|
No Benefit Seen in Sharp Limits on Salt in Diet In a report that undercuts years of public health warnings, a prestigious group convened by the government says there is no good reason based on health outcomes for many Americans to drive their sodium consumption down to the very low levels recommended in national dietary guidelines. 一个有名望的专家组提交的一份报告，削弱了一条公共健康领域多年来的警告。这个由政府召集的专家组说，从健康后果来看，没有好的理由要求许多美国人把钠摄入量降到极低的水平，也就是全国膳食指南建议的水平。 Those levels, 1,500 milligrams of sodium a day, or a little more than half a teaspoon of salt, were supposed to prevent heart attacks and strokes in people at risk, including anyone older than 50, blacks and people with high blood pressure, diabetes or chronic kidney disease — groups that make up more than half of the American population. 这个极低的摄入量，即每天食用不超过1500毫克的钠(相当于略多于半茶匙的盐)，曾被认为能在高危人群中预防心脏病发作或中风，所谓的高危人群占美国人口的一半以上，包括所有50岁以上的人，黑人以及高血压、糖尿病或慢性肾病患者。 Some influential organizations, including the American Heart Association, have said that everyone, not just those at risk, should aim for that very low sodium level. The heart association reaffirmed that position in an interview with its spokesman on Monday, even in light of the new report. 包括美国心脏协会(American Heart Association)在内的一些权威组织曾表示，不仅是高危人口，所有的人都应该以这个极低的钠摄入量为目标。尽管新报告已经出来，心脏协会发言人在周一接受采访时仍重申了这一立场。 But the new expert committee, commissioned by the Institute of Medicine at the behest of the Centers for Disease Control and Prevention, said there was no rationale for anyone to aim for sodium levels below 2,300 milligrams a day. The group examined new evidence that had emerged since the last such report was issued, in 2005. 然而，这个国家医学院(Institute of Medicine)在疾病控制和预防中心(Centers for Disease Control and Prevention)要求下委任的新专家委员会表示，没有理由要求任何人把每天的钠摄入量目标定在低于2300毫克以下的水平。上次发布类似的报告是在2005年，该委员会考察了那之后出现的新证据。 “As you go below the 2,300 mark, there is an absence of data in terms of benefit and there begin to be suggestions in subgroup populations about potential harms,” said Dr. Brian L. Strom, chairman of the committee and a professor of public health at the University of Pennsylvania. He explained that the possible harms included increased rates of heart attacks and an increased risk of death. 委员会主席、宾夕法尼亚大学公共卫生教授布莱恩·L·斯特罗姆(Brian L. Strom)说，“当摄入量降低到2300这条线以下之后，有关益处的数据没有了，反而出现了对某些人口子群有潜在危害的提示。”他解释说，潜在危害包括心脏病发作的风险增加以及死亡的风险增加。 The committee was not asked to specify an optimal amount of sodium and did not make any recommendations about how much people should consume. Dr. Strom said people should not eat too much salt, but he also said that the data on the health effects of sodium were too inconsistent for the committee to say what the upper limit of sodium consumption should be. 委员会没有被要求指明钠摄入量的最佳值，因此没有对人该吃多少盐给出任何建议。斯特罗姆说人们不应该吃太多盐，但同时他还说，钠对人体健康影响的数据有很多矛盾，所以委员会无法给出一个钠摄入量的上限。 Until about 2006, almost all studies on salt and health outcomes relied on the well-known fact that blood pressure can drop slightly when people eat less salt. From that, and from other studies linking blood pressure to risks of heart attacks and strokes, researchers created models showing how many lives could be saved if people ate less salt. 直到大约2006年，几乎所有关于盐与健康后果的研究都基于一个众所周知的事实，即人们减少食盐量时，血压会略有降低。从这点出发，加上其他把血压与心脏病发作和中风的风险联系起来的研究，研究人员建立了模型，来揭示如果人们少吃盐可能挽救多少个生命。 The United States dietary guidelines, based on the 2005 Institute of Medicine report, recommend that the general population aim for sodium levels of 1,500 to 2,300 milligrams a day because those levels will not raise blood pressure. The average sodium consumption in the United States, and around the world, is about 3,400 milligrams a day, according to the Institute of Medicine — an amount that has not changed in decades. 美国现行的膳食指南，以国家医学院2005年的报告为根据，建议普通人群把每天的钠摄入量限制在1500至2300毫克，因为这些摄入量不会使血压升高。国家医学院表示，美国及世界各地每日的钠摄入量都差不多是3400毫克，几十年来都没有变化。 But more recently, researchers began looking at the actual consequences of various levels of salt consumption, as found in rates of heart attacks, strokes and death, not just blood pressure readings. Some of what they found was troubling. 然而最近，研究人员开始观察不同的盐摄入量的实际后果，比如心脏病发生率、中风及死亡率，而不仅仅是血压读数。其中一些发现令人不安。 One 2008 study the committee examined, for example, randomly assigned 232 Italian patients with aggressively treated moderate to severe congestive heart failure to consume either 2,760 or 1,840 milligrams of sodium a day, but otherwise to consume the same diet. Those consuming the lower level of sodium had more than three times the number of hospital readmissions — 30 as compared with 9 in the higher-salt group — and more than twice as many deaths — 15 as compared with 6 in the higher-salt group. 