Study Counts Benefits Of Cutting Salt

A national program to reduce dietary salt could prevent tens of thousands of heart attacks, strokes and deaths and trim as much as $24 billion from the U.S. health-care tab, according to a study published Wednesday in the New England Journal of Medicine.

The study, a computer simulation, suggests the impact would be similar to prevention strategies such as quitting smoking, lowering cholesterol or modest weight-loss.

But significant cuts in salt from the diet could be challenging for individuals without action from food manufacturers. Some 75% of dietary salt intake comes from processed foods, according to the researchers.

Their findings add to a growing body of research suggesting that lowering dietary salt could be an effectiveweapon against high blood pressure and cardiovascular disease. 'The time is right now to consider efforts to . . . achieve population wide reduction in salt' intake, says Kirsten Bibbins-Domingo, first author of the study and an associate professor of medicine and epidemiology at the University of California, San Francisco.

Morton Satin, technicaldirector of the Salt Institute, a nonprofit group of salt producers, says few data exist linking salt intake and disease. He is skeptical that reducing salt will yield important health benefits.

Americans consume far more than the recommended daily salt intake. The average adult male consumes more than 10 grams of salt a day, according to the U.S. National Health and Nutrition Examination Survey. On Wednesday, the American Heart Association published new guidelines calling for all Americans to reduce their daily intake of sodium -- a key component of salt -- to 1,500 milligrams, equivalent to 3.8 grams of salt. Previously, that was the recommended limit for higher risk individuals; the regular limit had been 2,300 milligrams of sodium, or 5.8 grams of salt.

In the computer simulation, which included data from the U.S. Census, the Centers for Disease Control and Prevention and other national studies, Dr. Bibbins-Domingo and her colleagues estimated the effect of lowering salt in the daily American diet by a small amount -- up to three grams a day -- in adults age 35 and older.

Based on other research, they assumed a three-gram reduction in salt would lower systolic blood pressure by 3.6 to 5.6 millimeters of mercury; a one-gram reduction would reduce the level by 1.2 to 1.9 millimeters. (Systolic is the higher number in a blood-pressurereading. People whose level is 140/90 or more are considered to have high blood pressure.) Such modest blood-pressurereductions are associated, in other studies, with significant lowering of risk of death, heart attack and stroke.

In the current study, researchers found that lowering salt intake by three grams a day would cut new cases of heart disease annually by a third -- an estimated 60,000 to 120,000 cases per year -- heart attacks by 54,000 to 99,000 cases and strokes by 32,000 to 66,000 cases. It would reduce about 100,000 deaths a year in the U.S.

《新英格兰医学杂志》（New England Journal of Medicine）1月20日刊登的一篇研究称，一项旨在降低饮食中盐摄入量的国家项目将减少数以万计的心脏病发作、中风和死亡病例，并使美国的国民医疗费用降低240亿美元。

这项运用了电脑模拟的研究显示，这种影响类似于戒烟、降低胆固醇或适度减肥等预防性策略的影响。

但是，如果食品生产企业不行动起来，仅靠个人很难做到显著降低饮食中的盐摄入量。研究人员称，饮食中约75%的盐摄入量来自于加工食品。

有越来越多的研究都表明降低饮食中的盐摄入量是对抗高血压和心血管疾病的有效武器，这项成果进一步充实了这些研究。"在全社会范围内展开降低盐摄入量的行动......现在正是时候"，这项研究的第一作者、加利福尼亚大学旧金山分校（University of California）的医学与流行病学副教授柯尔斯滕•比宾斯-多明戈（Kirsten Bibbins-Domingo）说。

美国盐业协会（Salt Institute，一家由盐类生产商组成的非赢利组织）的技术总监莫顿•萨坦（Morton Satin）称，几乎没有数据显示盐摄入量与疾病之间存在联系。他对降低盐摄入量明显有益于健康表示怀疑。

美国人的每日盐摄入量远远高于建议每日盐摄入量。据《美国国民健康与营养调查》（U.S. National Health and Nutrition Examination Survey.）显示，一名普通美国成年男性一天摄入的盐超过10克。1月20日，美国心脏协会（American Heart Association）公布了新的指引，呼吁所有美国人将每日的钠摄入量──钠是盐的主要成份──降至1,500毫克，相当于3.8克盐。以前，这是高风险人群的建议摄入限量；常规摄入限量原本为2,300毫克钠，或5.8毫克盐。

在包括来自美国人口普查、疾病控制与预防中心和其它全国性研究的数据的电脑模拟中，比宾斯-多明戈博士和她的同事们估计了小幅降低美国人每日盐摄入量──每日最高降低3毫克──对35岁及35岁以上成人的影响。

根据其它研究，他们假设减少3毫克的盐摄入量将降低3.6至5.6毫米汞柱的收缩压；减少1毫克的盐摄入量将降低1.2至1.9毫米汞柱的收缩压。（收缩压是血压读数的较高值。血压水平为140/90或更高的人被认为患有高血压。）其它研究发现，这种适度的血压降低与死亡、心脏病发作和中风风险的显著降低相关。

在目前的研究中，研究人员发现，每天降低3克盐摄入量，将使每年的新增心脏病病例降低三分之一，估计可减少60,000宗至 120,000宗病例；使心脏病发作病例减少54,000至99,000宗；使中风病例减少32,000至66,000宗。这一做法还将使美国每年减少约 100,000宗死亡病例。

Shirley S. Wang