Abstract | CONTEXT: Questions regarding the superiority of free and bioavailable 25-hydroxyvitamin D [25( OH)D] in predicting health outcomes remain unresolved. OBJECTIVE: This study investigates the impact of vitamin D variables-total, bioavailable, or free 25(OH)D-on indices of bone and mineral metabolism, at baseline and in response to 2 vitamin D doses. DESIGN: Our objectives are implemented as exploratory analyses on data collected in a 1-year, double-blind, randomized controlled trial completed in July 2014. SETTING: Participants were recruited from 3 major hospitals in an ambulatory setting. PARTICIPANTS: Participants were >65 years of age, overweight, and had a baseline serum 25( OH)D between 10 and 30 ng/mL. A total of 221 participants completed the study. INTERVENTION: Subjects were randomized to receive calcium and oral vitamin D3 (600 IU/day or 3750 IU/day) supplementation. RESULTS: Participants who received the higher vitamin D dose had levels that were 1.3- to 1.4-fold higher than those taking the lower dose, for all variables (P value < 0.001). Serum values of bioavailable and free 25( OH)D were associated with total 25( OH)D, with r values of 0.942 and 0.943, respectively (P value < 0.001). Parathyroid hormone (PTH) was negatively associated with all vitamin D variables, with correlation coefficients ranging from -0.22 to -0.25, while calcium and bone turnover markers (carboxy-terminal collagen crosslinks and osteocalcin) did not. Only total 25( OH)D had a positive relationship with % change bone mineral density (BMD) at the femoral neck at 12 months, while only free and bioavailable 25( OH) had a positive relationship with % change total body BMD at 12 months. CONCLUSION: Calculated free and bioavailable 25( OH)D do not appear to be superior to total 25( OH)D in predicting indices of bone health in an elderly population.
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Authors | Malak El Sabeh, Paola Ghanem, Laila Al-Shaar, Maya Rahme, Rafic Baddoura, Georges Halaby, Ravinder J Singh, Dirk Vanderschueren, Roger Bouillon, Ghada El-Hajj Fuleihan |
Journal | The Journal of clinical endocrinology and metabolism
(J Clin Endocrinol Metab)
Vol. 106
Issue 2
Pg. e990-e1001
(01 23 2021)
ISSN: 1945-7197 [Electronic] United States |
PMID | 33280041
(Publication Type: Journal Article, Randomized Controlled Trial, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)
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Copyright | © The Author(s) 2020. Published by Oxford University Press on behalf of the Endocrine Society. All rights reserved. For permissions, please e-mail: [email protected]. |
Chemical References |
- Biomarkers
- Vitamins
- Vitamin D
- 25-hydroxyvitamin D
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Topics |
- Aged
- Biomarkers
(blood)
- Bone Density
- Double-Blind Method
- Female
- Follow-Up Studies
- Humans
- Male
- Prognosis
- Vitamin D
(analogs & derivatives, blood)
- Vitamins
(blood)
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