“…17 Among the 28 trials included in our meta-analysis, 14,18-41 10 had to have variance imputed. 18,19,23,24,27,31,32,38,39 Mean effect sizes were calculated by weighting each trial by the inverse of the variance. 16 Weighted linear regression was used to examine the dose response relationship between the change in urinary sodium and the change in blood pressure.…”
Section: Statistical Analysesmentioning
confidence: 99%
“…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.…”
Section: Effect On Blood Pressurementioning
confidence: 99%
“…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. 18 The study Figure 1 Summary of studies assessed and excluded through the stages of the meta-analysis.…”
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.…”
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.
“…17 Among the 28 trials included in our meta-analysis, 14,18-41 10 had to have variance imputed. 18,19,23,24,27,31,32,38,39 Mean effect sizes were calculated by weighting each trial by the inverse of the variance. 16 Weighted linear regression was used to examine the dose response relationship between the change in urinary sodium and the change in blood pressure.…”
Section: Statistical Analysesmentioning
confidence: 99%
“…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.…”
Section: Effect On Blood Pressurementioning
confidence: 99%
“…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. 18 The study Figure 1 Summary of studies assessed and excluded through the stages of the meta-analysis.…”
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.…”
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.
A slight reduction in saturated fat intake, along with the use of extra-virgin olive oil, markedly lowers daily antihypertensive dosage requirement, possibly through enhanced nitric oxide levels stimulated by polyphenols.
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