SHORT-TERM CHANGES IN CALCIUM BUT NOT PROTEIN-INTAKE ALTER THE RATE OF BONE-RESORPTION IN HEALTHY-SUBJECTS AS ASSESSED BY URINARY PYRIDINIUM CROSS-LINK EXCRETION
Sa. Shapses et al., SHORT-TERM CHANGES IN CALCIUM BUT NOT PROTEIN-INTAKE ALTER THE RATE OF BONE-RESORPTION IN HEALTHY-SUBJECTS AS ASSESSED BY URINARY PYRIDINIUM CROSS-LINK EXCRETION, The Journal of nutrition, 125(11), 1995, pp. 2814-2821
This study was conducted to determine whether the markers of bone reso
rption, pyridinium cross-links of collagen, are sensitive to changes i
n dietary protein and calcium intake. Fifteen young healthy subjects (
7 males and 8 females) participated in three 5-d diet periods. Dietary
intake during each dietary period consisted of: I) low nitrogen and l
ow calcium [0.49 +/- 0.11 g protein/ (kg . d), 429 +/- 190 mg calcium/
d]; 2) low nitrogen and high calcium [0.44 +/- 0.08 g protein/(kg . d)
, 1643 +/- 171 mg calcium/d]; and 3) a high nitrogen and high calcium
[2.71 +/- 0.75 g protein/(kg . d), 1589 +/- 633 mg calcium/dl diet, an
d this was compared with subjects' baseline dietary intake [0.99 +/- 0
.51 g protein/(kg . d), 589 +/- 152 mg calcium/d]. The order of these
diets was randomly assigned. Twenty-four-hour and 3-h urine samples we
re collected before and during each dietary period and were analyzed f
or pyridinium cross-links (pyridinoline, deoxypyridinoline), nitrogen
and creatinine. The rate of pyridinium crosslink excretion did not var
y with protein intake but was similar to 33% lower (P < 0.01) during p
eriods of high compared with low calcium intake. These data indicate t
hat a short-term increase in calcium intake is accompanied by a reduce
d rate of bone resorption and that this effect is independent of dieta
ry protein intake.