例如，该委员会考察了一项2008年的研究，该研究对象是232名意大利患者，他们都曾接受中度或严重充血性心力衰竭的积极治疗，研究人员将患者随机分为两个组，一组每日摄入2760毫克钠，另一组每日摄入1840毫克钠，其他的饮食都一样。钠摄入量更低的患者组与钠摄入量较高的患者组相比，前者中有30人再次住院，是后者中再次住院人数的三倍多，后者中有9人再次住院；前者中的死亡率是后者中的两倍多：前者中15人死亡，而盐摄入量较高的组中只有6人死亡。 Another study, published in 2011, followed 28,800 subjects with high blood pressure ages 55 and older for 4.7 years and analyzed their sodium consumption by urinalysis. The researchers reported that the risks of heart attacks, strokes, congestive heart failure and death from heart disease increased significantly for those consuming more than 7,000 milligrams of sodium a day and for those consuming fewer than 3,000 milligrams of sodium a day. 发表于2011年的另一项研究，对2.88万名55岁及以上的高血压患者进行了4.7年的跟踪调查，通过尿液检查分析了他们的钠摄入量。研究人员发现那些每天钠摄入量超过7000毫克的人，以及钠摄入量低于3000毫克的人，心脏病发作、中风、充血性心力衰竭的风险，及心脏病致死的风险大幅增加。 There are physiological consequences of consuming little sodium, said Dr. Michael H. Alderman, a dietary sodium expert at Albert Einstein College of Medicine who was not a member of the committee. As sodium levels plunge, triglyceride levels increase, insulin resistance increases, and the activity of the sympathetic nervous system increases. Each of these factors can increase the risk of heart disease. 阿尔伯特·爱因斯坦医学院(Albert Einstein College of Medicine)膳食钠专家迈克尔·H·奥尔德曼(Michael H. Alderman)表示，钠摄入过低是有生理后果的。奥尔德曼不是专家委员会的成员。随着钠摄入量的骤减，人体甘油三脂含量增加，抗胰岛素性增加，交感神经系统的活动也会增加。这些因素中的每一个都会增加心脏病的风险。 “Those are all bad things,” Dr. Alderman said. “A health effect can’t be predicted by looking at one physiological consequence. There has to be a net effect.” “这些都不是好东西，”奥德尔曼说，“只看一个生理后果不能预测健康效应。需要看净效应。” Medical and public health experts responded to the new assessment of the evidence with elation or concern, depending on where they stand in the salt debates. 对有关食盐与健康证据的新评估，医疗及公共卫生专家中有人得意洋洋，有人忧心忡忡，这要看他们在盐争议上的立场。 “What they have done is earth-shattering,” Dr. Alderman said. “They have changed the paradigm of this issue. Until now it was all about blood pressure. Now they say it is more complicated.” The report, he predicted, “will have a big impact.” 奥德尔曼说，“专家组的新评估意义极其重大。他们改变了看待这个问题的框架。以前都是从血压的角度看问题。现在他们说，问题更为复杂。”他预计该报告“将会产生重大影响”。 But Bonnie Liebman, director of nutrition at the Center for Science in the Public Interest, an advocacy group that has taken a strong position against excessive salt consumption, worried that the public would get the wrong message. 但是，来自一个倡导组织的邦尼·利布曼(Bonnie Liebman)反对过量摄入食盐的立场强硬，利布曼是符合公共利益的科学中心(Center for Science in the Public Interest)营养部主任，她担心公众将从新报告中得到错误的信息。 “It would be a shame if this report convinced people that salt doesn’t matter,” Ms. Liebman said. 利布曼说，“如果这个报告让人们相信吃多少盐都没关系，那将是一个耻辱。” The American Heart Association agrees with her. Dr. Elliott Antman, a spokesman for the association and a professor of medicine at Brigham and Women’s Hospital n Boston, said the association remained concerned about the large amount of sodium in processed foods, which makes it almost impossible for most Americans to cut back. People should aim for 1,500 milligrams of sodium a day, he said. 美国心脏协会同意她的观点。协会发言人、波士顿布莱根妇女医院(Brigham and Women's Hospital)医学教授埃利奥特·安特曼(Elliott Antman)表示，协会仍对那些钠含量很高的加工食品感到担忧，这些食品使大多数美国人几乎无法减少钠的摄入量。他表示，人们每日的钠摄入量应为1500毫克。 “The American Heart Association is not changing its position,” Dr. Antman said. The association rejects the Institute of Medicine’s conclusions because the studies on which they were based had methodological flaws, he said. The heart association’s advice to consume 1,500 milligrams of sodium a day, he added, is based on epidemiological data and studies that assessed the effects of sodium consumption on blood pressure. 安特曼说，“美国心脏协会将不改变自己的立场。”他表示，该协会拒绝接受国家医学院的结论，因为结论所基于的研究使用的方法有缺陷。他补充说，心脏协会建议每天摄入1500毫克的钠，这是基于流行病学数据和一些评估钠对血压影响的研究提出来的。 The Institute of Medicine committee said it was well aware of flaws in many of the studies of sodium, especially ones that the previous Institute of Medicine committee relied on for its 2005 recommendations. Much of that earlier research, committee members said, looked for correlations between what people ate and their health. But people with different diets can differ in many ways that are hard to account for — for example, the amount of exercise they get. And relying on people’s recall of how much salt they consumed can be unreliable. 国家医学院的委员会表示，他们非常清楚很多有关钠的研究存在缺陷，尤其是医学院2005年提出建议时所参考的那些研究。委员会成员表示，很多以前的研究寻找的是人的膳食与健康之间的关联。然而，膳食不同的人可能在很多方面都不同，而这些不同在研究中很难考虑到，比如，他们的运动量。依赖人们自己回忆每天吃多少盐是靠不住的。 |
|
|
