Cholecalciferol Supplementation Promotes Bone Turnover in Chinese Adults with Vitamin D Deficiency.

ABSTRACT

BACKGROUND: Bone turnover markers (BTMs) are proposed as alternative indicators for bone mineral density in diagnosis and management of osteoporosis. However, little is known about the effects of vitamin D supplementation on BTMs in nonwhite populations. OBJECTIVE: We aimed to investigate the responses in BTMs after vitamin D supplementation in Asians. METHODS: In this secondary data analysis of a randomized, double-blind, placebo-controlled trial, 448 Chinese adults [mean ± SD age 31.9 ± 8.0 y; mean ± SD body mass index (kg/m2) 22.1 ± 2.6; 69% were women] with vitamin D deficiency (serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L) received 2000 IU/d cholecalciferol or placebo for 20 wk. Serum concentrations of 25(OH)D, parathyroid hormone (PTH), calcium, and markers of bone formation and resorption were measured at weeks 0 and 20. Intention-to-treat analysis was applied, and between-group differences were compared by general linear models with adjustments. RESULTS: Cholecalciferol supplementation increased the serum bone alkaline phosphatase (BALP) concentration (+1.7 ± 1.9 µg/L) significantly more than placebo (+1.1 ± 1.7 µg/L; P = 0.004), but not circulating concentrations of procollagen type I N-terminal propeptide (PINP), ß-isomerized C-terminal telopeptide of type I collagen (ß-CTX), or tartrate-resistant acid phosphatase 5b (TRAP5b) (P ≥ 0.53). Notably, a pooled analysis indicated that changes in serum 25(OH)D were positively associated with changes in serum BALP, PINP, and TRAP5b (r = 0.07-0.16, P ≤ 0.02), but inversely with changes in PTH (r = -0.15, P < 0.001). Among cholecalciferol-treated participants, individuals who achieved serum 25(OH)D ≥75 nmol/L had greater increases in serum ß-CTX (224% compared with 146%; P = 0.02) and TRAP5b (22.2% compared with 9.1%; P = 0.007), but smaller decreases in serum calcium (-1.3% compared with -1.9%; P = 0.005) and calcium-phosphorus product (-2.6% compared with -3.3%; P = 0.02) compared with those with serum 25(OH)D <75 nmol/L. CONCLUSIONS: Daily supplementation with 2000 IU cholecalciferol for 20 wk may promote bone formation in Chinese adults with vitamin D deficiency. More studies are needed to elucidate the potential clinical implications of BTMs.This trial was registered at clinicaltrials.gov as NCT01998763.