钠摄入量最多的群体，主要是在中国

如果你到了一定的岁数，你的医生或者传统观点可能会促使你放下手中的盐瓶并且慢慢后退。不过，2018年8月11日发表在《柳叶刀》杂志上的一篇新研究论文正在挑战这个广泛给出的建议，这要归功于一个大规模的国际研究的结果。

The study followed more than 94,000 people in 18 countries for an average of eight years. All participants were aged 35 to 70, making them likely candidates for potential cardiovascular disease and stroke, long considered to be the most prevalent risks of excessive sodium. They found that only people who consume greater than 5 grams of sodium per day (which is about 2.5 teaspoons of salt) are at increased risk of related problems. What's more, a mere 5 percent of people in developed countries actually meet that staggering salt intake.

这项研究在平均8年的时间中跟踪调查了18个国家超过94000名参与者。所有参与者的年龄都在35岁至70岁，使得他们成为心血管疾病和中风的可能患病人群，而这些疾病长期以来都被认作是过量摄入钠之后的最为普遍的风险。他们发现只有那些每天摄入5克钠以上的人才会增加患上这些病症的风险。此外，在发达国家中只有5%的人实际上达到了这个盐摄入量。

Researchers from the Population Health Research Institute (PHRI) of McMaster University and Hamilton Health Sciences in Canada, completed the study in tandem with colleagues from several countries. The countries the scientists examined included Argentina, Brazil, Canada, China, India, Iran, the Philippines, Poland, Saudi Arabia, South Africa, Sweden and Tanzania. Most countries topped out at 3 to 5 grams of sodium per day. Participants in the United States were not followed, but the Centers for Disease Control and Prevention estimates that the average American takes in 3,400 milligrams (3.4 grams) of sodium per day.

来自麦克马斯特大学人口健康研究所和加拿大汉密尔顿健康科学的研究者们连同其他几个国家的同事共同完成了这项研究。科学家们调查的国家有阿根廷、巴西、加拿大、中国、印度、伊朗、菲律宾、波兰、沙特阿拉伯、南非、瑞典和坦桑尼亚。大多数国家每天钠的摄入量最多是3-5克。研究没有跟踪美国的参与者，但是根据美国疾病防控中心的估计，正常美国人每天会摄入3.4克钠。

"The World Health Organization recommends consumption of less than two grams of sodium -- that's one teaspoon of salt -- a day as a preventative measure against cardiovascular disease, but there is little evidence in terms of improved health outcomes that individuals ever achieve at such a low level," explained study co-author Andrew Mente in a press release.

“世界卫生组织建议每天不要摄入超过2克的钠——那就是1茶匙的盐——来作为心血管疾病的预防措施，但是基本没有证据可以表明如此低摄入量的个体就能改善健康结果，”该研究论文的共同作者Andrew Mente在新闻通稿中解释说。

The American Heart Association (AHA) suggests an even lower limit of 1,500 milligrams (1.5 grams) of sodium per day for people at risk of heart disease and/or with high blood pressure.

美国心脏协会(AHA)建议那些有心脏病和/或高血压风险的人群每日钠摄入量甚至不要超过1.5克。

Although no one knows what exactly causes high blood pressure, the theory is that when you eat too much sodium, your body has to hold extra water in order to "wash" salt from your body, according to the Cleveland Clinic. This extra water puts stress on your heart by increasing the amount of fluid it must pump through the body, which may cause your blood pressure to rise. But this is not the first study to question whether there is really a link between lowering sodium intake and reducing heart attack risk.

据克利夫兰诊所说，虽然没人清楚到底是什么引发的高血压，但是理论是当你吃了太多的钠，你的身体会锁住额外的水分想要“冲刷”身体中的钠。这些额外的水分会通过增加心脏必须泵出到身体中的液体量而增加了心脏的负担，这会导致你的血压升高。但是这并不是首个质疑在低钠摄入量和降低心脏病风险之间是否真的有关联的研究论文。

"Only in the communities with the most sodium intake — those over five grams a day of sodium — which is mainly in China, did we find a direct link between sodium intake and major cardiovascular events like heart attack and stroke," explained Mente. "In communities that consumed less than five grams of sodium a day, the opposite was the case. Sodium consumption was inversely associated with myocardial infarction or heart attacks and total mortality, and no increase in stroke."

“只有在那些钠摄入量最多的群体里——超过每天5克的钠——主要是在中国，我们才发现了钠摄入量和像是心脏病和中风这些主要心血管疾病之间的直接联系，”Mente解释说，“在那些每天钠摄入量不足5克的群体中，情况正好相反。钠摄入量和心肌梗塞或心脏病和总死亡数呈负相关，也不会增加中风的风险。”