Sj. Whiting et al., CALCIURIC EFFECTS OF PROTEIN AND POTASSIUM BICARBONATE BUT NOT OF SODIUM-CHLORIDE OR PHOSPHATE CAN BE DETECTED ACUTELY IN ADULT WOMEN AND MEN, The American journal of clinical nutrition, 65(5), 1997, pp. 1465-1472
An acute load test was used to test the influence of dietary factors o
n urinary calcium excretion. In study 1, 10 fasting premenopausal wome
n consumed test meals providing a moderate amount of protein (MP; 23 g
), MP plus 23 mmol KHCO3 (MP + K), MP plus 23 mmol NaCl (MP + Na), and
a high amount of protein (HP; 53 g), HP plus 70 mmol KHCO3 (HP + K),
and HP plus 70 mmol NaCl (HP + Na). Protein was casein:lactalbumin (80
:20), except for the treatments with added sodium chloride, to which o
nly casein was added. In study 2, the effects of HP and HP plus 50 mmo
l KHCO3 (HP + K) were compared with those of MP or MP plus 7.5 mmol ph
osphate (MP + Pi), equaling the additional phosphate of HP, in 10 adul
t men. Subjects completed all treatments in random order. In study 1,
the peak of calcium excretion was at 3 h for all treatments, except fo
r HP + K, which indicated an acute hypocalciuric effect of potassium.
Unexpectedly, there was no hypercalciuric effect of adding sodium chlo
ride, nor was urine sodium increased. In study 2, calcium excretion wa
s significantly higher with HP than with MP + Pi but not with MP at 3
h, indicating an acute hypercalciuric effect of protein alone. A hypoc
alciuric effect of potassium (HP + K compared with HP) but not of phos
phate (MP compared with MP + Pi) was seen. An acute load test measurin
g changes 3 h postload was appropriate for examining the calciuric eff
ects of protein and potassium bicarbonate, but not those of sodium chl
oride or phosphate in adults.