Higher omega-3 levels linked with lower risk of dying over a 16 year period

Friday, April 5, 2013. The April 2, 2013 issue of the Annals of Internal Medicine reports the finding of a study of older U.S. adults which uncovered a protective effect for high plasma phospholipid omega-3 polyunsaturated fatty acids against the risk of dying over 16 years of follow-up. Omega-3 fatty acids are abundant in oily fish, and have been linked with a variety of health benefits, including a lower risk of cardiovascular disease.

The study included 2,692 men and women aged 65 years or older upon enrollment in the Cardiovascular Health Study between 1989 and 1993. Dietary questionnaire responses were analyzed for eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) intake. Blood samples obtained during 1992-1993 were analyzed for plasma phospholipid EPA, DHA and docosapentaenoic acid (DPA). Over sixteen years of follow-up, 1,625 deaths occurred, including 359 caused by coronary heart disease (CHD) and 130 resulting from stroke.

Men and women whose total omega-3 fatty acids were among the top one-fifth of participants had a 27% lower risk of dying over follow-up than those whose levels were among the lowest fifth. When omega-3 fatty acids were individually analyzed, those among the top fifth of EPA, DPA and DHA levels were found to have a 17%, 23% and 20% lower risk. The risk of dying of heart disease was 35% less among those whose total omega-3 levels were highest, and arrhythmic cardiac deaths were lowered by 48%. On average, having an omega-3 fatty acid level among the top fifth conferred 2.2 extra years of life in comparison with subjects whose level was lowest.

When the relationship between omega-3 fatty acid intake and plasma levels was examined, the largest effect was seen with an intake of up to 400 milligrams per day. "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," commented lead author Dariush Mozaffarian, who is an associate professor in the Department of Epidemiology at Harvard School of Public Health.

"No controlled trials have reported effects of omega-3 polyunsaturated fatty acids on total mortality in generally healthy populations; 1 primary prevention trial is enrolling," Dr Mozaffarian and colleagues observe. "Adding a supplement to background consumption of approximately 150 mg of EPA plus DHA per day (the approximate mean consumption in the United States and many European countries) would be calculated, on the basis of nonlinear effects in observational studies, to produce a reduction in CHD mortality of approximately 15%. In comparison, increasing from a baseline of low intake to at least moderate consumption (greater than 250 milligrams per day)—or similarly, as in our present investigation, comparing low and high circulating levels—would be predicted to have larger benefits, consistent with our observations."

"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," Dr Mozaffarian remarked. "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."