A new study from the Harvard School of Public Health and the University of Washington has confirmed that regular consumption of fish reduces by a quarter the risk of premature death for an elderly person, and by a third the risk of dying from cardiovascular disease. Indeed, researchers found that elderly individuals with the highest blood levels of marine omega-3 fatty acids lived, on average, 2.2 years longer than those with lower levels. "Although fish consumption has long been considered part of a healthy diet, few studies have compared blood omega-3 levels with mortality in older adults," said the lead author of the study, Dariush Mozaffarian, associate professor in the Department of Epidemiology at Harvard, in a press release. "Our findings confirm the importance of high blood levels of omega-3s for cardiovascular health and suggest that as people age, these high levels of omega-3s may extend life years."
Researchers have long linked the consumption of unsaturated fats from fish with a reduced risk of heart disease. Most national and international health authorities therefore recommend eating fish - especially fatty fish - at least twice a week. However, this is the first time researchers have linked fish consumption levels and mortality rates. In their study, researchers examined 16 years of data from 2,700 healthy American adults aged 65 and older who participated in the Cardiovascular Health Study (CHS). They also analyzed the total proportion of omega-3 fatty acid blood levels in the blood samples of study participants. After adjusting the data for diet and lifestyle and other factors, they concluded that omega-3 fatty acids were associated with a significantly lower risk of mortality.
DHA and DPA
One particular fatty acid - docosahexaenoic acid (DHA) - was associated with a 40 percent lower risk of death from coronary heart disease. When comparing eicosapentaenoic acid (EPA) and docosapentaenoic acid (DPA), it appears that DPA is more strongly associated with a lower risk of death from stroke, and that EPA is more effective in reducing the risk of nonfatal myocardial infarction. Docosapentaenoic acid (DPA) is an omega-3 fatty acid found mainly in fish, fish oils, and red meat. Unlike EPA and DHA, DPA has not been widely researched. However, available scientific literature suggests that DPA may have beneficial effects on health.
Overall, participants with the highest blood levels of each of the three types of fatty acids had a 27 percent lower risk of total mortality (all causes combined). When researchers examined how omega-3 fatty acid consumption affected omega-3 blood levels, they found that the latter had an impact on blood levels for individuals transitioning from a low omega-3 diet to a 400 mg per day intake. Beyond 400 mg, blood levels increased more gradually.
"The results suggest that the most beneficial omega-3 intake would be equivalent to two servings of fatty fish per week," Mozaffarian said. Among the fish containing high levels of omega-3 fatty acids are mackerel, trout, tuna, salmon, herring, sardines, and anchovies.
Sources: Harvard School of Public Health.
References: (1) Plasma Phospholipid Long-Chain Omega-3 Fatty Acids and Total and Cause-Specific Mortality in Older Adults. Dariush Mozaffarian, Rozenn N. Lemaitre, Irena B. King, Xiaoling Song, Hongyan Huang, Molin Wang, Frank M. Sacks, Eric B. Rimm, and David S. Siscovick, Annals of Internal Medicine, online April 1, 2013. (2) The Cardiovascular Health Study. (3) Omega-3 Docosapentaenoic Acid (DPA): What is known?