【柳叶刀】全球性研究:低盐饮食不利健康,颠覆传统认知
2016/05/24
人们通常认为,高盐饮食容易导致一些健康问题的发生,低盐饮食、水果、运动、低脂肪饮食等有利于身体健康。然而,5月20日,《柳叶刀》上的一项全球性研究表明低盐饮食对心脏健康不利,颠覆了传统认知。


人们通常认为,高盐饮食容易导致一些健康问题的发生,低盐饮食、水果、运动、低脂肪饮食等有利于身体健康。然而,5月20日,《柳叶刀》上的一项全球性研究表明低盐饮食对心脏健康不利,颠覆了传统认知。

该研究由加拿大麦克马斯特大学临床流行病学和生物统计学副教授Andrew Mente引领,综合了四项关于钠摄入量和心脏健康的研究,共涉及了49个国家133000名志愿者,这些研究均对志愿者的晨尿样本进行评估,将尿液中钠含量低于3000毫克归为低钠组,高于7000毫克的归为高钠组。

结果发现,对于无高血压人群,低盐饮食会增加26%的心脏病或中风风险;对于高血压人群,低盐饮食增加34%的心脏病或中风风险,而高盐饮食增加23%的心脏病或中风风险。此外,该研究发现对于血压正常的人群,过量摄入食盐不会增加高血压的风险。

Mente博士表示,将钠摄入量限制在3000毫克/天以内似乎增加心脏病风险,这与高盐饮食增加高血压风险相类似,因而既不太低也不太高的钠摄入量最佳。此外,低盐饮食可以激活体内的肾素-血管紧张素系统,该系统是血压和体液平衡的激素调节系统,如果试图通过降低钠来降低血压,那么在血压下降的同时也激活了体内的肾素-血管紧张素系统。

最后研究人员指出,只有高血压患者需要注意减少钠的摄入量。

低盐饮食不利健康,引争议

然而,美国心脏协会却认为该研究对钠摄入量的评估存在缺陷。美国心脏协会前任会长、哈佛医学院临床转化研究院副院长Elliott Antman博士认为,“该分析存在严重的缺陷,因此不应该用来指导公共政策。美国心脏协会将继续建议钠的摄入量在1500毫克/天以内。”然而据统计,大多数美国人钠的摄入量为3400毫克/天,超过推荐量的两倍。

Antman补充到,研究人员假定测量尿钠可以准确告知某个时间段的钠摄入量,他担心这样的新闻报道会误导人们的饮食选择,除非研究人员指出这种分析的不足之处,否则可能带来一些重大的公共卫生问题。

纽约勒诺克斯山医院的注册营养师Sharon Zarabi称,盐作为人类饮食的一部分已有几千年,但加工业的出现,导致其被大量使用于调味或作为防腐剂。“我们利用DASH饮食方法来治疗高血压,这种饮食包括各种水果和蔬菜,并限制盐的加入量。正如多数膳食研究所述,所有食物的摄入量都应当适度,应尽量避免调味品和加工食品,如沙拉酱、芥末、乳酪、酱汁和面包产品等。”

纽约史泰登岛大学医院心脏科主任Howard Levite博士认为大多数人钠摄入量适中的观点是有争议的,柳叶刀上的研究结论并不反驳控制盐量可预防心脏病的观点,此外该研究还提出了一种可能性,即人达到中年后,现行的钠摄入量指南可能需要做相应的改变,但这也不能否定已有的指南的预防意义。

备注:本文根据外文网站编译,原文链接如下Could a Low-Salt Diet Hurt Your Health?

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  • Associations of urinary sodium excretion with cardiovascular events in individuals with and without hypertension: a pooled analysis of data from four studies

    Background Several studies reported a U-shaped association between urinary sodium excretion and cardiovascular disease events and mortality. Whether these associations vary between those individuals with and without hypertension is uncertain. We aimed to explore whether the association between sodium intake and cardiovascular disease events and all-cause mortality is modified by hypertension status. Methods In this pooled analysis, we studied 133 118 individuals (63 559 with hypertension and 69 559 without hypertension), median age of 55 years (IQR 45–63), from 49 countries in four large prospective studies and estimated 24-h urinary sodium excretion (as group-level measure of intake). We related this to the composite outcome of death and major cardiovascular disease events over a median of 4·2 years (IQR 3·0–5·0) and blood pressure. Findings Increased sodium intake was associated with greater increases in systolic blood pressure in individuals with hypertension (2·08 mm Hg change per g sodium increase) compared with individuals without hypertension (1·22 mm Hg change per g; pinteraction<0·0001). In those individuals with hypertension (6835 events), sodium excretion of 7 g/day or more (7060 [11%] of population with hypertension: hazard ratio [HR] 1·23 [95% CI 1·11–1·37]; p<0·0001) and less than 3 g/day (7006 [11%] of population with hypertension: 1·34 [1·23–1·47]; p<0·0001) were both associated with increased risk compared with sodium excretion of 4–5 g/day (reference 25% of the population with hypertension). In those individuals without hypertension (3021 events), compared with 4–5 g/day (18 508 [27%] of the population without hypertension), higher sodium excretion was not associated with risk of the primary composite outcome (≥7 g/day in 6271 [9%] of the population without hypertension; HR 0·90 [95% CI 0·76–1·08]; p=0·2547), whereas an excretion of less than 3 g/day was associated with a significantly increased risk (7547 [11%] of the population without hypertension; HR 1·26 [95% CI 1·10–1·45]; p=0·0009). Interpretation Compared with moderate sodium intake, high sodium intake is associated with an increased risk of cardiovascular events and death in hypertensive populations (no association in normotensive population), while the association of low sodium intake with increased risk of cardiovascular events and death is observed in those with or without hypertension. These data suggest that lowering sodium intake is best targeted at populations with hypertension who consume high sodium diets.

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