Affiliations: Department of Nutritional Science, Faculty of Applied
Bioscience, Tokyo University of Agriculture, 1-1-1 Sakuragaoka, Setagaya-ku,
Tokyo 156-8502, Japan. Tel.: +81 3 5477 2444; E-mail: Kazu@nodai.ac.jp
Note: [] Corresponding author
Abstract: We investigated the effect of dietary calcium:phosphorus (Ca:P)
ratio on bone mineralization and intestinal Ca absorption in ovariectomized
(OVX) rat models of osteoporosis and sham-operated rats. Thirty 12-wk-old
female Wistar rats were divided into three groups of OVX rats and three groups
of sham rats. Thirty days after the adaptation period, OVX rats and sham rats
were fed a diet formulated Ca:P, 1:0.5, 1:1 or 1:2 (each diet containing 0.5%
Ca), respectively for 42 d. In both sham and OVX rats, serum osteocalcin, a
marker of bone turnover, was increased by decreasing Ca:P ratio (1:2). In
contrast, rats fed the Ca:P = 1:0.5 diet (dietary P
restriction) suppressed the increased serum parathyroid hormone, osteocalcin
and urinary deoxypyridinoline, and increased Ca absorption in both sham and OVX
rats compared to the Ca:P = 1:1 and 1:2 diets. Especially,
in OVX rats, the decreased bone mineral density of the fifth lumbar was also
suppressed when rats were fed the Ca:P = 1:0.5 diet. These
results indicated that the elevation of dietary Ca:P ratio may inhibit bone
loss and increase intestinal Ca absorption in OVX rats.
