Results of the study showed that elderly adults who have greater blood levels of omega-3 fatty acids - found almost uniquely in seafood and fatty fish - could decrease their total mortality risk by nearly 27% and their mortality risk from heart disease by 35%.
The study, led by a group of researchers from the Harvard School of Public Health (HSPH) and the University of Washington, revealed that older adults who had the greatest blood levels of the fatty acids found in fish - lived on average 2.2 years more than those with reduced levels.
Lead author Dariush Mozaffarian, associate professor in the Department of Epidemiology at HSPH, explained:
"Although eating fish has long been considered part of a healthy diet, few studies have assessed blood omega-3 levels and total deaths in older adults. Our findings support the importance of adequate blood omega-3 levels for cardiovascular health, and suggest that later in life these benefits could actually extend the years of remaining life."
The study was the first to examine how objectively measured blood biomarkers of fish intake are associated with total mortality and exact outcomes of mortality among the general population.
In earlier research, studies have found that eating fish, which contains ample protein and heart-healthy fatty acids, decreases the risk of dying from heart disease. However, the effect on other reasons for death, or on total mortality, is still a mystery.
In 2009, a study published in the European Heart Journal revealed that men who eat fatty fish only once a week can lower their risk of heart failure.
A separate study from September of last year suggested that fish intake can reduce the risk of heart attack, however, avoiding fish with the highest levels of mercury is important.
It has also been reported that regular fish consumption is linked to a lower risk of diabetes and cardiovascular risk.
How Does Fish Consumption Reduce Death Risk?Researchers from the current study aimed to get a more precise picture by analyzing biomarkers in the blood of adults not taking fish oil supplements, in an effort to provide the most accurate measurements of the possible outcomes of fish intake on several causes of death.
The authors analyzed 16 years of data from nearly 2,700 adults in the U.S. who were 65 years of age or older and who took part in the Cardiovascular Health Study (CHS) - a long-term study funded by the National Heart, Lung, and Blood Institute.
At baseline, all subjects were healthy. They had blood taken, underwent physical examinations and diagnostic testing, and were also asked about their lifestyle, health status, and medical history at baseline and follow-up.
The investigators examined the total proportion of blood omega-3 fatty acids, including three specific ones, in the volunteers' blood samples at baseline.
They adjusted for cardiovascular, demographic, dietary, and lifestyle factors and found that the three fatty acids - by themselves and together - were linked to a significant lower risk of mortality.
Docosahexaenoic acid, or DHA, was the specific fatty acid most significantly linked to lower risk of coronary heart disease (CHD) - by 40%.
Other noteworthy outcomes included:
- docosapentaenoic acid (DPA) - DPA was most significantly linked to lower risk of stroke death
- eicosapentaenoic acid (EPA) - was most significantly linked to decreased risk of nonfatal heart attack.
The investigators pointed out that the greatest jump in blood levels happened when going from very low consumption to about 400 mg per day, and after that, levels increased gradually.
Mozaffarian concluded, "The findings suggest that the biggest bang-for-your-buck is for going from no intake to modest intake, or about two servings of fatty fish per week."