Journal Article•
Effect of sodium chloride- and sodium bicarbonate-rich mineral water on blood pressure and metabolic parameters in elderly normotensive individuals: a randomized double-blind crossover trial.
TL;DR: Consumption of sodium chloride-rich mineral water can abolish the blood pressure reduction induced by dietary salt restriction in elderly individuals and may have a beneficial effect on calcium homeostasis.
Abstract: Objective: To examine the effect of sodium chloride- and sodium bicarbonate-rich mineral water on blood pressure and parameters of glucose and lipid metabolism in elderly normotensive individuals.
Methods: We examined 21 healthy men and women aged 60-72 years in a randomized, placebo-controlled, double-blind crossover trial. After reducing dietary salt intake to below 100 mmol/day, study participants were randomly assigned to drink 1.5 l daily of a sodium chloride-rich (sodium 84.5 mmol/l, chloride 63.7 mmol/l, bicarbonate 21.9 mmol/l), a sodium bicarbonate-rich (sodium 39.3 mmol/l, chloride 6.5 mmol/l, bicarbonate 48.8 mmol/l) and a low-sodium (placebo: sodium, chloride and bicarbonate < 0.02 mmol/l) mineral water for 4 weeks each in a three-phase crossover order. Each phase was separated by a 2-week washout period in which the study participants remained on a low-salt diet. Compliance was assessed by biweekly urinary electrolyte excretion and five study participants were excluded from analysis for failing to complete the trial or to fulfil the compliance criteria.
Results: Mean arterial blood pressure was significantly lower during the periods of consuming low-sodium -7.0 +/- 7.2 mmHg, P < 0.001) or sodium bicarbonate-rich (-5.7 +/- 6.4 mmHg, P < 0.05) water than at baseline. In contrast, blood pressure during the phase of drinking sodium chloride-rich water was identical to that at baseline. Ambulatory 24 h blood pressure, oral glucose tolerance and plasma lipids were not affected by the different regimens. Urinary calcium excretion was significantly reduced by drinking low-sodium or sodium bicarbonate-rich water but was unchanged under the sodium chloride-rich water.
Conclusion: Consumption of sodium chloride-rich mineral water can abolish the blood pressure reduction induced by dietary salt restriction in elderly individuals. Sodium bicarbonate-rich mineral water in conjunction with a low-salt diet may have a beneficial effect on calcium homeostasis.
Citations
More filters
TL;DR: A modest reduction in salt intake for four or more weeks causes significant and, from a population viewpoint, important falls in blood pressure in both hypertensive and normotensive individuals.
Abstract: Objective To determine the effects of longer term modest salt reduction on blood pressure, hormones, and lipids. Design Systematic review and meta-analysis. Data sources Medline, Embase, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles. Inclusion criteria Randomised trials with a modest reduction in salt intake and duration of at least four weeks. Data extraction and analysis Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses, and meta-regression were performed. Results Thirty four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt v usual salt) was −75 mmol/24 h (equivalent to a reduction of 4.4 g/day salt), and with this reduction in salt intake, the mean change in blood pressure was −4.18 mm Hg (95% confidence interval −5.18 to −3.18, I 2 =75%) for systolic blood pressure and −2.06 mm Hg (−2.67 to −1.45, I 2 =68%) for diastolic blood pressure. Meta-regression showed that age, ethnic group, blood pressure status (hypertensive or normotensive), and the change in 24 hour urinary sodium were all significantly associated with the fall in systolic blood pressure, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic blood pressure of 5.8 mm Hg (2.5 to 9.2, P=0.001) after adjustment for age, ethnic group, and blood pressure status. For diastolic blood pressure, age, ethnic group, blood pressure status, and the change in 24 hour urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that in people with hypertension the mean effect was −5.39 mm Hg (−6.62 to −4.15, I 2 =61%) for systolic blood pressure and −2.82 mm Hg (−3.54 to −2.11, I 2 =52%) for diastolic blood pressure. In normotensive people, the figures were −2.42 mm Hg (−3.56 to −1.29, I 2 =66%) and −1.00 mm Hg (−1.85 to −0.15, I 2 =66%), respectively. Further subgroup analysis showed that the decrease in systolic blood pressure was significant in both white and black people and in men and women. Meta-analysis of data on hormones and lipids showed that the mean change was 0.26 ng/mL/h (0.17 to 0.36, I 2 =70%) for plasma renin activity, 73.20 pmol/L (44.92 to 101.48, I 2 =62%) for aldosterone, 187 pmol/L (39 to 336, I 2 =5%) for noradrenaline (norepinephrine), 37 pmol/L (−1 to 74, I 2 =12%) for adrenaline (epinephrine), 0.05 mmol/L (−0.02 to 0.11, I 2 =0%) for total cholesterol, 0.05 mmol/L (−0.01 to 0.12, I 2 =0%) for low density lipoprotein cholesterol, −0.02 mmol/L (−0.06 to 0.01, I 2 =16%) for high density lipoprotein cholesterol, and 0.04 mmol/L (−0.02 to 0.09, I 2 =0%) for triglycerides. Conclusions A modest reduction in salt intake for four or more weeks causes significant and, from a population viewpoint, important falls in blood pressure in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. Salt reduction is associated with a small physiological increase in plasma renin activity, aldosterone, and noradrenaline and no significant change in lipid concentrations. These results support a reduction in population salt intake, which will lower population blood pressure and thereby reduce cardiovascular disease. The observed significant association between the reduction in 24 hour urinary sodium and the fall in systolic blood pressure, indicates that larger reductions in salt intake will lead to larger falls in systolic blood pressure. The current recommendations to reduce salt intake from 9-12 to 5-6 g/day will have a major effect on blood pressure, but a further reduction to 3 g/day will have a greater effect and should become the long term target for population salt intake.
