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Bone. 2003 Oct;33(4):557-66.

Comparative effects of vitamin K and vitamin D supplementation on prevention of osteopenia in calcium-deficient young rats.

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  • 1Department of Sports Medicine, Keio University School of Medicine, Tokyo, Japan. jiwamoto@sc.itc.keio.ac.jp

Erratum in

  • Bone. 2004 Mar;34(3):589-90.

Abstract

The aim of this study was to clarify the difference in the effects of vitamin K and vitamin D supplementation on the development of osteopenia in young rats under mild calcium deficiency. Sixty female Sprague-Dawley rats, 6 weeks of age, were randomized by stratified weight method into six groups with 10 rats in each group: baseline control, 0.5% (normal) calcium diet, 0.1% (low) calcium diet, 0.1% calcium diet + vitamin K (30 mg/100 g, food intake), 0.1% calcium diet + vitamin D (25 microg/100 g, food intake), and 0.1% calcium diet + K + D. After 10 weeks of feeding, serum calcium, 25-hydroxyvitamin D(3) [25 (OH) D(3)], 1,25-dihydroxyvitamin D(3) [1,25 (OH)(2) D(3)], and parathyroid hormone (PTH) levels were measured, and intestinal calcium absorption and renal calcium reabsorption were evaluated. Bone histomorphometric analyses were performed on cortical bone of the tibial shaft and cancellous bone of the proximal tibia. Calcium deficiency induced hypocalcemia, increased serum PTH and 1,25 (OH)(2) D(3) levels with decreased serum 25 (OH) D(3) level, stimulated intestinal calcium absorption and renal calcium reabsorption, and reduced maturation-related cortical bone gain as a result of decreased periosteal bone gain and enlarged marrow cavity but did not significantly influence maturation-related cancellous bone gain. Vitamin K supplementation in calcium-deficient rats stimulated renal calcium reabsorption, retarded the abnormal elevation of serum PTH level, increased maturation-related cancellous bone gain, and retarded the reduction in maturation-related cortical bone gain. On the other hand, vitamin D supplementation in calcium-deficient rats stimulated intestinal calcium absorption via increased serum 1,25 (OH)(2) D(3) level with prevention of the abnormal elevation of serum PTH level, prevented hypocalcemia, reduced the maturation-related cancellous bone gain, and prevented the reduction in periosteal bone gain and enhanced enlargement of the marrow cavity with no significant effect on the reduction in maturation-related cortical bone gain. However, no synergistic effect of vitamin K and vitamin D on intestinal calcium absorption, renal calcium reabsorption, and cancellous and cortical bone mass was found. This study shows the differential effects of vitamin K and vitamin D supplementation on the development of osteopenia in young rats under mild calcium deficiency. Vitamin K supplementation stimulates renal calcium reabsorption, increases maturation-related cancellous bone gain, and retards the reduction in maturation-related cortical bone gain, whereas vitamin D supplementation stimulates intestinal calcium absorption and prevents the reduction in maturation-related periosteal bone gain by inducing accumulation of calcium from cancellous and endocortical bone.

PMID:
14555259
[PubMed - indexed for MEDLINE]
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