Over the years, Americans have become inured to salt. Most people have no idea how much salt they consume — onaverage, about 9 to 12 g (or 3,600 to 4,800 mg of sodium) per person per day, according to the American Heart Association (AHA). That's twice the amount recommended by the government.

    In the past four decades, Americans' salt consumption has risen 50%, mostly as a result of eating more processed foods and more food prepared in restaurants. "Over time, we have adapted our taste buds and adapted our bodies to crave much, much higher levels of salt than we require to function," says Dr. Kirsten Bibbins-Domingo, an epidemiologist at the University of California, San Francisco.

    Some salt is crucial for good health, of course — to regulate blood pressure and assist with muscle and nerve function — but too much (that is, at the levels we currently consume) can lead to hypertension, heart disease and stroke. If Americans halved their salt intake, as many as 150,000 premature deaths could be prevented each year, according to the American Medical Association. And new research presented March 11 by Bibbins-Domingo at the AHA's annual conference shows that even small reductions — as little as 1 g of salt per day — could have dramatic effects, saving 200,000 lives over the course of a decade.

    Using a sophisticated computer model to analyze trends in heart disease over time among U.S. adults, Bibbins-Domingo and colleagues discovered that incremental population-wide reductions could drastically improve public health. Cutting out just 1 g of salt (or 40 mg of sodium) per person per day could prevent 30,000 cases of coronary heart disease across the U.S. population by 2019. Reducing consumption by half — a more sizable 6 grams — could prevent 1.4 million cases of heart disease during that same period.

    While eating less salt would improve the health of the population across the board, researchers found that the benefits would be greatest for African Americans and women. As a group, African Americans tend to have higher blood pressure than the general population, and "many studies suggest that they may be more sensitive to salt," Bibbins-Domingo says. Her analysis found that a reduction of 3 g of salt per day would reduce heart attacks 8% on average; among African Americans, that rate would drop 10%. A similar result was found in women, whose stroke risk dropped 8% with a 3-g reduction in salt intake; in men, the risk fell 5%.

    The numbers certainly offer compelling incentives to cut salt consumption, but that's no easy task. You can put down the salt shaker and cut back on obviously salty snacks, but there's still so much sodium packed into processed foods that trying to extract it from your diet is a tricky business. "It's so pervasive in an average U.S. diet that it's really hard to tell people, 'You have to avoid salt,' " says Bibbins-Domingo.

    And there is salt hiding in places you wouldn't think to look. According to a sodium chart from the U.S. Department of Agriculture, a single slice of commercially made whole-wheat bread has 148 mg of sodium; white bread has 170 mg. Cheerios contains 213 mg of sodium per cup; Total Raisin Bran, 239 mg. And then there are the big offenders: processed soups and sauces. Chicken noodle soup, for example, even after it has been diluted with water during preparation, has a whopping 1,106 mg of sodium per cup. "I think people don't have a clue," says Bibbins-Domingo. "The recommended daily amount of salt is about a teaspoon," she says. "It's easy to add that much if you're just adding salt," let alone all of the salt that's in food before we break out the shaker.

    If you're dining out, all bets are off. According to the British organization Consensus Action on Salt in Health, a three-course meal in a restaurant can contain more than 15 g of salt, almost three times the recommended daily amount.

    Bibbins-Domingo says it's especially tough for families with limited income, who tend to rely more on processed or packaged foods and canned fruits and vegetables rather than fresh foods. Patients tell her they've cut salted nuts, potato chips and pretzels from their diet and started eating more soup instead. "You realize that they're actually consuming more salt in their attempt to make healthy choices," she says.

    Any large-scale success in salt-intake reduction would have to involve policymakers and the food industry, say public-health experts. "If you could reduce blood pressure by just a few points, you could reduce hundreds of thousands of deaths," says Dr. Thomas Frieden, commissioner of New York City's Department of Health and Mental Hygiene, who recently announced a national campaign to diminish salt intake 20% in the next five years and 40% in the next decade. Frieden, who has in the past targeted trans fats and led the charge to require chain restaurants to list calorie content on menus, has evoked less animosity from the food and restaurant industries with his desalinization efforts than with his previous initiatives.

    "[Frieden] is looking for voluntary guidelines. It's a national movement, and he's working closely with the industry on developing these re-education guidelines," says Rob Bookman, an attorney for the New York State Restaurant Association, but he adds wryly, "I don't know if it's one big happy family."

    Frieden points to a successful salt-reduction campaign in the U.K. as a kind of proof of principle. Several years after the British government launched an aggressive national campaign, which included voluntary reductions in salt content by food manufacturers, British citizens had reduced their annual sodium consumption roughly 10%. "If you look at what happened in the U.K., at first the industry was very concerned," Frieden says. "But after a few years, they saw that they could drop their salt content 20% to 30% [without losing customers]."

    For Bibbins-Domingo, the issue is less about mandating food production or proscribing salt consumption than enabling people to make better choices. "This is actually something that we can achieve with very little cost to our personal liberties," she says.

    But Frieden adheres to a harder line. When asked whether the government should be allowed to influence how or what we eat, he responded with a pointed rhetorical question: "Should industry be allowed to serve us food that makes us sick and kills us?"

