It's 2009 -- several decades after health officials began urging Americans to cut down on salt.

Do you know how much you're consuming?

If you're a typical American, it's about 3,400 milligrams of sodium per day. That's well beyond the 2,300 mg recommended by the U.S. Dietary Guidelines. And it's 15 times as much as the human body requires.

Average sodium intake has increased about 50% since the 1970s, largely because we're eating more convenience foods. And as makers of processed food have cut down on fat and sugar, they've often added more salt.

But all this sodium can be bad for your health.

Excess salt has been linked to osteoporosis, kidney damage and stomach cancer. Worse, it raises blood pressure, a key factor in heart attacks and strokes, which kill about 850,000 Americans a year.

'After smoking, high blood pressure is the leading cause of preventable illness and death,' says New York City Health Commissioner Thomas Frieden, who is urging makers of packaged foods and restaurants nationwide to gradually reduce their sodium content by 50% over the next 10 years. The Centers for Disease Control and Prevention estimates that such a reduction could save 150,000 lives and $10 billion in health-care expenditures a year.

Some 50 million Americans have hypertension (that is, blood pressure readings consistently at or above 140/90 mm/Hg). Another 20 million are prehypertensive (with blood pressure from 120/80 to 139/ 89 mm/Hg). Hypertension is more common among African-Americans than whites, and nearly 90% of Americans eventually develop it as they age.

With that in mind, the CDC is urging anyone who has hypertension, is African-American or over age 40 -- nearly 70% of the U.S. population -- to follow a stricter guideline of just 1,500 mgs a day.

About 80% of Americans' salt intake comes from processed foods and restaurant meals; only 20% comes from salt used in home cooking and added at the table. But cutting salt from processed food isn't easy. Besides enhancing taste, salt helps provide texture to many foods and acts as a preservative. And Americans have become accustomed to the taste.

The Grocery Manufacturers Association, which represents food makers, says many of its members have cut sodium in their products and introduced lower-salt items in recent years. But it believes that any government effort needs to include consumer education and scientific research as well.

A few critics don't think a broad reduction in sodium is warranted. Michael Alderman, a professor of medicine and public health at Albert Einstein College of Medicine in Bronx, N.Y., says it hasn't been conclusively shown that cutting salt intake across the population would save lives, and it could have unintended consequences. Lowering salt can cause kidney problems and contribute to insulin resistance in some cases, says Dr. Alderman, who is an unpaid consultant to the Salt Institute, an industry group.

Darwin Labarthe, director of the CDC's Division for Heart Disease and Stroke Prevention, counters that there's a very broad consensus that reducing salt would cut the risk of heart attacks and strokes, and there is little evidence of harmful effects. The American Heart Association, the American Medical Association and the World Health Organization all urge lower salt consumption.

What can you do about your own salt intake? It's impossible to know for sure how much you're consuming. Even raw chicken in the grocery store is sometimes 'enhanced' with salt water to make it plumper (and heavier, and thus more costly). But you can get some idea by checking the Nutrition Facts labels on products you buy and keeping a running tally.

Some bakery goods and breakfast cereals have far more sodium than you'd expect. There's often a wide range of sodium among brands of the same product. Be sure to check the serving size indicated on the label. A bag of chips that looks individual may be listed as multiple servings.

When you cook at home, experts counsel to use only half the salt the recipe calls for; experiment with herbs and spices, or go with the natural flavor. Kids who grow up with less salt may never develop a 'salt tooth.'

It may take a while to get accustomed to less salt, but once your tastes adjust, you may not want to go back. Commissioner Frieden likens reducing salt to switching from whole milk to skim milk. 'If you go back, whole milk tastes like heavy cream,' he says.

