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【medical-news】ω-3脂肪酸相比于遗传因素对于心血
The study, published in the August 5, 2008 issue of the Journal of the American College of Cardiology (available online July 28), was conducted by a group led by Dr Akira Sekikawa (University of Pittsburgh, PA, and Shiga University of Medical Science, Japan).
They found that compared with white or Japanese American men living in the US, Japanese men living in Japan had twice the blood levels of omega-3 fatty acids — a finding that was independently linked to low levels of atherosclerosis.
"The death rate from coronary heart disease in Japan has always been puzzlingly low. Our study suggests that the very low rates of coronary heart disease among Japanese living in Japan may be due to their lifelong high consumption of fish," Sekikawa said.
The researchers note that coronary heart disease (CHD) mortality in Japan has been decreasing since the 1970s, despite the changes in lifestyle toward Westernization that have brought a continuous increase in dietary fat intake and serum cholesterol. They point out that recent studies in Japan, where fish intake is one of the highest in the world, showed that additional supplementation or intake of marine-derived omega-3 fatty acids is significantly associated with a reduced risk of nonfatal coronary events. They thus conducted the current study to investigate whether greater levels of serum marine-derived omega-3 fatty acids in Japanese men vs white men are associated with lower levels of atherosclerosis.
The study, known as Electron-Beam Tomography, Risk Factor Assessment Among Japanese and US Men in the Post-World War II Birth Cohort (ERA JUMP) included 868 randomly selected men aged 40 to 49. Of these, 281 were Japanese men living in Japan; 306 were white men living in the US, and 281 were third- or fourth-generation Japanese American men from Hawaii. All study participants had a physical examination, completed a lifestyle questionnaire, and had blood tests to measure cholesterol levels and levels of omega-3 fatty acids. Atherosclerosis was assessed by measuring carotid intima-medial thickness (IMT) and coronary artery calcification (CAC).
Results showed that the Japanese men had the lowest levels of atherosclerosis, whereas whites and Japanese Americans had similar higher levels. The Japanese men also had twofold higher levels of marine-derived omega-3 fatty acids than white and Japanese Americans.
Levels of atherosclerosis and omega-3 fatty acid intake in Japanese vs American men Measure Japanese men White American men Japanese American men
Prevalence of CAC (%) 9.3 26.1 31.4
Mean carotid IMT (µm) 614 670 720
Omega-3 fatty acids (% of total fatty acids) 9.2 3.9 4.8
In addition, the significant differences between Japanese and American men in multivariable-adjusted IMT and CAC prevalence became nonsignificant after adjustment further for marine-derived omega-3 fatty acids.
The researchers say: "Our results suggest that marine-derived omega-3 fatty acids have antiatherogenic effects, especially at the high levels observed in Japanese men," a hypothesis they note is supported by two recent Japanese studies. The Japan Eicosapentaenoic Acid Lipid Interventions Study (JELIS) randomized trial showed a reduced CHD rate with eicosapentaenoic acid (EPA), and the Japan Public Health Center-Based (JPHC) study, a 10-year prospective cohort study of 41,578 middle-aged Japanese subjects, showed significant inverse associations between dietary intake of marine-derived omega-3 fatty acids and nonfatal coronary events.
They point out that in the current study, Japanese American men had similar or greater levels of atherosclerosis compared with US white men, a finding that they say was unexpected and was still apparent after they excluded those with diabetes, those with hypertension, and those taking lipid-lowering medications, indicating that the low atherosclerosis in Japanese men is unlikely to be primarily a result of genetic factors.
"Our findings indicate that the antiatherogenic effect of marine-derived omega-3 fatty acids is likely to be present only in populations with fish intake well above those of most Western populations. It thus appears unlikely that short-term supplementation in a low-fish-intake population would show such a relationship," Sekikawa et al comment.
They conclude: "If the high intake of marine-derived omega-3 fatty acids in Japanese men is the primary reason for their extremely low CHD mortality in the face of high traditional cardiovascular risk factors, dietary interventions to increase marine-derived omega-3 fatty acids in the US and other countries where fish intake is not as high as in Japan could have a very substantial impact on CHD."
The Japanese factor
In an accompanying editorial [2], Dr William Harris (Sanford Research/University of South Dakota [USD], Metabolism and Nutrition Research Center, Sioux Falls, South Dakota) notes that with the adoption of a more Western lifestyle, Japanese men have been found to have similar lifetime cholesterol and blood-pressure levels as white men in the US, along with a greater rate of smoking and prevalence of diabetes, but CHD rates in Japan remain less than one-half of those in the US. "This unexpected finding has stimulated the search for a factor or factors in the Japanese diet or lifestyle that have the power to withstand the onslaught of advancing risk factors," Harris comments, adding that the results of the current study add weight to the idea that omega-3 fatty acids could be that factor.
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作者:admin@医学,生命科学 2011-06-03 05:14
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