Vitamin D supplementation suppresses age-induced bone turnover in older women who are vitamin D deficient.

J Steroid Biochem Mol Biol. 2010 Jul;121(1-2):293-6. Epub 2010 Mar 19.
von Hurst PR, Stonehouse W, Kruger MC, Coad J.
Institute of Food, Nutrition and Human Health, Massey University, Private Bag 102 904, North Shore Mail Centre, Auckland, New Zealand. p.r.vonhurst at massey.ac.nz

There is a lack of evidence that improving vitamin D status, without changing calcium intake, has a positive effect on bone turnover as indicated by bone marker changes. The objective was to measure the effect of vitamin D supplementation, in vitamin D deficient women (25(OH)D concentration<50 nmol/L), on osteocalcin (OC) and C-telopeptide (CTX). The study design was a randomised controlled intervention administering 4000 IU vitamin D3 or placebo daily for 6 months to South Asian women, aged>20 years. Subjects were stratified by age and menopausal status. Median (25th, 75th percentile) serum 25(OH)D increased significantly from 21 (11, 40) to 75 (55, 84) nmol/L with supplementation. In women>49 years or postmenopausal (n=26), who were not supplemented (n=13), CTX and OC levels increased (P=0.001, P=0.004 respectively), indicating an increased rate of bone turnover. With supplementation CTX decreased (P=0.012) and there was no significant change in OC. In women who were under 49 years and premenopausal (n=55; 29 supplemented), there was no significant response to supplementation in either CTX or OC.

We conclude that correcting vitamin D deficiency in older women suppresses the age-induced increase in bone turnover and reduces bone resorption which would normally be exacerbated in conditions of low serum 25(OH)D. PMID: 20304051