[The effects of increased dietary calcium intake on bone mineral density in long-term lactating women, and recovery of bone loss caused by long-term lactation with low calcium diet].
OBJECTIVE
The purpose of this study was to examine the efficacy of an increased calcium (Ca) diet for preventing bone mineral loss in long-term lactating women, considering bone metabolism, and recovery of bone loss caused by long-term lactation with low dietary Ca intake.


METHODS
Two groups of long-term (> 12 mon.) lactating women ... one with an enhanced Ca intake (Group M, n = 22) and the other with diet feeding no cow's milk and no milk products (Group N, n = 16) ... and a control group of 21 non-lactating postpartum women (Group C) were studied. Bone mineral density (BMD) was measured by ultrasonic bone densitometry. Stiffness calculated from the combined value of speed of sound and broadband ultrasound attenuation was used as an index of BMD. BMD and bone metabolic markers in urine and serum (only M and C groups) were assessed from 1 approximately 12 weeks postpartum (initial) at six-month intervals for a maximum of two years and changes were compared among the groups.


RESULTS
1. The mean (+/- SD) dietary Ca intake was 1032 (209) mg/day in the M group. 2. After lactating for one year, the N group demonstrated significant decrease in BMD, with both 1 and 2 babies, whereas the M group had no significant change. 3. The BMD in the N group returned to initial levels at 0.5 approximately 1 year post-weaning, 4. In the N group, compared with the M group, the urinary Hydroxyproline/creatinine ratio was significantly higher at the initial measurement and half a year thereafter, while urinary Ca/ creatinine ratio was significantly lower after a year. However, there were no significant differences between the M and C groups. 5. Serum bone alkaline phosphatase was significantly higher in the M group compared with the C group.


CONCLUSIONS
Bone loss during long-term lactation can be prevented with adequate dietary Ca intake. Once lost, recovery to initial levels occurs 0.5 approximately 1 year post-weaning.
Yoneyama
Kyoko
K
Nara University of Education.
Ikeda
Junko
J
D000328:Adult; D015519:Bone Density; D001862:Bone Resorption / Q000378:metabolism; D001842:Bone and Bones / Q000378:metabolism; D001942:Breast Feeding; D002136:Calcium, Dietary / Q000008:administration & dosage*; D005260:Female; D006801:Humans; D007774:Lactation
D002136:Calcium, Dietary