Heaney R P, Recker R R, Stegman M R, Moy A J
Hard Tissue Research Center, Creighton University School of Medicine, Omaha, NE.
J Bone Miner Res. 1989 Aug;4(4):469-75. doi: 10.1002/jbmr.5650040404.
A total of 526 absorption studies, using both the double-isotope and balance-based methods, were performed in 189 middle-aged women in good general health. The study extended over 17 years of observation, with most subjects studied from two to four times at 5 year intervals. Each study was done on the woman's own self-selected calcium intake and was carried out under inpatient, metabolic balance controls. There was a highly significant inverse correlation between calcium intake and absorption fraction, with the best fit provided by an hyperbola in which absorption fraction is approximately inversely proportional to the square root of intake. The range of absorptive performance was very broad at all intake levels. Mean absorption fraction declined from a value of 0.45 at very low intakes (approximately 200 mg Ca per day) to approximately 0.15 at intakes above 2000 mg/day. There was a highly significant fall in absorption efficiency with age, amounting to approximately 0.0021 per year and a one-time decrease, amounting to approximately 0.022 at the time of menopausal estrogen loss.
对189名身体健康的中年女性进行了总共526项吸收研究，采用了双同位素法和基于平衡的方法。该研究持续了17年的观察期，大多数受试者每隔5年接受两到四次研究。每项研究都是基于女性自身选择的钙摄入量进行的，并在住院代谢平衡控制下进行。钙摄入量与吸收分数之间存在高度显著的负相关，双曲线能提供最佳拟合，其中吸收分数大约与摄入量的平方根成反比。在所有摄入量水平下，吸收性能的范围都非常广泛。平均吸收分数从极低摄入量（每天约200毫克钙）时的0.45降至摄入量高于2000毫克/天时的约0.15。吸收效率随年龄显著下降，每年约下降0.0021，在绝经后雌激素丧失时一次性下降约0.022。
