The interrelation of urinary calcium and sodium intake in healthy elderly Japanese

To evaluate whether habitual excess sodium intake is significant as a risk factor for calcium loss in elderly Japanese, a relationship between calcium excretion and sodium excretion was studied in 39 male and 44 female Japanese, aged 60 and over. They are healthy, free-living and consuming a self-selected diet. A significant positive correlation between urinary calcium excretion and sodium excretion per 24-hour was observed both in males (r = .415, p less than 0.01) and in females (r = .330, p less than 0.05). The relationship was still significant even after adjustment for sex, age, body mass index, alkaline phosphatase levels and protein as well as calcium and phosphorus intake. It was estimated that the increase in urinary calcium excretion was about 1.0 mmol/day per 100 mmol increase in urinary sodium excretion.