Biochemical markers of calcium and bone metabolism during 18 months of lactation in Gambian women accustomed to a low calcium intake and in those consuming a calcium supplement

Ann Prentice, Landing M. A. Jarjou, Dorothy M. Stirling, Rochelle Buffenstein, Susan Fairweather-Tait

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The effect of 18 months of lactation on indexes of calcium and bone metabolism was studied in 60 Gambian women accustomed to a very low calcium intake. Half the women consumed a calcium supplement from 10 days postpartum for 52 weeks (supplement, 714 mg Ca/day; total Ca intake, 992 +/- 114 mg/day), and half consumed placebo (total Ca intake, 288 +/- 128 mg/day). Fasting blood and 24-h urine samples were collected at 1.5, 13, 52, and 78 weeks of lactation and analyzed for calciotropic hormones (intact PTH, 1,25-dihydroxyvitamin D, and calcitonin), bone turnover markers (osteocalcin, bone alkaline phosphatase, and urinary deoxypyridinoline), and plasma minerals (calcium and phosphate). The first months of lactation were associated with increased bone turnover and plasma phosphate, and decreased PTH and 1,25-dihydroxyvitamin D. These effects diminished by 52 weeks, although breast milk volumes remained high. The Gambians had higher PTH, 1,25-dihydroxyvitamin D, and bone formation than British women with a greater customary calcium intake. None of the biochemical indexes was affected by calcium supplementation, with the possible exception of bone alkaline phosphatase (-29% at 52 weeks; P = 0.015). These data demonstrate that lactation-associated changes in calcium and bone metabolism are physiological and are independent of dietary calcium supply in women with very low calcium intakes.
Original languageEnglish
Pages (from-to)1059-1066
Number of pages8
JournalThe Journal of Clinical Endocrinology and Metabolism
Issue number4
Publication statusPublished - Apr 1998


  • Adolescent
  • Adult
  • Aging
  • Analysis of Variance
  • Biological Markers
  • Bone Density
  • Bone and Bones
  • Calcium
  • Dietary Supplements
  • Dose-Response Relationship, Drug
  • Double-Blind Method
  • Female
  • Gambia
  • Great Britain
  • Humans
  • Lactation
  • Milk, Human
  • Seasons

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