the combined amount of EPA and DHA in red blood cell membranes, were found to be at less risk for cardiovascular and coronary heart disease events and strokes.
“We all know that the serum cholesterol level is a major risk factor for CHD, and since the latter is a major cause of death in the Western world, it would be reasonable to expect that a high cholesterol level would portend higher risk for premature death,” said lead author Dr. William Harris. “This did not turn out to be the case here. When baseline serum cholesterol levels were substituted for the Omega-3 Index in the same multi-variable models, the former was not significantly associated with any of the tracked outcomes whereas the latter was related to 4 of the 5 outcomes assessed.”
Future studies are needed to try to replicate this finding and to determine if it is time to begin including the Omega-3 Index in routine blood screens along with cholesterol and glucose.
