Harvard researchers report their finding of a lower nonfatal heart attack risk associated with increased blood plasma levels of the omega-3 fatty acids EPA and, DPA, an intermediary between EPA and DHA.
The researchers utilized data from 32,826 women who participated in the Nurses' Health Study between 1989 and 1990. Dietary questionnaires were filled in to estimate intake and blood samples were analyzed for omega-3 fatty acids EPA, DHA, DPA, and ALA levels in plasma and red blood cells.
Over six years of follow-up women whose plasma levels of EPA were among the highest 25 percent were found to have a 77 percent lower risk of suffering a heart attack than those whose levels were in the lowest quarter. Those whose DPA levels were highest experienced a 60 percent lower risk. Subjects with higher plasma concentrations of EPA, DHA, and DPA tended to have higher protective HDL cholesterol and lower triglyceride levels.
A protective effect against fatal coronary heart disease and sudden cardiac death has been linked with sufficient levels of omega-3 fatty acids in prior research. Their effect in nonfatal heart attack also had to be established and now it has been. "This prospective study provides new evidence that plasma concentrations of EPA and DPA are associated with a lower incidence of nonfatal heart attack among US women," the authors conclude. The study is published in the July 2008 issue of the American Journal of Clinical Nutrition.
The Japanese Paradox
Men in Japan have similar lifetime levels of cholesterol, and similar rates of both elevated blood pressure and type 2 diabetes as men in the U.S., and they are far more likely to smoke. So why is it that the rate of heart disease among men living in Japan is less than half that of men living in the U.S. and that Japanese men tend to have less atherosclerosis -- the artery-clogging plaque that leads to heart attacks and strokes?
A new study suggests that the answer is a lifetime’s inclusion of fish supplying fish oils in the diet. The men had high levels Omega-3 fish fatty acids because they ate more fish, men living in Japan who participated in the study had twice the levels of omega-3 fatty acids in their blood as white men and Japanese men living in the U.S. They also had less severe degrees of atherosclerosis.
The finding lends support to the hypothesis that omega-3 fatty acids, which are found primarily in fatty fish like mackerel, and salmon, protect against plaque buildup in the arteries. "The extremely high intake of fish in Japan may explain the much lower rate of atherosclerosis and subsequent coronary heart disease," researcher Akira Sekikawa, MD, PhD states in an interview. "This study does not prove that omega-3 is protecting these men, but we showed that artery thickness decreased as omega-3 levels went up."
The Japanese diet has become increasingly westernized since the end of World War II, but fish consumption in Japan is still among the highest in the world.
People in Japan eat an average of 3 ounces of fish every day, while the average American finds it difficult to manage the two servings of fish a week recommended for heart health by the American Heart Association, according to omega-3 researcher William Harris, PhD. He adds that the average omega-3 intake in Japan of 1 gram a day is about eight times higher than the amount the typical American gets. "We are not a nation that loves fish, and that isn't likely to change," he says. "But it is increasingly clear that we need to get more omega-3 into our diets." Fish oil supplements are one way of doing this. Studies in individuals with heart disease have shown a benefit of supplemental omega-3 fatty acids from Fish Oil Capsules. Based on these studies, the American Heart Association recommends that people with heart disease take 1 gram of EPA plus DHA daily. The study included 281 Japanese men living in Japan, an equal number of Japanese men living in the U.S., and 306 white men who lived in the U.S. All the men were in their 40s, and all underwent blood testing to determine serum levels of fatty acids, including omega-3. The men also had two tests for atherosclerosis -- one measuring the thickness of the artery wall in a major neck artery that sends blood to the brain and the other measuring plaque in arteries leading to the heart.
While total fatty acid levels were similar in the three groups, blood omega-3 levels in the Japanese men living in Japan were 45% higher and 80% higher, respectively, than in Japanese men and white men living in the U.S. Convincingly, both measures of atherosclerosis showed less plaque buildup in the arteries of the Japanese men living in Japan. Atherosclerosis levels were similar in both Japanese-Americans and in white Americans. "This indicates that much lower death rates from coronary heart disease in the Japanese in Japan is very unlikely due to genetic factors," Sekikawa says.
The study appears in the Aug. 5 issue of the Journal of the American College of Cardiology.
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