The research, published in JAMAs Annals of Internal Medicine, is the first to investigate how objectively measured blood biomarkers of omega-3 consumption relate to total mortality and specific causes of mortality in a general population.
Led by Dr Dariush Mozaffarian from Harvard School of Public Health (HSPH), the team reported that older adults who had the highest blood levels of the fatty acids found in fish lived, on average, 2.2 years longer than those with lower levels - adding that high levels
Mozaffarian and his team said increasing omega-3 levels may be able to lower their overall mortality risk by as much as 27% - and may have up to a 35% reduction in mortality risk from heart disease.
"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," said Mozaffarian.
"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,” he added.
"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.”
The research team examined 16 years of data from about 2,700 U.S. adults aged 65 or older who participated in the Cardiovascular Health Study (CHS) - a long-term study supported by the US National Heart, Lung, and Blood Institute.
Mozaffarian and his colleagues analysed the total proportion of blood omega-3 fatty acids - including DHA, EPA and DPA - in participants' blood sample, finding that the three fatty acids (both individually and combined) were associated with a significantly lower risk of mortality.
In particular, DHA (docosahexaenoic acid) was most strongly related to lower risk of coronary heart disease (CHD) death (40% lower risk), especially CHD death due to arrhythmias (electrical disturbances of the heart rhythm) (45% lower risk), the team noted.
Of the other fatty acids measured—eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA)—DPA was most strongly associated with lower risk of stroke death, and EPA most strongly linked with lower risk of nonfatal heart attack.
Overall, study participants with the highest levels of all three types of fatty acids had a 27% lower risk of total mortality due to all causes.