Omega-3脂肪酸保护心脏

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March 29, 2007 -- An omega-3 fatty acid found in fish oil may help prevent nonfatal heart problems in some people with high cholesterol, a Japanese study shows.

The omega-3 fatty acid is called EPA (eicosapentaenoic acid). It's found in fish such as salmon and mackerel, along with another fatty acid called DHA (docosahexaenoic acid).

The Japanese study looked at more than 18,600 adults with high cholesterol, including 3,660 people with a history of coronary artery disease.

The coronary arteries supply blood to heart muscle. Unhealthy coronary arteries make heart attacks more likely, and high cholesterol is a risk factor for coronary artery disease.

Study participants were followed for more than four years, on average. During that time, they all took cholesterol-lowering statin drugs.

The researchers assigned half the participants to also take pills containing highly purified EPA. For comparison, the other participants only took their statins, with no EPA pills.

Then the researchers tracked major coronary events, such as sudden cardiac death, fatal or nonfatal heart attack, or other nonfatal heart problems, in both groups for 4.6 years, on average.

EPA Advantage
During the study, the vast majority of patients had no major heart problems.

However, 2.8% of those taking EPA along with statins experienced a major coronary event, compared with 3.5% of those only taking statins.

That's a 19% difference, note the researchers, who included Mitsuhiro Yokoyama, MD, of Kobe University in Kobe, Japan.

EPA pills weren't linked to any difference in fatal heart attacks or sudden cardiac death.

When Yokoyama's team took a closer look at the data, they found the EPA advantage only applied to patients with a known history of coronary artery disease.

Patients with high cholesterol but no history of coronary artery disease may also get some heart protection from EPA, but that's not certain, since so few of them had major heart problems during the study.

The researchers conclude that EPA is a \"promising treatment\" for the prevention of heart problems in Japanese patients with high cholesterol.

Study's Limits
Fish is a staple of the traditional Japanese diet. That may partly explain why EPA pills didn't seem to curb fatal heart events. \"Our patients could possibly all have had intakes of fish that were above the threshold for prevention of fatal coronary events or sudden cardiac death,\" write Yokoyama and colleagues.

The researchers didn't ask patients about their diets.

Yokoyama's team also warns that the findings might not apply to people who don't eat lots of fish. \"EPA might affect risk only at very high levels of fish intake, such as those common in Japan,\" they write.

Lastly, the researchers note that they only tested EPA pills, not fish or fish oil. The pills were made in Japan by Mochida Pharmaceutical Co., which funded the study.

Curbing Heart Problems
The study appears in The Lancet, along with an editorial by Dariush Mozaffarian, MD, MPH, DrPH, of the Harvard School of Public Health.

Mozaffarian points out that the study didn't include a group taking an inactive pill (placebo) along with their statins.

Still, the drop in nonfatal heart events in those taking EPA and statins \"should not necessarily be discounted,\" writes Mozaffarian.

He commends the Japanese researchers for their work and calls for further studies.

Mozaffarian takes a back-to-basics approach to preventing heart problems. For instance, he notes in his editorial that modest dietary changes are less risky, less costly, and more accessible than drugs, invasive procedures, or devices.

\"We must curb our infatuation with downstream risk factors and treatments, and focus on the fundamental risk factors for cardiovascular disease: dietary habits, smoking, and physical activity,\" writes Mozaffarian.
200年3月29日 一项日本研究表明，在鱼油中发现的一种Omega－3脂肪酸可以帮助预防高胆固醇人群的非致命性心脏病。这种Omega－3脂肪酸是二十碳五烯酸，英文缩写为EPA。EPA和DHA一起在大马哈鱼和鲭鱼中被发现。日本的研究考察了18600高胆固醇的成年人，包括3600位具有冠心病史的患者。冠状动脉给心脏肌肉供给血液。不健康的冠状动脉会导致心脏病发作，高胆固醇是冠状动脉疾病的危险因子。研究参与人员平均随访时间是4年。在此期间，他们都服用他汀类降血脂药物。研究人员将受试者分组，一半受试者服用他汀类药物以及高纯度的EPA片剂，另一半受试者只服用他汀类药物。研究者追踪主要的冠心病事件，包括心脏猝死，致命或者非致命性心脏病，以及其它非致命性心脏问题。在两组的平均追踪时间是4.6年。

EPA优势
在研究中，大部分病人没有发生心脏问题。但是，在服用EPA和他汀类药物的人群中冠心病发病率是2.8％，而只服用他汀类药物的人群冠心病发病率是3.5％。日本神户大学的医学博士横山光博指出，这两个发病率之间有19％的差异。 EPA片剂与致命性心脏病发作和心脏猝死之间没有联系。当横山光博研究团队对数据进行进一步分析发现，EPA作用只是在已有冠心病历史的病人中体现。高胆固醇但是没有冠心病史的病人也可能从EPA中得到心脏保护作用，但是这一点并没有被确认，因为研究期间这些人很少发生心脏病。研究者得出结论，EPA是一种很有希望的治疗方法，可以有效预防高胆固醇日本病人的心脏病发作。

研究局限
鱼类是日本传统饮食的一个主要组成成分。这可以部分解释为什么EPA不能抑制致命性心脏病事件。横山光博及其同事写到：“我们的病人可能已经食用了足够的鱼类，其中所含的EPA已经超过了预防致命性心脏事件和心脏猝死的阈值。”研究人员并没有考察病人的饮食情况。横山光博研究团队同时警告说这一发现可能不适用于那些日常饮食不食用大量鱼类的人群。“EPA可能影响那些象日本人一样大量食用鱼类的人群。”最后，研究者写到他们只试验了EPA片剂，而不是鱼或者鱼油。EPA片剂由日本持田制药有限公司生产，这一研究也是由该公司资助进行。

抑制心脏问题
这一研究发布在《柳叶刀》杂志上，同时刊登了哈佛大学公共卫生学院医学博士，公共卫生硕士，公共卫生博士Dariush Mozaffarian的一篇主编评论。 Mozaffarian指出该研究没有包含一组服用他汀类药物和安慰剂的对照组。 Mozaffarian还指出，服用EPA和他汀类药物从而使非致命性心脏病发作降低的作用不应该被忽视。他赞扬了日本研究者的工作并期望进一步的研究。 Mozaffarian采用了反璞归真的方法来预防心脏病。例如，他在编辑评论中说，适度的改变饮食结构比药物、入侵程序或者设备更加低风险、低成本和易于接收。Mozaffarian写到，我们应该停止醉心于研究下游危险因子和治疗方法，并关注心血管疾病的基本危险因子：饮食习惯，吸烟和体育活动.