1,051 citations
TL;DR: A meta-analysis of randomised salt reduction trials found 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.
Abstract: 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 approximately 10 to approximately 5 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=734) and 11 trials in normotensives (n=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+/-0.40/0.24 mmHg in hypertensives (P<0.001 for both systolic and diastolic) and 2.03/0.97+/-0.27/0.21 mmHg in normotensives (P<0.001 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 (P<0.001 for both systolic and diastolic) in hypertensives and 3.57/1.66 mmHg in normotensive individuals (systolic: P<0.001; diastolic: P<0.05). 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 approximately 14% and coronary deaths by approximately 9% in hypertensives, and reduce stroke and coronary deaths by approximately 6 and approximately 4%, in normotensives, respectively.
766 citations
TL;DR: Assessing the effect of a longer-term modest reduction in salt intake on BP and whether there was a dose-response relationship found that age, ethnic group, BP status and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies.
Abstract: Background
A reduction in salt intake lowers blood pressure (BP) and, thereby, reduces cardiovascular risk. A recent meta-analysis by Graudal implied that salt reduction had adverse effects on hormones and lipids which might mitigate any benefit that occurs with BP reduction. However, Graudal's meta-analysis included a large number of very short-term trials with a large change in salt intake, and such studies are irrelevant to the public health recommendations for a longer-term modest reduction in salt intake. We have updated our Cochrane meta-analysis.
Objectives
To assess (1) the effect of a longer-term modest reduction in salt intake (i.e. of public health relevance) on BP and whether there was a dose-response relationship; (2) the effect on BP by sex and ethnic group; (3) the effect on plasma renin activity, aldosterone, noradrenaline, adrenaline, cholesterol, low-density lipoprotein (LDL), high-density lipoprotein (HDL) and triglycerides.
Search methods
We searched MEDLINE, EMBASE, Cochrane Hypertension Group Specialised Register, Cochrane Central Register of Controlled Trials, and reference list of relevant articles.
Selection criteria
We included randomised trials with a modest reduction in salt intake and duration of at least 4 weeks.
Data collection and analysis
Data were extracted independently by two reviewers. Random effects meta-analyses, subgroup analyses and meta-regression were performed.
