Conlisk A J, Galuska D A
Biological and Biomedical Sciences Division, Nutrition and Health Sciences Program, Emory University, Atlanta, Georgia 30322, USA.
Prev Med. 2000 Nov;31(5):562-8. doi: 10.1006/pmed.2000.0742.
By increasing the urinary excretion of calcium, caffeine consumption may reduce bone mineral density (BMD) and subsequently increase the risk for osteoporotic fracture. Although negative associations between caffeine consumption and BMD have been reported for postmenopausal women, in particular for those who consume low amounts of dietary calcium, the relation between caffeine and BMD in younger women is unclear. Therefore, we evaluated the association between caffeine consumption and BMD in a cross-sectional study of 177 healthy white women, age 19-26 years, who attended a Midwestern university.
Average caffeine intake (milligrams per day) was calculated from self-reports of the consumption of coffee, decaffeinated coffee, tea, colas, chocolate products, and select medications during the previous 12 months (mean caffeine intake = 99. 9 mg/day). BMD (grams per square centimeter) at the femoral neck and the lumbar spine was measured by dual-energy X-ray absorptiometry.
After adjusting in linear regression models for potential confounders, including height, body mass index, age at menarche, calcium intake, protein consumption, alcohol consumption, and tobacco use, caffeine consumption was not a significant predictor of BMD. For every 100 mg of caffeine consumed, femoral neck BMD decreased 0.0069 g/cm(2) (95% confidence in terval [CI] = -0.0215, 0. 0076) and lumbar spine BMD decreased 0.0119 g/cm(2) (95% CI = -0. 0271, 0.0033). No single source of caffeine was significantly associated with a decrease in BMD. Furthermore, the association between caffeine consumption and BMD at either site did not differ significantly between those who consumed low levels of calcium (< or =836 mg/day) and those who consumed high levels of calcium (>836 mg/day).
Caffeine intake in the range consumed by young adult women is not an important risk factor for low BMD.
通过增加钙的尿排泄量，摄入咖啡因可能会降低骨矿物质密度（BMD），进而增加骨质疏松性骨折的风险。尽管已有报道称绝经后女性的咖啡因摄入量与骨密度之间存在负相关，尤其是那些膳食钙摄入量低的女性，但年轻女性中咖啡因与骨密度之间的关系尚不清楚。因此，我们在一项横断面研究中评估了177名年龄在19至26岁之间、就读于中西部一所大学的健康白人女性的咖啡因摄入量与骨密度之间的关联。
根据过去12个月内咖啡、脱咖啡因咖啡、茶、可乐、巧克力产品及特定药物的摄入情况的自我报告计算平均咖啡因摄入量（毫克/天）（平均咖啡因摄入量 = 99.9毫克/天）。采用双能X线吸收法测量股骨颈和腰椎的骨密度（克/平方厘米）。
在针对包括身高、体重指数、初潮年龄、钙摄入量、蛋白质摄入量、酒精摄入量和吸烟情况等潜在混杂因素进行线性回归模型调整后，咖啡因摄入量并非骨密度的显著预测因素。每摄入100毫克咖啡因，股骨颈骨密度降低0.0069克/平方厘米（95%置信区间[CI] = -0.0215，0.0076），腰椎骨密度降低0.0119克/平方厘米（95%CI = -0.0271，0.0033）。没有单一的咖啡因来源与骨密度降低显著相关。此外，钙摄入量低（≤836毫克/天）的人群和钙摄入量高（>836毫克/天）的人群中，咖啡因摄入量与任一部位骨密度之间的关联无显著差异。
年轻成年女性所摄入的咖啡因量范围内，并非低骨密度的重要风险因素。
