证据资料



www WASH
Google

干预研究

对不到500名新生儿进行的一项双盲对照试验显示,限盐组的盐摄入量减少约30%(通过检测尿钠浓度进行判断),收缩压即获得改善。在第六个月末,低盐组婴儿的收缩压降低2.1mmHg(P<0.01)。研究于6个月时结束。

15年后重新对这些婴儿进行研究。对其他因素进行校正后发现,头六个月限盐与不限盐的婴儿相比,两者的血压仍存在明显差别,这说明早期的盐摄入对血压有长期影响,该试验结果与多项动物试验结果相符。

Figure 1. Difference in systolic blood pressure in newborn babies, randomised to either a normal salt intake or a moderate reduction in salt intake over the first six months of life. At six months, the study was discontinued, with all participants resuming a normal salt intake. Fifteen years later, a subgroup of those in the study had blood pressure re-measured. (Adapted from Ref. 1,2).

另一项成功的限盐干预研究是在葡萄牙。研究选择了葡萄牙的两个村庄,向其中一个村庄的居民宣传如何限盐,并向居民提供低含盐量食品,居民盐摄入量减少一半(通过24h内尿钠排泄量判断);而另一村庄的居民并不限盐。一年以后,两村居民的血压出现差别;第二年,与对照组相比,限盐居民的收缩压和舒张压都明显下降。

另外两项干预研究都经常作为负面例子引用。两项试验都未能成功限盐,因此毫不奇怪在这些研究中,与对照组相比,那些想限盐而未能成功限盐的干预组血压未出现变化。上述两项研究取得的唯一结论就是,发达国家80%的盐都隐藏在食品中,因此除非提供低盐食品,否则很难做到限盐。

Figure 2. Blood pressure changes with time in two Portuguese villages, one of which was advised on how to reduce salt intake and given processed foods with a reduced salt content, the other had similar measurements of blood pressure but no advice on diet. Note the significant differences in blood pressure at 1 year and continuing differences at 2 years. (Adapted from Ref. 3).

参考文献

(1) Trials of Hypertension Prevention Collaborative Research Group. The effects of nonpharmacologic interventions on blood pressure of persons with high normal levels. Results of the trials of hypertension prevention, phase I. JAMA 1992;267:1213-20.

(2) Trials of Hypertension Prevention Collaborative Research Group. Effects of weight loss and sodium reduction intervention on blood pressure and hypertension incidence in overweight people with highnormal blood pressure. The trials of hypertension prevention, phase II. The trials of hypertension prevention collaborative research group. Arch Intern Med 1997;157:657-67.

(3) Cook NR, Cutler JA, Obarzanek E, Buring JE, Rexrode KM, Kumanyika SK Appel LJ & Whelton PK. Long term effects of dietary sodium reduction on cardiovascular disease outcomes: observational follow-up of the trials of hypertension prevention (TOTP). BMJ, Apr 2007; 334: 885; doi: 10.1136/bmj.39147.604896.55

(4) Hofman A, Hazebroek A, Valkenburg H A. A randomized trial of sodium intake and blood pressure in newborn infants. Jama. 1983;250:370-3.

(5) Geleijnse J M, Hofman A, Witteman J C, et al. Long-term effects of neonatal sodium restriction on blood pressure. Hypertension. 1997;29:913-7.

(6) Forte J G, Miguel J M, Miguel M J, et al.. Salt and blood ressure: a community trial. J Hum Hypertens. 1989;3:179-84.

(7) Staessen J, Bulpitt C J, Fagard R, et al. Salt intake and blood pressure in the general population: a controlled intervention trial in two towns. J Hypertens. 1988;6:965-73.

(8) Tuomilehto J, Puska P, Nissinen A, et al. Community-based prevention of hypertension in North Karelia, Finland. Ann Clin Res. 1984;16 Suppl 43:18-27.