Main results
Thirty-four trials (3230 participants) were included. Meta-analysis showed that the mean change in urinary sodium (reduced salt vs usual salt) was -75 mmol/24-h (equivalent to a reduction of 4.4 g/d salt), the mean change in BP was -4.18 mmHg (95% CI: -5.18 to -3.18, I 2=75%) for systolic and -2.06 mmHg (95% CI: -2.67 to -1.45, I 2=68%) for diastolic BP. Meta-regression showed that age, ethnic group, BP status (hypertensive or normotensive) and the change in 24-h urinary sodium were all significantly associated with the fall in systolic BP, explaining 68% of the variance between studies. A 100 mmol reduction in 24 hour urinary sodium (6 g/day salt) was associated with a fall in systolic BP of 5.8 mmHg (95%CI: 2.5 to 9.2, P=0.001) after adjusting for age, ethnic group and BP status. For diastolic BP, age, ethnic group, BP status and the change in 24-h urinary sodium explained 41% of the variance between studies. Meta-analysis by subgroup showed that, in hypertensives, the mean effect was -5.39 mmHg (95% CI: -6.62 to -4.15, I 2=61%) for systolic and -2.82 mmHg (95% CI: -3.54 to -2.11, I 2=52%) for diastolic BP. In normotensives, the mean effect was -2.42 mmHg (95% CI: -3.56 to -1.29, I 2=66%) for systolic and -1.00 mmHg (95% CI: -1.85 to -0.15, I 2=66%) for diastolic BP. Further subgroup analysis showed that the decrease in systolic BP was significant in both whites and blacks, men and women. Meta-analysis of hormone and lipid data showed that the mean effect was 0.26 ng/ml/hr (95% CI: 0.17 to 0.36, I 2=70%) for plasma renin activity, 73.20 pmol/l (95% CI: 44.92 to 101.48, I 2=62%) for aldosterone, 31.67 pg/ml (95% CI: 6.57 to 56.77, I 2=5%) for noradrenaline, 6.70 pg/ml (95% CI: -0.25 to 13.64, I 2=12%) for adrenaline, 0.05 mmol/l (95% CI: -0.02 to 0.11, I 2=0%) for cholesterol, 0.05 mmol/l (95% CI: -0.01 to 0.12, I 2=0%) for LDL, -0.02 mmol/l (95% CI: -0.06 to 0.01, I 2=16%) for HDL, and 0.04 mmol/l (95% CI: -0.02 to 0.09, I 2=0%) for triglycerides.
Authors' conclusions
A modest reduction in salt intake for 4 or more weeks causes significant and, from a population viewpoint, important falls in BP in both hypertensive and normotensive individuals, irrespective of sex and ethnic group. With salt reduction, there is a small physiological increase in plasma renin activity, aldosterone and noradrenaline. There is no significant change in lipid levels. These results provide further strong support for a reduction in population salt intake. This will likely lower population BP and, thereby, reduce cardiovascular disease. Additionally, our analysis demonstrates a significant association between the reduction in 24-h urinary sodium and the fall in systolic BP, indicating the greater the reduction in salt intake, the greater the fall in systolic BP. The current recommendations to reduce salt intake from 9-12 to 5-6 g/d will have a major effect on BP, but are not ideal. A further reduction to 3 g/d will have a greater effect and should become the long term target for population salt intake.
594 citations
TL;DR: The effects of low sodium intake versus high sodium intake on systolic and diastolic blood pressure, plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high- density lipoprotein (HDL), low-density lipop Protein (LDL) and triglycerides are estimated.
Abstract: Background
In spite of more than 100 years of investigations the question of whether a reduced sodium intake improves health is still unsolved.
Objectives
To estimate the effects of low sodium intake versus high sodium intake on systolic and diastolic blood pressure (SBP and DBP), plasma or serum levels of renin, aldosterone, catecholamines, cholesterol, high-density lipoprotein (HDL), low-density lipoprotein (LDL) and triglycerides.
Search methods
The Cochrane Hypertension Information Specialist searched the following databases for randomized controlled trials up to March 2016: the Cochrane Hypertension Specialised Register, the Cochrane Central Register of Controlled Trials (CENTRAL) (2016, Issue 3), MEDLINE (from 1946), Embase (from 1974), the World Health Organization International Clinical Trials Registry Platform, and ClinicalTrials.gov. We also searched the reference lists of relevant articles.
Selection criteria
Studies randomising persons to low-sodium and high-sodium diets were included if they evaluated at least one of the above outcome parameters.
Data collection and analysis
Two review authors independently collected data, which were analysed with Review Manager 5.3.
Main results
A total of 185 studies were included. The average sodium intake was reduced from 201 mmol/day (corresponding to high usual level) to 66 mmol/day (corresponding to the recommended level).
The effect of sodium reduction on blood pressure (BP) was as follows: white people with normotension: SBP: mean difference (MD) -1.09 mmHg (95% confidence interval (CI): -1.63 to -0.56; P = 0.0001); 89 studies, 8569 participants; DBP: + 0.03 mmHg (MD 95% CI: -0.37 to 0.43; P = 0.89); 90 studies, 8833 participants. High-quality evidence.
Black people with normotension: SBP: MD -4.02 mmHg (95% CI:-7.37 to -0.68; P = 0.002); seven studies, 506 participants; DBP: MD -2.01 mmHg (95% CI:-4.37 to 0.35; P = 0.09); seven studies, 506 participants. Moderate-quality evidence.
Asian people with normotension: SBP: MD -0.72 mmHg (95% CI: -3.86 to 2.41; P = 0.65); DBP: MD -1.63 mmHg (95% CI:-3.35 to 0.08; P =0.06); three studies, 393 participants. Moderate-quality evidence.
