No abstract

The effect of small doses of four commercially available aluminum-containing antacids on calcium and phosphorus metabolism was investigated in adult males in 20 studies. During the use of these doses of antacids, urinary and fecal calcium increased significantly during a low calcium intake averaging 252 mg/day, and the calcium balances became distinctly more negative. There was a reversal of the normal pattern of phosphorus excretions, namely, the fecal phosphorus was high and the urinary phosphorus was low. During a normal calcium intake of 800 mg/day, these doses of antacids did not result in significant changes of the calcium excretions or balance. Despite the decrease in net intestinal absorption of calcium, the average 47Ca absorption remained unchanged, irrespective of the type and dose of antacid used. In three patients who received large therapeutic doses of antacids, 240 to 450 ml/day, the changes of calcium and phosphorus metabolism were intensified.

The increased Mg intake of 826 mg did not affect intestinal Ca absorption determined with tracer doses of 47Ca during Ca intakes of 241 and 812 mg/day.

The effect of a high protein (meat) intake of 2 g/kg on the calcium excretions and retention and on the intestinal calcium absorption was studied in man. In the control study the protein intake averaged 1 g/kg. The studies were carried out during a low calcium intake of 200 mg/day and a normal calcium intake of 800 mg/day. Two additional studies were carried out during a calcium intake of 1100 mg/day and one during a 2000 mg calcium intake. During the high protein-low calcium intake and during the 800 mg calcium intake the urinary calcium did not significantly increase. It increased moderately in two studies during the higher calcium intakes, however, these excretions decreased with time to control levels. The lack of a significant increase of the urinary calcium in the majority of the studies is probably due to the higher phosphorus content of the high protein intake. The calcium absorption, determined with 47Ca, the fecal calcium and calcium balances did not differ significantly during the high protein intake. In studies carried out during a low protein (meat) intake of 0.5 g/kg the urinary calcium changed little and the fecal calcium, the 47Ca absorption, and the calcium balance remained unchanged.

Previous studies in this Unit have shown that a high protein intake, given as meat, did not induce hypercalciuria, except for the initial and temporary increase in two subjects. In the present investigation the long-term effect of a high meat diet on calcium metabolism was studied for 78 to 132 days in four adult males and the short-term effect for 18 to 30 days in three subjects. Calcium and phosphorus balances and calcium absorption studies, using 47Ca as the tracer, were carried out. During the long-term high meat intake and during the short-term high meat studies, there was no significant change of the urinary or fecal calcium nor of the calcium balance. There was also no significant change of the intestinal absorption of calcium during the high meat intake. These long- and short-term studies have confirmed our previous results that a high protein intake, given as meat, does not lead to hypercalciuria and does not induce calcium loss.