Calcium absorption in women: Relationships to Calcium intake, Estrogen status, and age
Article first published online: 3 DEC 2009
Copyright © 1989 ASBMR
Journal of Bone and Mineral Research
Volume 4, Issue 4, pages 469–475, August 1989
How to Cite
Heaney, R. P., Recker, R. R., Stegman, M. R. and Moy, A. J. (1989), Calcium absorption in women: Relationships to Calcium intake, Estrogen status, and age. J Bone Miner Res, 4: 469–475. doi: 10.1002/jbmr.5650040404
- Issue published online: 3 DEC 2009
- Article first published online: 3 DEC 2009
- Manuscript Revised: 24 MAR 1989
- Manuscript Accepted: 24 MAR 1989
- Manuscript Received: 24 JAN 1989
- PHS. Grant Number: AR07912
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.