人們通常認為，過度減少鹽的攝入對身體健康沒有益處，甚至?xí)黾右恍┘膊〉陌l(fā)病率，縮短壽命。但一項發(fā)表在《心血管病進展》上的最新研究反駁了此看法。

赫爾辛基大學(xué) Heikki Karppanen 博士和 Kuopio 大學(xué) Eero Mervaala 博士表示，在過去 30 年里芬蘭人的鹽攝入量平均降低了 30％-35％，與之相應(yīng)，65 歲以下人群中風(fēng)和冠心病的死亡率也大幅度下降了 75％-80％。在此期間，芬蘭人的預(yù)期壽命延長了 6-7 年。

出現(xiàn)這種令人歡欣的改變最主要是由于人們的平均血壓下降了 10 mmHg，，平均膽固醇水平也有明顯下降，從而降低了心臟病的發(fā)病率，但藥物在這方面僅起到 10% 的作用。

美國食鹽協(xié)會的銷售數(shù)據(jù)顯示，在 80 年代中期到 90 年代末的 15 年間，美國的鹽攝入量增加了五成之多。該研究指出，高血壓的患病率曾一度出現(xiàn)下降趨勢，但隨著鹽攝入量的增加而再次上升。

研究中最有趣的是發(fā)現(xiàn)了鹽攝入與肥胖之間的緊密關(guān)系。研究指出，增多鈉鹽攝入勢必會引起口渴，伴隨而來的是飲料的攝入量增加，從而使美國在該時期的卡路里攝入量出現(xiàn)明顯的凈增加。在美國 1977-2001 年間，從加糖飲料中獲得的能量平均增加了 135%，與此同時，從牛奶中獲得的能量卻減少了 38%。這樣每人每天的能量攝入量凈增加了 278 千焦。美國心臟協(xié)會估計，為了消耗這每天增加的 278 千焦卡路里，避免肥胖癥或使肥胖加劇，每個美國人每天應(yīng)比 1977 年多步行或吸塵 1 小時 10 分鐘。不幸的是，人們并沒有這樣做。與 1976-1980 年相比， 1988-1994 年間患肥胖癥的男性增加了 61%，女性則增加了 52%，而 1999-2002 年間患肥胖癥的男性增加了 120%，女性則增加了 99%。鹽的攝入增多，也會增加口渴，從而增加了高能量飲料的攝入，這顯然促使了美國肥胖癥患病率升高。

值得注意的是，1983 年前美國的鹽攝入量沒有變化，甚至出現(xiàn)持續(xù)的下降趨勢。此段時期肥胖癥的患病率也相應(yīng)較低，而且在 60 年代早期到 80 年代早期沒有太大的變化。研究顯示，在現(xiàn)在的工業(yè)化社會，肥胖問題一直是懸而未決的難題，全面減少鹽的攝入可以減少高能量飲料的攝入，這是減少肥胖癥的一種強而有效的方法。

研究員認為，現(xiàn)在有確證證明全面減少鹽的攝入對身體健康有益，而且還能減少肥胖。在芬蘭的長期人口調(diào)查結(jié)果顯示，大量減少鹽的攝入并沒有副作用。Karppanen 教授認為，各企業(yè)反復(fù)發(fā)出全面減少鹽攝入有損身體健康的警告，這種做法是不正當(dāng)?shù)?，而且是不道德的?

http://www.eurekalert.org/pub_releases/2006-11/uoh-sii110106.php

Salt intake is strongly associated with obesity
Comprehensive reduction in salt intake would be a powerful means against obesity, claims new study
A study published in the journal "Progress in Cardiovascular Diseases" refutes the frequently repeated claims that a comprehensive salt reduction would not produce any overall health benefits, or would even increase diseases and shorten the life-span.

Professors, Dr. Heikki Karppanen of the University of Helsinki and Dr. Eero Mervaala of the University of Kuopio report that an average 30-35 % reduction in salt intake during 30 years in Finland was associated with a dramatic 75 % to 80 % decrease in both stroke and coronary heart disease mortality in the population under 65 years. During the same period the life expectancy of both male and female Finns increased by 6 to 7 years.

The most powerful explaining factor for the favorable changes was the more than 10 mmHg ("point") decrease in the average blood pressure of the population. A marked decrease in the average cholesterol levels of the population also remarkably contributed to the decrease of heart diseases. The extensive use of drugs contributed less than 10 % of the observed decreases in blood pressure, cholesterol, and cardiovascular diseases.

"To our surprise, the sales figures of the American Salt Institute divulged that salt intake increased more than 50 % in USA during 15 years from mid-1980s to the late 1990s", says Professor Karppanen. The study reports that the prevalence of high blood pressure, which had long shown a decreasing trend, turned to a marked increase concomitantly with the increase in salt intake.

Perhaps the most interesting finding of the study is the close link between salt intake and obesity. The study reports that increasing intakes of sodium (salt) obligatorily produce a progressive increase in thirst. The progressive increase in the average intake of salt explains the observed concomitant increase in the intake of beverages which, in turn, has caused a marked net increase in the intake of calories during the same period in the United States.

Between 1977 and 2001, energy intake from sweetened beverages increased on the average by 135 % in the United States. During the same period, the energy intake from milk was reduced by 38 %. The net effect on energy intake was a 278 kcal increase per person a day. The American Heart Association has estimated that, to burn the average increase of 278 kcal a day and avoid the development or worsening of obesity, each American should now walk or vacuum 1 hour 10 minutes more every day than in 1977. Unfortunately, this has not been the case.

In a decade from 1976-1980 to 1988-1994 the prevalence of obesity increased 61 % among men and 52 % among women. During 1999 to 2002, the prevalence of obesity was 120 % higher among men and 99 % higher among women as compared with the 1976 to 1980 figures. The increased intake of salt, through induction of thirst with increased intake of high-energy beverages has obviously remarkably contributed to the increase of obesity in the United States.

It is noteworthy that, until 1983 the use of salt did not change or even showed a continuous decreasing trend in the United States. The prevalence of obesity was relatively low and remained essentially unchanged from early 1960s to early 1980s. The study suggests that a comprehensive reduction in salt intake, which would reduce the intake of high-energy beverages, would be a potentially powerful means in the so far failed attempts to combat obesity in industrialized societies.

The authors conclude that there now is conclusive population-wide evidence, which indicates powerful beneficial health effects of comprehensive salt reduction. Decrease of obesity is now added to the previous list of recognized benefits. The population-wide long-term experience from Finland indicates that a remarkable decrease in the salt intake has not caused any adverse effects. Professor Karppanen states that "the repeated warnings of various industries on possible harmful effects of comprehensive salt reduction are unjustified and even unethical".

編輯：藍色幻想

編輯： 張靖

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