URINARY EXCRETION OF CALCIUM, MAGNESIUM, SODIUM, AND POTASSIUM IN HARD AND SOFT WATER AREAS

Abstract

There is evidence that the death-rate from cardiovascular disease is higher where the drinking-water is soft than in areas where it is hard. The urinary excretions of calcium, magnesium, sodium, and potassium of men living in hard and soft water areas were compared. Urinary excretion was used as an approximate estimate of the amounts of these elements absorbed. Single specimens of urine were obtained from 157 men living in London (hard water) and 196 men in the soft-water areas of Glasgow, Bradford, Plymouth, and Preston. The specimens were analysed for creatinine, calcium, magnesium, sodium, and potassium, and the amounts of the four elements excreted were calculated assuming that the mean creatinine excretion of men was 25 mg. per kg. per 24 hours. The contribution made by hard or soft water itself, or vegetables cooked in it, to the intakes of the four elements was also determined. The amounts of calcium, magnesium, and potassium excreted in the hard and soft water areas were not significantly different. The excretion of sodium was significantly higher in the soft-water areas than in London. This was almost certainly due to salt added to the food.