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.   

早在幾十年前，衛(wèi)生官員就開始敦促美國(guó)人少吃點(diǎn)鹽。

你知道自己每天的食鹽消耗量嗎？

普通美國(guó)人每天的食鹽消耗量約為3,400毫克，遠(yuǎn)遠(yuǎn)高于美國(guó)膳食指南(U.S. Dietary Guidelines)建議的2,300毫克，同時(shí)也是人體所需水平的15倍。

自從二十世紀(jì)七十年代以來，食鹽的平均消耗量已經(jīng)上升了大約50%，主要原因是我們食用的便利食品大大增加。食品加工商在減少脂肪和糖份的同時(shí)，他們通常會(huì)增加食鹽的劑量。

不過，食鹽過量可能不利于人體健康。

過多攝取鹽份可能會(huì)引起骨質(zhì)疏松癥、腎臟衰竭和胃癌。更為糟糕的是，它會(huì)引起高血壓，這是心臟病和中風(fēng)的主要誘因。每年死于這兩種疾病的美國(guó)人高達(dá)85萬之多。

紐約市衛(wèi)生專員托馬斯•弗里登(Thomas Frieden)表示，高血壓是僅次于吸煙之后的可預(yù)防疾病和死亡的主要原因。弗里登敦促全美包裝食品制造商和餐廳在未來10年內(nèi)逐漸將食鹽用量減少50%。美國(guó)疾病控制和預(yù)防中心(The Centers for Disease Control and Prevention，簡(jiǎn)稱CDC)估計(jì)，采取這項(xiàng)措施，不僅每年可以挽救15萬人的生命，而且可以減少100億美元的醫(yī)療支出。

大約5000萬美國(guó)人都患有高血壓（即血壓水平長(zhǎng)時(shí)間至少為140/90 mm/Hg）。另有2000萬人接近高血壓（即血壓水平為120/80至139/ 89）。相比白種人，高血壓在非裔美國(guó)人當(dāng)中更加普遍，而隨著年齡的增大，將近90%的美國(guó)人最終都會(huì)患上高血壓。

有鑒于此，CDC正在敦促所有高血壓患者（即非裔美國(guó)人或者年齡在40歲以上的美國(guó)人，也就是美國(guó)將近70%的人口）嚴(yán)格遵從每天食鹽攝取量不高于1500毫克的指引。

美國(guó)人大約80%食鹽攝取量來自加工食品和外出用餐；只有20%來自家庭烹飪或者配餐調(diào)料。不過，減少加工食品的鹽份并不是件容易的事情。除了能夠增強(qiáng)口感之外，食鹽還有助于改善食品的質(zhì)感，并且具有防腐的供銷。而長(zhǎng)期以來，美國(guó)人已經(jīng)對(duì)這種口味習(xí)以為常了。

食品制造商協(xié)會(huì)(Grocery Manufacturers Association)表示，近年來，該協(xié)會(huì)的許多會(huì)員已經(jīng)開始逐漸減少食品含鹽量，并陸續(xù)推出低鹽食品。但是，它同時(shí)表示，任何政府措施都需要增強(qiáng)對(duì)消費(fèi)者的教育以及以科學(xué)研究為佐證。

少數(shù)批評(píng)人士認(rèn)為，目前并沒有足夠證據(jù)顯示大幅降低食鹽用量是必要之舉。位于紐約州布朗克斯的阿爾波特愛因斯坦醫(yī)學(xué)院(Albert Einstein College of Medicine)的藥品和公共衛(wèi)生教授麥克爾•阿爾德曼(Michael Alderman)表示，并沒有充分的科學(xué)研究顯示普遍降低食鹽攝取量可以拯救生命，這樣做可能反而會(huì)帶來意想不到的后果。阿爾德曼博士表示，在某些情況下，降低食鹽攝取量可能引發(fā)腎臟問題，或者促進(jìn)胰島素抗體的生成。阿爾德曼博士目前還擔(dān)任行業(yè)團(tuán)體鹽學(xué)會(huì)(Salt Institute)的志愿顧問。

CDC心臟病和中風(fēng)預(yù)防中心主任達(dá)爾文•拉巴特(Darwin Labarthe)對(duì)此持不同意見。他表示，學(xué)術(shù)界普遍認(rèn)為降低食鹽攝取量有助于減少心臟病和中風(fēng)的風(fēng)險(xiǎn)，少有證據(jù)顯示它會(huì)引起任何不良的副作用。美國(guó)心臟協(xié)會(huì)(American Heart Association)、美國(guó)醫(yī)學(xué)會(huì)(American Medical Association)以及世界衛(wèi)生組織(World Health Organization)都在提倡降低食鹽攝取量。

那么，大家應(yīng)該怎樣控制食鹽攝取量呢？要想知道確切的食鹽攝取量幾乎是不可能的事情。即便是食品店的生雞肉有時(shí)候也會(huì)被注入鹽水以便顧客掂量起來會(huì)感覺更沉一些（也就表示更貴一些）。但是，你總是可以從所購買的食品的營(yíng)養(yǎng)成份標(biāo)識(shí)上略知一二，并進(jìn)行累計(jì)計(jì)算。

一些烘培食品和早餐麥片的食鹽含量比你預(yù)想的要多。同種食品，不同品牌，其食鹽含量也會(huì)大相徑庭。查看食品標(biāo)簽上的一次性食用量會(huì)有所幫助。一袋貌似一人份的薯片可能會(huì)包括好幾次的食用量。

專家建議，如果你在家烹飪的話，那么添加菜譜所建議的食鹽用量的一半就可以了；不妨多使用香草和其他調(diào)味品，或者選擇原味烹飪。攝取鹽份較少的孩子可能永遠(yuǎn)也不會(huì)患上“鹽牙”。

減少食鹽攝取量可能需要一段時(shí)間才能適應(yīng)，但是一旦你的口味調(diào)整過來，你可能就不會(huì)再想回到過去。紐約市健康專員弗里登把降低食鹽攝取量比作從全脂牛奶轉(zhuǎn)向脫脂牛奶。他說，“習(xí)慣喝脫脂牛奶后，如果再喝全脂牛奶的話，你會(huì)感覺在喝奶油。”