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.
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.


CONCLUSIONS
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.
Schorr
U
U
Department of Internal Medicine, Universitätsklinikum Benjamin Franklin, Free University of Berlin, Germany.
Distler
A
A
Sharma
A M
AM
D000368:Aged; D000450:Aldosterone / Q000097:blood; D009320:Atrial Natriuretic Factor / Q000097:blood / Q000187:drug effects; D001786:Blood Glucose / Q000187:drug effects; D001794:Blood Pressure / Q000187:drug effects*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D006801:Humans; D007328:Insulin / Q000097:blood; D008055:Lipids / Q000097:blood; D008297:Male; D008875:Middle Aged; D008900:Mineral Waters / Q000032:analysis; D009318:Natriuresis / Q000187:drug effects; D012016:Reference Values; D012083:Renin / Q000097:blood / Q000187:drug effects; D017693:Sodium Bicarbonate / Q000494:pharmacology*; D012965:Sodium Chloride / Q000494:pharmacology*
D001786:Blood Glucose; D007328:Insulin; D008055:Lipids; D008900:Mineral Waters; D012965:Sodium Chloride; D000450:Aldosterone; D009320:Atrial Natriuretic Factor; D017693:Sodium Bicarbonate; D012083:Renin