早在几十年前，卫生官员就开始敦促美国人少吃点盐。

你知道自己每天的食盐消耗量吗？

普通美国人每天的食盐消耗量约为3,400毫克，远远高于美国膳食指南(U.S. Dietary Guidelines)建议的2,300毫克，同时也是人体所需水平的15倍。

自从二十世纪七十年代以来，食盐的平均消耗量已经上升了大约50%，主要原因是我们食用的便利食品大大增加。食品加工商在减少脂肪和糖份的同时，他们通常会增加食盐的剂量。

不过，食盐过量可能不利于人体健康。

过多摄取盐份可能会引起骨质疏松症、肾脏衰竭和胃癌。更为糟糕的是，它会引起高血压，这是心脏病和中风的主要诱因。每年死于这两种疾病的美国人高达85万之多。

纽约市卫生专员托马斯?弗里登(Thomas Frieden)表示，高血压是仅次于吸烟之后的可预防疾病和死亡的主要原因。弗里登敦促全美包装食品制造商和餐厅在未来10年内逐渐将食盐用量减少50%。美国疾病控制和预防中心(The Centers for Disease Control and Prevention，简称CDC)估计，采取这项措施，不仅每年可以挽救15万人的生命，而且可以减少100亿美元的医疗支出。

大约5000万美国人都患有高血压（即血压水平长时间至少为140/90 mm/Hg）。另有2000万人接近高血压（即血压水平为120/80至139/ 89）。相比白种人，高血压在非裔美国人当中更加普遍，而随着年龄的增大，将近90%的美国人最终都会患上高血压。

有鉴于此，CDC正在敦促所有高血压患者（即非裔美国人或者年龄在40岁以上的美国人，也就是美国将近70%的人口）严格遵从每天食盐摄取量不高于1500毫克的指引。

美国人大约80%食盐摄取量来自加工食品和外出用餐；只有20%来自家庭烹饪或者配餐调料。不过，减少加工食品的盐份并不是件容易的事情。除了能够增强口感之外，食盐还有助于改善食品的质感，并且具有防腐的供销。而长期以来，美国人已经对这种口味习以为常了。

食品制造商协会(Grocery Manufacturers Association)表示，近年来，该协会的许多会员已经开始逐渐减少食品含盐量，并陆续推出低盐食品。但是，它同时表示，任何政府措施都需要增强对消费者的教育以及以科学研究为佐证。

少数批评人士认为，目前并没有足够证据显示大幅降低食盐用量是必要之举。位于纽约州布朗克斯的阿尔波特爱因斯坦医学院(Albert Einstein College of Medicine)的药品和公共卫生教授麦克尔?阿尔德曼(Michael Alderman)表示，并没有充分的科学研究显示普遍降低食盐摄取量可以拯救生命，这样做可能反而会带来意想不到的后果。阿尔德曼博士表示，在某些情况下，降低食盐摄取量可能引发肾脏问题，或者促进胰岛素抗体的生成。阿尔德曼博士目前还担任行业团体盐学会(Salt Institute)的志愿顾问。

CDC心脏病和中风预防中心主任达尔文?拉巴特(Darwin Labarthe)对此持不同意见。他表示，学术界普遍认为降低食盐摄取量有助于减少心脏病和中风的风险，少有证据显示它会引起任何不良的副作用。美国心脏协会(American Heart Association)、美国医学会(American Medical Association)以及世界卫生组织(World Health Organization)都在提倡降低食盐摄取量。

那么，大家应该怎样控制食盐摄取量呢？要想知道确切的食盐摄取量几乎是不可能的事情。即便是食品店的生鸡肉有时候也会被注入盐水以便顾客掂量起来会感觉更沉一些（也就表示更贵一些）。但是，你总是可以从所购买的食品的营养成份标识上略知一二，并进行累计计算。

一些烘培食品和早餐麦片的食盐含量比你预想的要多。同种食品，不同品牌，其食盐含量也会大相径庭。查看食品标签上的一次性食用量会有所帮助。一袋貌似一人份的薯片可能会包括好几次的食用量。

专家建议，如果你在家烹饪的话，那么添加菜谱所建议的食盐用量的一半就可以了；不妨多使用香草和其他调味品，或者选择原味烹饪。摄取盐份较少的孩子可能永远也不会患上“盐牙”。

减少食盐摄取量可能需要一段时间才能适应，但是一旦你的口味调整过来，你可能就不会再想回到过去。纽约市健康专员弗里登把降低食盐摄取量比作从全脂牛奶转向脱脂牛奶。他说，“习惯喝脱脂牛奶后，如果再喝全脂牛奶的话，你会感觉在喝奶油。”