Hall S L, Greendale G A
Loma Linda University School of Medicine, Loma Linda, California, USA.
Calcif Tissue Int. 1998 Sep;63(3):183-9. doi: 10.1007/s002239900512.
Ascorbic acid is a required cofactor in the hydroxylations of lysine and proline necessary for collagen formation; its role in bone cell differentiation and formation is less well characterized. This study examines the cross-sectional relation between dietary vitamin C intake and bone mineral density (BMD) in women from the Postmenopausal Estrogen/Progestin Interventions Trial. BMD (spine and hip) was measured using dual energy X-ray absorptiometry (DXA). The PEPI participants (n = 775) included in this analysis were Caucasian and ranged in age from 45 to 64 years. At the femoral neck and total hip after adjustment for age, BMI, estrogen use, smoking, leisure physical activity, calcium and total energy intake, each 100 mg increment in dietary vitamin C intake, was associated with a 0. 017 g/cm2 increment in BMD (P = 0.002 femoral neck; P = 0.005 total hip). After adjustment, the association of vitamin C with lumbar spine BMD was similar to that at the hip, but was not statistically significant (P = 0.08). To assess for effect modification by dietary calcium, the analyses were repeated, stratified by calcium intake (>500 mg/day and </=500 mg/day). For the femoral neck, women with higher calcium intake had an increment of 0.0190 g/cm2 in BMD per 100 mg vitamin C (P = 0.002). No relation between BMD and vitamin C was evident in the lower calcium stratum. Similar effect modification by calcium was observed at the total hip: the beta coefficient in the higher calcium stratum was similar to that for the total sample (beta = 0.0172, P = 0.01), but no statistically significant relation between total hip BMD and vitamin C was found in the lower calcium subgroup. Although the relation between vitamin C and lumbar spine BMD was of marginal statistical significance in the total sample, among women ingesting higher calcium, a statistically significant association was observed (beta = 0.0199, P = 0.024). These data are consistent with a positive association of vitamin C with BMD in postmenopausal women with dietary calcium intakes of at least 500 mg.
抗坏血酸是胶原蛋白形成过程中赖氨酸和脯氨酸羟化反应所需的辅助因子；其在骨细胞分化和形成中的作用尚不太明确。本研究在绝经后雌激素/孕激素干预试验的女性中，考察了膳食维生素C摄入量与骨矿物质密度（BMD）之间的横断面关系。使用双能X线吸收法（DXA）测量BMD（脊柱和髋部）。纳入本分析的PEPI参与者（n = 775）为白种人，年龄在45至64岁之间。在调整年龄、体重指数、雌激素使用情况、吸烟状况、休闲体育活动、钙和总能量摄入量后，膳食维生素C摄入量每增加100 mg，股骨颈和全髋部的BMD分别增加0.017 g/cm²（股骨颈：P = 0.002；全髋部：P = 0.005）。调整后，维生素C与腰椎BMD的关联与髋部相似，但无统计学意义（P = 0.08）。为评估膳食钙的效应修正作用，按钙摄入量（>500 mg/天和≤500 mg/天）分层重复分析。对于股骨颈，钙摄入量较高的女性，每100 mg维生素C使BMD增加0.0190 g/cm²（P = 0.002）。在低钙组中，未发现BMD与维生素C之间存在关联。在全髋部也观察到类似的钙效应修正作用：高钙组的β系数与总样本相似（β = 0.0172，P = 0.01），但在低钙亚组中，未发现全髋部BMD与维生素C之间存在统计学显著关联。尽管在总样本中维生素C与腰椎BMD之间的关系具有边缘统计学意义，但在摄入较高钙的女性中，观察到了统计学显著关联（β = 0.0199，P = 0.024）。这些数据表明，在膳食钙摄入量至少为500 mg的绝经后女性中，维生素C与BMD呈正相关。
