Effects of soy isoflavones on markers of bone turnover in premenopausal and postmenopausal women

Kerry E. Wangen, Alison M. Duncan, Barb E. Merz-Demlow, Xia Xu, Robert Marcus, William R. Phipps, Mindy S. Kurzer

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152 Scopus citations

Abstract

Soy isoflavones are hypothesized to exert hormonal effects in women and thus may play a role in bone metabolism throughout life. In 2 randomized, cross-over studies, 14 pre- and 17 postmenopausal women were given 3 soy protein isolates containing different amounts of isoflavones [control, 0.13; low isoflavone (low-iso), 1.00; and highiso, 2.01 mg/kg body wt·day, averaging 8, 65, and 130 mg/day, re-spectively], for over 3 months each. Food records, blood samples, and 24-h urine collections were obtained throughout the studies. The endpoints evaluated included plasma or serum concentrations of bone-specific alkaline phosphatase, osteocalcin, insulin-like growth factor-I (IGFI), IGF binding protein-3 (IGFBP3), and urine concentrations of deoxypyridinoline cross-links and carboxy-terminal telopeptide of type I collagen. In premenopausal women, IGFI and IGFBP3 concentrations were increased by the low-iso diet, and deoxypyridinoline cross-links was increased by both the low- and highiso diets during certain phases of the menstrual cycle. In postmenopausal women, bone-specific alkaline phosphatase was decreased by both the low- and high-iso diets, and there were trends toward decreased osteocalcin, IGFI, and IGFBP3 concentrations with increasing isoflavone consumption. Although soy isoflavones do affect markers of bone turnover, the changes observed were of small magnitude and not likely to be clinically relevant. These data do not support the hypothesis that dietary isoflavones per se exert beneficial effects on bone turnover in women.

Original languageEnglish (US)
Pages (from-to)3043-3048
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Volume85
Issue number9
DOIs
StatePublished - 2000

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