Water sodium, urinary electrolytes, and blood pressure of adolescents.

Abstract

SUMMARY Blood pressure measurements were made on children in their fourth year at secondary schools in parts of Scunthorpe Health District supplied with drinking water of varying sodium content. Of the 3131 children, 2740 were examined (1394 boys and 1346 girls). Boys had slightly higher systolic pressures and slightly lower diastolic pressures than the girls. There was no difference between the blood pressure distributions of children in areas supplied with water containing 105 mg/l sodium, 50 mg/l sodium, or less than 15 mg/l sodium. Small differences were found in the weights of children in these areas, and slightly more of the children in the area supplied with water containing more than 105 mg/l sodium had relatives who had been treated for hypertension. Standardisation for these factors did not show any relation between water salinity and either systolic or diastolic blood pressure. Studies of the urinary sodium, potassium, and the ratios of these to creatinine on a sample of 769 boys showed no correlation with assessments of usual sodium intake, but urinary sodium correlated well with salt and fluid intake at the meal immediately preceding examination. The relation between median blood pressure and urinary sodium concentration and lack of a clear relation with sodium creatinine ratio supports the hypothesis that it may be the ratio of salt to fluid intake rather than total dietary sodium that is relevant to the regulation of blood pressure.Attempts by a working group of the World Health Organisation in 1977 to set soundly based international standards for the sodium content of public water supplies were impeded by the dearth of reliable information as to the effects on the health of populations of potable water with differing concentrations of this element.'In many parts of the world boreholes yield waters containing substantial amounts of sodium, and the rise in salinity of some surface water sources as a result of increasing use of salt to clear snow and ice from roads has caused concern. This has stimulated several studies aimed at ascertaining whether or not consumption of such waters constitutes a hazard to health.Studies by Calabrese and Tuthill in the United States23 and by Hofman et all in the Netherlands have reported appreciably higher blood pressures in children living in areas supplied with water containing around 110 mg Na/1 than in children in areas of low water salinity. Although both were based on small numbers of subjects, and the pressures found were within the normal physiological range, these findings suggest the possibility that exposure of large populations to such water might be expected to result in a substantial increase in the incidence of hypertensive disease. These results, however, were surprising in view of the small contribution to the total sodium intake that such water would make to individuals consuming a normal western European or American diet. They conflict with evidence from a study of mortality in populations supplied with similar water which experienced fewer deaths...

Drinking water salinity and risk of hypertension: A systematic review and meta-analysis

“…Some studies in the USA, Netherlands and Israel have found a positive relationship between elevated sodium in drinking water and rise in blood pressure 12,13,14,15 . However other studies in USA and Australia did not observe any such relationship 16,17,18,19 . The recent studies in coastal Bangladesh demonstrated an unacceptably high level of sodium in water contributing to high prevalence of hypertension in pregnant mothers 7,20 .…”

“…We also excluded one study that used hypertension mortality as the only end point 21 and two articles 22,23 that reported on the same study population as other included studies 12,13 . Eight studies were also excluded as they did not report SBP and DBP level 17,18,24,25 or provide information that allowed us to calculate SD 16,26,27 or OR 28 .…”

Diet and blood pressure in children and adolescents

“…Nine of the urinary sodium studies, reported in 7 papers and ranging in sample size from 72 to 322, did not control for other factors [14 -20]. Six of the 9 studies (reported in 5 papers) found no significant associations between urinary sodium and BP [6,14,15,17,18], whereas the other 3 found significant positive associations between urinary sodium and either SBP [16,19] or mean BP [20].…”

Significant sodium plasma reduction after half-ironman triathlon in Brazilian triathletes

“…This internal regulation occurs by the secretion of antidiuretic hormone and thirst stimulation when osmolality rises 5 to 10 mOsmol/ kg H 2 0, thus not leading to a clinical sodium plasma reduction due to fluid overload (Robertson, 1984). Speedy et al (2001) reported that ironman athletes, with fluid intake estimated by recall, showed no significant pre-and post race plasma sodium alterations, with a relative inverse relationship between change in sodium plasma concentration and weight loss, similarly to results obtained from the same author in 1999, were the relative body change of severely hyponatremic athletes was increased during the event, thus associating this condition to a fluid overload.…”