Changes in bone mineral density and markers of bone remodeling during lactation and postweaning in women consuming high amounts of calcium.

Department of Food Science and Human Nutrition, University of Missouri, Columbia, USA.

A randomized clinical intervention trial to determine effects of lactation and 1 g of calcium (Ca) on bone remodeling was conducted in 15 women (calcium = 7, placebo [P] = 8) consuming 1.3-2.4 g of Ca/day from diet + prenatal supplement. Study periods were baseline, < or = 2 weeks postpartum; lactation, 3 months lactation; and postweaning, 3 months postweaning. Bone mineral density (BMD) corrected for body weight was determined by dual-energy X-ray absorptiometry (DXA). Indicators of calcium metabolism, bone turnover, and lactation were measured: calcium metabolism, parathyroid hormone (PTH), 25-hydroxyvitamin D (25[OH]D), 1,25-dihydroxyvitamin D (1,25[OH]2D); bone turnover, formation, procollagen I carboxypeptides (PICP), osteocalcin, and bone alkaline phosphatase (B-ALP), resorption, tartrate resistant acid phosphatase (TRAP); and lactation, prolactin (PRL). Mean BMD changes differed by site: baseline to lactation -4.3% (P) (p < 0.04) and -6.3% (Ca) (p < 0.01) at the lumbar spine (L2-L4) and 5.7% gains of the ultradistal (UD) radius (Ca) (p < 0.04); lactation to postweaning, -6% to -11% at all sites of the radius and ulna (Ca, P) (p < 0.04) +3% at L2-L4 (Ca) (p < 0.03); baseline to postweaning, (UD) radius -5.2% (P) (p < 0.03), UD radius + ulna -6% to -8% (Ca, P) (p < 0.04) but no significant loss of L2-L4 or total body. Bone turnover markers were higher at lactation than postweaning: PICP (+34%, p < 0.001), osteocalcin (+25%, p < 0.01), TRAP (+11%, p < 0.005) as well as PRL (+81%, p < 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

PMID: 7502702 [PubMed - indexed for MEDLINE]