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September 9, 2008 |
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The September, 2008 issue of the American Journal of Clinical Nutrition published the results of a Norwegian study which found an increased risk of dying among older hospital patients with low plasma concentrations of eicosapentaenoic acid (EPA), a polyunsaturated omega-3 fatty acid that is present in relatively high amounts in oily fish.
The study included 254 frail patients with an average age of 82.1 who were admitted to St Olavs Hospital in central Norway. Blood samples were analyzed for numerous factors and phospholipid fatty acid concentrations were measured in plasma. Eicosapentaenoic acid levels were used as a marker for marine fatty acid status. The patients were followed for three years, during which any deaths were recorded.
Participants whose plasma EPA levels were in the top 75 percent of participants averaged nearly half the risk of dying from all causes compared with those whose levels were in the lowest 25 percent. Cardiovascular disease was the major cause of death in both groups, yet was responsible for a greater percentage of deaths among those whose EPA levels were lowest. Other major causes of death included infection, cancer and stroke.
The authors remark that several mechanisms of action have been proposed for omega-3 fatty acids’ benefits, including an antiarrhythmic property and platelet activity modulation, which reduce the risk of fatal cardiac arrest, as well as an ability to reduce blood clots, heart rate, and plasma lipids.
In an accompanying editorial, William S. Harris of Sanford Research in Sioux Falls, Idaho notes that current research findings suggest that long term intake of increased amounts of omega-3 fatty acids may provide specific health benefits that short-term supplementation cannot. He observes that Norwegians typically consume approximately one gram of omega-3 fatty acids per day: an amount that is much higher than the average intake of individuals residing in the United States, which could make the lowest intake group in the current study similar to those with the highest intake in the U.S
“The results suggest that a moderate dietary intake of omega-3 fatty acids in the elderly reduces their overall mortality if they become acutely ill and hospitalized,” the study’s authors conclude. “The results also suggest that approximately 25 percent of this Norwegian population might have benefited from an increased dietary intake before the acute incident.” |
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The main fatty acid in the Western diet is linoleic acid, found mostly in vegetable oils. However, epidemiologic studies many years ago showed that people with a high intake of fatty fish, like the Japanese, have less cardiovascular disease than those who consume Western-type diets (Lee KW et al 2003). Fatty fish, such as mackerel, salmon, herring, sardines, and albacore tuna, and their oils are good sources of long-chain omega-3 polyunsaturated fatty acids (Calder PC et al 2002). The most important omega-3 fatty acids are eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), which when ingested are immediately available for use in the body.
Extensive scientific studies, both animal and human, have shown that supplementing the diet with fish and their oils has a beneficial effect on the heart, particularly in preventing cardiac arrhythmias (Nair SS et al 1997). The omega-3 fatty acids in fish oils appear to stabilize the electrical activity of the heart muscle, reducing susceptibility even to ventricular arrhythmias and ultimately decreasing the risk of sudden cardiac death (Lee KW et al 2003; Kang JX et al 2000).
The GISSI-Prevention study of more than 11,000 people taking a purified form of omega-3 fatty acids as a supplement has shown a significant decrease in the occurrence of sudden cardiac death among the participants (Lee KW et al 2003; De Caterina R et al 2002; Richter WO 2003). The efficacy of this preparation was greater than that of pravastatin, a commonly prescribed statin drug. Remarkably, the reduction in fatalities was seen even in patients who were already taking preventive medications such as aspirin and statin drugs (Lee KW et al 2003; Richter WO 2003). Beneficial effects may be seen within 90 days of starting omega-3 therapy and may continue progressively with longer use, leading to their recommendation as a “promising additional measure for secondary prevention” (Richter WO 2003). |
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