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，衛生官員就開始敦促美國人少吃點鹽。

你知道自己每天的食鹽消耗量嗎？

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

自從二十世紀七十年代以來，食鹽的平均消耗量已經上升了大約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，他們通常會增加食鹽的劑量。

不過，食鹽過量可能不利于人體健康。

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

紐約市衛生專員托馬斯•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年內逐漸將食鹽用量減少50%。美國疾病控制和預防中心(The Centers for Disease Control and Prevention，簡稱CDC)估計，采取這項措施，不僅每年可以挽救15萬人的生命，而且可以減少100億美元的醫療支出。

大約5000萬美國人都患有高血壓（即血壓水平長時間至少為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，高血壓在非裔美國人當中更加普遍，而隨著年齡的增大，將近90%的美國人最終都會患上高血壓。

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

美國人大約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。除了能夠增強口感之外，食鹽還有助于改善食品的質感，并且具有防腐的供銷。而長期以來，美國人已經對這種口味習以為常了。

食品制造商協會(Grocery Manufacturers Association)表示，近年來，該協會的許多會員已經開始逐漸減少食品含鹽量，并陸續推出低鹽食品。但是，它同時表示，任何政府措施都需要增強對消費者的教育以及以科學研究為佐證。

少數批評人士認為，目前并沒有足夠證據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學院(Albert Einstein College of Medicine)的藥品和公共衛生教授麥克爾•阿爾德曼(Michael Alderman)表示，并沒有充分的科學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腎臟問題，或者促進胰島素抗體的生成。阿爾德曼博士目前還擔任行業團體鹽學會(Salt Institute)的志愿顧問。

CDC心臟病和中風預防中心主任達爾文•拉巴特(Darwin Labarthe)對此持不同意見。他表示，學術界普遍認為降低食鹽攝取量有助于減少心臟病和中風的風險，少有證據顯示它會引起任何不良的副作用。美國心臟協會(American Heart Association)、美國醫學會(American Medical Association)以及世界衛生組織(World Health Organization)都在提倡降低食鹽攝取量。

那么，大家應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候也會被注入鹽水以便顧客掂量起來會感覺更沉一些（也就表示更貴一些）。但是，你總是可以從所購買的食品的營養成份標識上略知一二，并進行累計計算。

一些烘培食品和早餐麥片的食鹽含量比你預想的要多。同種食品，不同品牌，其食鹽含量也會大相徑庭。查看食品標簽上的一次性食用量會有所幫助。一袋貌似一人份的薯片可能會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味品，或者選擇原味烹飪。攝取鹽份較少的孩子可能永遠也不會患上“鹽牙”。

減少食鹽攝取量可能需要一段時間才能適應，但是一旦你的口味調整過來，你可能就不會再想回到過去。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向脫脂牛奶。他說，“習慣喝脫脂牛奶后，如果再喝全脂牛奶的話，你會感覺在喝奶油。”