人体摄入太多的钠（盐的主要成份）会增加罹患高血压的机率。对大多数人来说，高血压是步入老年期的一个主要风险，因为它会导致心脏疾病和其它健康问题。然而，减少膳食中的钠摄入量并非易事，主要是因为人们往往没有意识到自己吃的食物里含有纳。人们摄入的钠有四分之三以上来自加工食品和餐馆食物，而我们吃的东西里头有很多钠尝起来并没有咸味，比如袋装面包和鸡肉菜肴等。
控制盐分摄入是美国人健康饮食之战的一个最新战场，之前的努力主要集中在降低糖分摄入、控制糖尿病、减少脂肪摄入量和防范心脏疾病等方面。四十多年来，美国政府一直试图减少美国人膳食结构中的盐分摄入量，但事与愿违，人们吃盐反而吃得更多。因此，政府目前正在加大这方面的努力。
美国新的膳食指南预计在2010年下半年出台，参与指南制定的一个顾问委员会最近建议，所有的美国成年人应将每日钠摄入量控制在1,500毫克以内，差不多相当于三分之二茶匙的食盐。对一些人而言，现行的摄入上限是2,300毫克。但对许多人来说，摄入上限并没有发生什么变化。美国的膳食指南每五年更新一次，现行标准为高血压患者、40岁以上者和非洲裔美国人每日摄入量不超过1,500毫克，因为后两类人群患高血压的机率高于一般人。上述群体占了美国成年人总数的70%。
美国疾病控制与预防中心(Centers for Disease Control and Prevention)最近的一项调查发现，目前美国成年人平均每天摄入3,400毫克的钠，是推荐标准的两倍以上，而这还不包括他们做饭时放的盐以及吃饭时从盐瓶里 到食物上的盐。现在的中年男性每天吃下去的食盐平均要比20世纪70年代的中年男性高出54%左右，而中年女性更是高出了67%。
减少盐分摄入量的最佳方式是少吃加工食品和餐馆食物，多吃新鲜食材，以及减少每餐的量。营养学家建议人们多吃全麦谷物，少吃面包，因为单单一片袋装面包就含有至少150 毫克到200毫克的钠。减少盐分摄入量应该是一个渐进的过程，这样你的味蕾就能逐步适应较淡的口味。
哈佛公共卫生学院(Harvard School of Public Health)建议，购买加工食品时，尽量保证每包食品的钠含量应少于300毫克，或每卡路里的食物内钠含量不超过1毫克。该学院在网站上介绍了由美国厨艺学院(Culinary Institute of America)研究出来的25种减少钠摄入量的方法。
近年来，许多消费者都已经在注意减少脂肪摄入量，但可能并没有注意到，那些他们以为比较健康的食品里头含有大量的钠。
人体需要一定量的钠以支持身体的正常运转，比如保持体液的平衡等。过量的钠通常会由肾脏来进行处理，但如果肾脏不能完全处理掉多余的钠，在体内累积的纳可能会导致血流量的增加，动脉血压因而上升。如果患上高血压，就可能引发心脏疾病、肾脏疾病等各种健康问题。
Betsy McKay
Eating too much sodium, a key component of salt, can contribute to high blood pressure, a major risk for most people as they age because it can lead to heart disease and other health problems. But cutting sodium from the diet is difficult, mainly because people often don't know it's there. More than three-quarters of the sodium people consume comes from processed and restaurant foods. And much of the sodium we eat is in foods that don't necessarily taste salty, like packaged bread and chicken dishes.
Salt is the latest front in the battle to get Americans to eat a healthier diet. Previous efforts have focused on cutting down on sugar, to fight obesity, and reducing fat, for a healthier heart. After four decades of unsuccessfully nudging Americans to cut salt in their diets only to see them eat more of it, government officials are intensifying their efforts.
An advisory committee working on new U.S. Dietary Guidelines, due to be released later this year by the federal government, recently recommended that all adults restrict their intake of sodium to no more than 1,500 milligrams a day, equivalent to about two-thirds of a teaspoon of table salt, down from a current limit of 2,300 mgs for some people. For many, that wouldn't represent a change. The dietary guidelines, which are updated every five years, currently suggest a limit of 1,500 mgs for people with hypertension, anyone over 40 years old and African-Americans, who are at greater risk for high blood pressure -- a group that represents about 70% of all adults.
Today, adults consume more than 3,400 mgs of sodium on average, not including salt they use in cooking or sprinkle on food from a shaker, more than twice the amount recommended for most people, according to a recent survey by the Centers for Disease Control and Prevention. Middle-aged men are eating on average about 54% more salt today than in the early 1970s; for women, consumption has jumped 67% in that time.
The best way to reduce salt is to cut back on processed and restaurant foods, eat fresh produce, and reduce portion sizes. Nutritionists recommend eating whole grains instead of bread -- a single slice of packaged bread can contain 150 mgs to 200 mgs or more of sodium. Cut back gradually, so your palate adjusts to a less salty taste.
When you do buy processed foods, look for items with less than 300 mg of sodium per serving, or no more than one milligram of sodium per calorie of food, advises the Harvard School of Public Health, which has on its website 25 sodium-reduction strategies developed with the Culinary Institute of America.
Many consumers have focused in recent years on cutting back on fat and may not have noticed that foods they think are healthier may have lots of sodium.
Bodies need some sodium to function properly, including maintaining the right balance of fluids, and excess sodium is usually kept in check by the kidneys. But if the kidneys can't eliminate enough sodium, the buildup of sodium can lead to an increase in blood volume, which in turn increases pressure in the arteries. High blood pressure, or hypertension, can lead to heart disease, stroke, kidney disease and other problems.
Betsy McKay
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