Double-blind randomised trial of modest salt restriction in older people

Cappuccio, Francesco P.; Markandu, Nirmala D.; Carney, Christine; Sagnella, Giuseppe A.; MacGregor, Graham A.

doi:10.1016/s0140-6736(97)02264-2

Cited by 167 publications

(103 citation statements)

References 13 publications

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“…42,43 Results Figure 1 shows the number of studies assessed and excluded through the stages of the meta-analysis. A total of 28 trials with 2954 subjects 14, were found that fitted the inclusion criteria: 17 trials were in hypertensive 14,18-33 and 11 in normotensives 14,23,[33][34][35][36][37][38][39][40][41] (in three trials 14,23,33 where both hypertensives and normotensives were studied, the data on hypertensives and normotensives were recorded separately). In two trials 14,28 where three levels of salt intakes were studied, we included the high and intermediate levels (ie urinary sodium reduced from 190 to 108 mmol/day) in one trial, 28 and in the other (DASH-Sodium study) 14 we included the high and low levels (ie urinary sodium reduced from 145 to 65 mmol/day in hypertensives and from 139 to 64 mmol/day in normotensives on the normal American diet).…”

Section: Statistical Analysesmentioning

confidence: 99%

“…14,[18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33] The median age was 50 years (ranging from 24 to 73 years). Of the 17 trials, 11 employed crossover design 14,18,20,21,24,[27][28][29][31][32][33] and six used paralleled comparisons. 19,22,23,25,26,30 Nine out of the 17 trials were double-blind, 20,21,27-33 seven were blood pressure observer-blind, 14,19,[22][23][24][25][26] and one did not report any blinding procedure.…”

Section: Effect On Blood Pressurementioning

confidence: 99%

“…Trials in normotensive individuals: A total of 2220 normotensive individuals were studied in 11 trials. 14,23,[33][34][35][36][37][38][39][40][41] The median age was 47 years (ranging from 22 to 67 years). Of the 11 trials, six employed cross-over design.…”

Section: Effect On Blood Pressurementioning

confidence: 99%

“…14,[33][34][35]38,40 and five used paralleled comparisons. 23,36,37,39,41 Seven of the 11 trials were double-blind [33][34][35][36][38][39][40] and four were blood pressure observer-blind. 14,23,37,41 The study duration varied from 4 weeks to 3 years (median: 4 weeks).…”

Section: Effect On Blood Pressurementioning

confidence: 99%

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Effect of modest salt reduction on blood pressure: a meta-analysis of randomized trials. Implications for public health

2002

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Two recent meta-analyses of randomised salt reduction trials have concluded that there is little purpose in reducing salt intake in the general population. However, the authors, as with other previous meta-analyses, included trials of very short duration (eg 1 week or less) and trials of acute salt loading followed by abrupt reductions to very low salt intake (eg from 20 to less than 1 g of salt/day). These acute salt loading and salt depletion experiments are known to increase sympathetic tone, and with salt depletion cause a rise in renin release and, thereby, plasma angiotensin II. These trials are not appropriate, therefore, for helping to inform public health policy, which is for a more modest reduction in salt intake, ie, from a usual intake of E10 to E5 g of salt per day over a more prolonged period of time. We carried out a meta-analysis to assess the effect of a modest salt reduction on blood pressure. Our data sources were MEDLINE, EMBASE, Cochrane library, CINAHL, and the reference lists of original and review articles. We included randomised trials with a modest reduction in salt intake and a duration of 4 or more weeks. Meta-analysis, meta-regression, and funnel plots were performed. A total of 17 trials in hypertensives (n ¼ 734) and 11 trials in normotensives (n ¼ 2220) were included in our study. The median reduction in 24-h urinary sodium excretion was 78 mmol (equivalent to 4.6 g of salt/day) in hypertensives and 74 mmol in normotensives. The pooled estimates of blood pressure fall were 4.96/2.73 7 0.40/0.24 mmHg in hypertensives (Po0.001 for both systolic and diastolic) and 2.03/ 0.97 7 0.27/0.21 mmHg in normotensives (Po0.001 for both systolic and diastolic). Weighted linear regression analyses showed a dose response between the change in urinary sodium and blood pressure. A reduction of 100 mmol/day (6 g of salt) in salt intake predicted a fall in blood pressure of 7.11/3.88 mmHg (Po0.001 for both systolic and diastolic) in hypertensives and 3.57/ 1.66 mmHg in normotensive individuals (systolic: Po0.001; diastolic: Po0.05). Our results demonstrate that a modest reduction in salt intake for a duration of 4 or more weeks does have a significant and, from a population viewpoint, important effect on blood pressure in both hypertensive and normotensive individuals. This meta-analysis strongly supports other evidence for a modest and long-term reduction in population salt intake, and would be predicted to reduce stroke deaths immediately by E14% and coronary deaths by E9% in hypertensives, and reduce stroke and coronary deaths by E6 and E4%, in normotensives, respectively.

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Section: Statistical Analysesmentioning

confidence: 99%

Section: Effect On Blood Pressurementioning

confidence: 99%

Section: Effect On Blood Pressurementioning

confidence: 99%

Section: Effect On Blood Pressurementioning

confidence: 99%

See 2 more Smart Citations

Effect of modest salt reduction on blood pressure: a meta-analysis of randomized trials. Implications for public health

2002

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“…Randomized trials have demonstrated that even modest sodium restriction reduces BP in both normotensive and hypertensive individuals, [3][4][5][6] although the reported effects are often variable and modest in magnitude. The debate continues over the extent to which this variable response is conditioned by race and age, or other risk attributes, such as obesity and diets low in fruits and vegetables.…”

Section: Introductionmentioning

confidence: 99%

A randomized trial on sodium reduction in two developing countries

et al. 2004

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Hypertension remains the most common cardiovascular risk factor in developing countries, yet the majority of patients have no access to pharmacological therapy. Population-wide preventive strategies, such as salt restriction, are an attractive alternative, but experience in resource-poor settings is limited. To address this question, we conducted a randomized crossover study of salt restriction in adults living in Nigeria and Jamaica in order to estimate the mean blood pressure (BP) response. After a 4-week run-in period to determine willingness to adhere to a low-salt diet, 56 Jamaicans and 58 Nigerians completed an 8-week crossover study of low-salt and high-salt intake. Baseline BPs were in the normotensive range (systolic ¼ 125 mmHg in Jamaica, 114 mmHg in Nigeria). Baseline urinary sodium excretion was 86.8 and 125.6 mEq/day in Nigeria and Jamaica, respectively. The mean difference between urinary sodium excretion at baseline and at the end of the 3-week low-sodium phase was 33.6 mEq/day in Nigeria and 57.5 mEq/day in Jamaica. During the high-sodium phase, mean change in urinary sodium excretion from baseline to week 3 was 35.0 and 5.5 mEq/day in Nigeria and Jamaica, respectively. The mean change in systolic BP ('high' vs 'low' sodium phase) was approximately 5 mmHg in both groups. This study suggests that the efficacy of sodium reduction in developing countries equals those noted in more affluent cultures. If promoted on a wide scale, sodium reduction could be used to treat persons with established hypertension, and more importantly, to prevent age-related increases in BP in poor communities.

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