Effects of Calcium Supplementation on Calcium Homeostasis and BoneTurnover in Lactating Women

Document Type

Article

Publication Date

2-1-1999

Keywords

Adult, Amenorrhea, Amino Acids, Bone Remodeling, Calcitriol, Calcium, Dietary Supplements, Double-Blind Method, Female, Homeostasis, Humans, Lactation, Osteocalcin, Parathyroid Hormone, Peptide Fragments, Placebos, Postpartum Period, Procollagen, Weaning

Abstract

Lactation is a time of calcium flux, because women secrete approximately 210 mg calcium/day in breast milk, and they experience a transient bone loss. The objectives of this study were to determine the effect of calcium supplementation on adaptive responses in calcium homeostasis during lactation and after weaning. Two cohorts of women participated in a 6-month randomized calcium supplementation trial. Lactation cohort women (97 lactating, 99 nonlactating) were studied during the first 6 months post partum, and weaning cohort women (95 lactating, 92 nonlactating) were studied during the second 6 months post partum. Lactating women in the weaning cohort weaned approximately 1.5 months after enrollment. PTH was 18-30% lower in lactating than in nonlactating women (P < 0.01). Serum 1,25-dihydroxyvitamin D was 11-16% higher in lactating than in nonlactating women and remained elevated for approximately 1.5 months after weaning (P = 0.06). Calcium supplementation decreased serum PTH and 1,25-dihydroxyvitamin D in lactating and nonlactating women similarly. At 6 months, the calciuric response to calcium supplementation was less in lactating (compared with nonlactating) women (P = 0.06). Biomarkers of bone turnover were higher in lactating than in nonlactating women during lactation and after weaning but were not effected by calcium supplementation. Calcium supplementation has little effect on lactation-induced changes in the calcium economy.

Publication Title

The Journal of Clinical Endocrinology and Metabolism

Volume

84

Issue

2

First Page

464

Last Page

470

DOI of Published Version

10.1210/jcem.84.2.5451

PMID

10022402

Publisher

Endocrine Society

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