    這些年來，美國人已經習慣了食用（大量的）鹽。大多數人并不知道自己每天攝入了多少鹽——據美國心臟協會統計，平均下來，每人每天大概9-12克（相當于3600-4800毫克的鈉）。這是政府推薦攝入量的兩倍。

    在過去的四十年，美國人鹽的消費量增加了50%，主要是因為人們更多得食用加工食品，更多得在餐館就餐。“一直以來，我們都在縱容自己的口味，縱容自己的身體對鹽的需要，攝入了大量的鹽，遠遠超過滿總生理機能所需的量”舊金山加利福尼亞大學的比賓斯-多明戈博士如是說。

    當然，鹽對我們的健康至關重要——調節血壓，輔助肌肉和神經功能。但是，過量的鹽（比如我們目前的攝入量）會導致高血壓、心臟病和中風。據美國醫學學會稱，如果美國人的鹽攝入量減半，每年將會有150，000人避免過早死亡。比賓斯-多明戈 3月11日在美國心臟學會（AHA）年度研討會上公布的最新研究表明，即便微小的調節，比如每天減少1克，都會帶來顯著的效果——在未來的十年挽救 200，000人的生命。

    比賓斯-多明戈和其同事用高性能計算機模型分析了美國成年人心臟病的發展動態，發現全民減少攝入鹽能夠大幅度提高公共健康水平。如果每人每天減少1克的鹽攝入（或者40毫克的鈉），在2019年前，能夠在全國范圍內預防30，000例冠心病的發作；如果鹽的攝入量減半——大約6克，在同一時期內，能夠預防140萬例心臟病的發作。

    減少食用鹽能夠提高國民的健康水平，研究人員發現這種成效在非裔美國人和婦女身上更為明顯。比起普通居民，非裔美國人的血壓更高，比賓斯-多明戈說：“大量研究表明他們可能對鹽更為敏感。”她的分析顯示，平均來說，每天減少3克的鹽攝入將會降低8%的心臟病發作率；而在非裔美國人中間，這一比例將會是10%。相似的結果出現在女性身上。每減少3克的鹽攝入，發病概率降低 8%；而對男性來說，這一比例為5%。

    這些數字毫無疑問刺激人們去減少鹽的攝入量，但這可不是一個簡單的任務。你可以放下鹽瓶，放棄明顯的咸味點心，但是，在加工過的食品中卻含有大量的納，把他們從你的食譜中剔除會是一件相當棘手的事。比賓斯-多明戈說：“在美國人的日常食物中，它（加工過的食品）是如此的常見，以至于你很難去告訴人們‘你必須遠離鹽’”。

    在一些你永遠都不會注意的地方也存在著鹽。根據美國農業部的一份鈉含量的圖表，一片市面上出售的全麥面包含有148毫克的鈉；白面包有170毫克。每一杯 Cheerios含有213毫克的鈉；Total Raisin Bran,139毫克。鈉含量的大戶還有：精心熬制的湯和醬。比如說，雞肉面條湯，即便在烹制期間加水稀釋，每杯仍含有驚人的1106毫克的鈉。“我想人們毫無頭緒”，比賓斯-多明戈說。她說：“推薦的食用量是一湯匙。如果你只是隨便加入鹽的話，就很容易超量”。一定要把食物里所有的鹽弄出來，直到你的振動篩被用壞。

    如果你在外邊吃飯，那一切都完了。根據英國組織“為了健康　同心抗鹽”的調查，餐館里的三餐含有高達15克的鹽——幾乎三倍于推薦食用量。

    比賓斯-多明戈說，對于收入拮據的家庭，（減少鹽的食用量）尤為困難。因為他們更為依賴經過加工包裝的食品，更多得食用罐裝蔬菜和水果，而不是新鮮的。有病人告訴她，他們已經從食譜中剔除了腌堅果、薯片和椒鹽餅干，而開始食用更多的湯。她說：“你能看到他們本想選擇更加健康的飲食，實際上卻食用了更多的鹽。”

    公共健康專家稱，任何減少鹽的攝入量的大規模行動的成功，都必然牽涉到決策者和食品工業。托馬斯.弗里登博士說：“如果能夠讓血壓降低哪怕很小的幅度，就能夠挽救成百上千的生命。”托馬斯.弗里登博士是紐約市健康及心理衛生署署長，他最近公開發起了一項全民運動，目的是在未來的5年內減少鹽的攝入量20%，十年內減少40%。弗里登，就是那個曾經把目標指向脂肪，領導了要求連鎖餐館在菜單上列出卡利路含量的那場斗爭的人。（他）因除去鹽分的努力而招致的食品和餐飲行業的怨恨，比他先前的活動還要少。

    “弗里登正在尋找自愿準則。這是一場全民運動，他正在和食品行業緊密合作，制定他們的再培訓準則。”紐約餐館聯盟的代理律師Rob Bookman說，但是他略帶諷刺得補充說：“我不知道會不會出現皆大歡喜的局面。”

    弗里登指出，英國發生的一場成功的“減鹽”運動，可以作為重要借鑒。幾年前，英國政府發動了一場轟轟烈烈的全民運動，其中包括食品生產廠家自愿減少鹽的含量。英國居民鹽的攝入量已經減少了大概10%。弗里登說：“如果你觀察一下，你會發現，最初企業都很憂慮，經年之后，他們發現即使鹽的含量減少了20%- 30%,他們卻沒有失去買主。”

    對比賓斯-多明戈來說，行動的目的是讓人們有機會做出更好的選擇，而不是苛責食品行業和管制鹽的消費。她說：“我們確實可以促進我們的個人自由，只需付出很小的代價”

    但是弗里登堅持強硬路線。當被問及政府是否應該被允許去影響我們吃什么、怎么吃時，他尖銳得反問道：“食品行業應該被允許供給會毒害我們的健康甚至殺死我們的食物嗎？”