White people with hypertension: SBP: MD -5.51 mmHg (95% CI: -6.45 to -4.57; P < 0.00001); 84 studies, 5925 participants; DBP: MD -2.88 mmHg (95% CI: -3.44 to -2.32; P < 0.00001); 85 studies, 6001 participants. High-quality evidence.
Black people with hypertension: SBP MD -6.64 mmHg (95% CI:-9.00 to -4.27; P = 0.00001); eight studies, 619 participants; DBP -2.91 mmHg (95% CI:-4.52, -1.30; P = 0.0004); eight studies, 619 participants. Moderate-quality evidence.
Asian people with hypertension: SBP: MD -7.75 mmHg (95% CI:-11,44 to -4.07; P < 0.0001) nine studies, 501 participants; DBP: MD -2.68 mmHg (95% CI: -4.21 to -1.15; P = 0.0006). Moderate-quality evidence.
In plasma or serum, there was a significant increase in renin (P < 0.00001), aldosterone (P < 0.00001), noradrenaline (P < 0.00001), adrenaline (P < 0.03), cholesterol (P < 0.0005) and triglyceride (P < 0.0006) with low sodium intake as compared with high sodium intake. All effects were stable in 125 study populations with a sodium intake below 250 mmol/day and a sodium reduction intervention of at least one week.
Authors' conclusions
Sodium reduction from an average high usual sodium intake level (201 mmol/day) to an average level of 66 mmol/day, which is below the recommended upper level of 100 mmol/day (5.8 g salt), resulted in a decrease in SBP/DBP of 1/0 mmHg in white participants with normotension and a decrease in SBP/DBP of 5.5/2.9 mmHg in white participants with hypertension. A few studies showed that these effects in black and Asian populations were greater. The effects on hormones and lipids were similar in people with normotension and hypertension. Renin increased 1.60 ng/mL/hour (55%); aldosterone increased 97.81 pg/mL (127%); adrenalin increased 7.55 pg/mL (14%); noradrenalin increased 63.56 pg/mL: (27%); cholesterol increased 5.59 mg/dL (2.9%); triglyceride increased 7.04 mg/dL (6.3%).
508 citations
TL;DR: The results do not support a general recommendation to reduce sodium intake, but reduced sodium intake may be used as a supplementary treatment in hypertension.
Abstract: Context.—One of the controversies in preventive medicine is whether a general
reduction in sodium intake can decrease the blood pressure of a population
and thereby reduce the number of strokes and myocardial infarctions. In recent
years the debate has been extended by studies indicating that reduced sodium
intake has adverse effects.Objective.—To estimate the effects of reduced sodium intake on systolic and diastolic
blood pressure (SBP and DBP), body weight, and plasma or serum levels of renin,
aldosterone, catecholamines, cholesterols, and triglyceride, and to evaluate
the stability of the blood pressure effect in relation to additional trials.Data Sources.—MEDLINE search from 1966 through December 1997 and reference lists of
relevant articles.Study Selection.—Studies randomizing persons to high-sodium and low-sodium diets were
included if they evaluated at least one of the effect parameters.Data Extraction.—Two authors independently recorded data.Data Synthesis.—In 58 trials of hypertensive persons, the effect of reduced sodium intake
as measured by urinary sodium excretion (mean, 118 mmol/24 h) on SBP was 3.9
mm Hg (95% confidence interval [CI], 3.0-4.8 mm Hg) (P<.001)
and on DBP was 1.9 mm Hg (95% CI, 1.3-2.5 mm Hg) (P<.001).
In 56 trials of normotensive persons, the effect of reduced sodium intake
(mean, 160 mmol/24 h) on SBP was 1.2 mm Hg (95% CI, 0.6-1.8 mm Hg) (P<.001) and on DBP was 0.26 mm Hg (95% CI, −0.3-0.9
mm Hg) (P=.12). The cumulative analysis showed that
this effect size has been stable since 1985. In plasma, the renin level increased
3.6-fold (P<.001), and the aldosterone level increased
3.2-fold (P<.001); the increases were proportional
to the degree of sodium reduction for both renin (r=0.66; P<.001) and aldosterone (r=0.64; P<.001). Body weight decreased significantly, and noradrenaline,
cholesterol, and low-density lipoprotein cholesterol levels increased. There
was no effect on adrenaline, triglyceride, and high-density lipoprotein cholesterol.Conclusion.—These results do not support a general recommendation to reduce sodium
intake. Reduced sodium intake may be used as a supplementary treatment in
hypertension. Further long-term studies of the effects of high reduction of
sodium intake on blood pressure and metabolic variables may clarify the disagreements
as to the role of reduced sodium intake, but ideally trials with hard end
points such as morbidity and survival should end the controversy.
499 citations