鈉攝入量最多的群體，主要是在中國

如果你到了一定的歲數(shù)，你的醫(yī)生或者傳統(tǒng)觀點可能會促使你放下手中的鹽瓶并且慢慢后退。不過，2018年8月11日發(fā)表在《柳葉刀》雜志上的一篇新研究論文正在挑戰(zhàn)這個廣泛給出的建議，這要歸功于一個大規(guī)模的國際研究的結果。

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.

這項研究在平均8年的時間中跟蹤調(diào)查了18個國家超過94000名參與者。所有參與者的年齡都在35歲至70歲，使得他們成為心血管疾病和中風的可能患病人群，而這些疾病長期以來都被認作是過量攝入鈉之后的最為普遍的風險。他們發(fā)現(xiàn)只有那些每天攝入5克鈉以上的人才會增加患上這些病癥的風險。此外，在發(fā)達國家中只有5%的人實際上達到了這個鹽攝入量。

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.

來自麥克馬斯特大學人口健康研究所和加拿大漢密爾頓健康科學的研究者們連同其他幾個國家的同事共同完成了這項研究。科學家們調(diào)查的國家有阿根廷、巴西、加拿大、中國、印度、伊朗、菲律賓、波蘭、沙特阿拉伯、南非、瑞典和坦桑尼亞。大多數(shù)國家每天鈉的攝入量最多是3-5克。研究沒有跟蹤美國的參與者，但是根據(jù)美國疾病防控中心的估計，正常美國人每天會攝入3.4克鈉。

"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.

“世界衛(wèi)生組織建議每天不要攝入超過2克的鈉——那就是1茶匙的鹽——來作為心血管疾病的預防措施，但是基本沒有證據(jù)可以表明如此低攝入量的個體就能改善健康結果，”該研究論文的共同作者Andrew Mente在新聞通稿中解釋說。

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.

美國心臟協(xié)會(AHA)建議那些有心臟病和/或高血壓風險的人群每日鈉攝入量甚至不要超過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.

據(jù)克利夫蘭診所說，雖然沒人清楚到底是什么引發(fā)的高血壓，但是理論是當你吃了太多的鈉，你的身體會鎖住額外的水分想要“沖刷”身體中的鈉。這些額外的水分會通過增加心臟必須泵出到身體中的液體量而增加了心臟的負擔，這會導致你的血壓升高。但是這并不是首個質疑在低鈉攝入量和降低心臟病風險之間是否真的有關聯(lián)的研究論文。

"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."

“只有在那些鈉攝入量最多的群體里——超過每天5克的鈉——主要是在中國，我們才發(fā)現(xiàn)了鈉攝入量和像是心臟病和中風這些主要心血管疾病之間的直接聯(lián)系，”Mente解釋說，“在那些每天鈉攝入量不足5克的群體中，情況正好相反。鈉攝入量和心肌梗塞或心臟病和總死亡數(shù)呈負相關，也不會增加中風的風險。”