Soy isoflavones do not affect bone resorption in postmenopausal women: A dose-response study using a novel approach with41Ca

J. M.K. Cheong, B. R. Martin, G. S. Jackson, D. Elmore, G. P. McCabe, J. R. Nolan, S. Barnes, M. Peacock, C. M. Weaver

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50 Scopus citations


Introduction: The purpose of this 3-way crossover study was to identify the effective dose of soy protein isolate enriched with isoflavones for suppressing bone resorption in postmenopausal women using a novel, rapid assessment of antibone resorbing treatments. Methods: Thirteen postmenopausal women (≥6 yr since menopause) were predosed with 41Ca iv. After a 200-d baseline period, subjects were given 43 g soy protein/d that contained 0, 97.5, or 135.5 mg total isoflavones in randomized order. The soy protein isolate powder was incorporated into baked products and beverages. Each 50-d intervention phase was preceded by a 50-d pretreatment phase for comparison. Serum isoflavone levels and biochemical markers were measured at the end of each phase. Twenty-four-hour urine samples were collected approximately every 10 d during each phase for 41Ca/Ca analysis by accelerator mass spectrometry. Results: Serum isoflavone levels reflected the amount of isoflavones consumed in a dose-dependent manner. None of the isoflavone levels had a significant effect on biochemical markers of bone turnover, urinary cross-linked N teleopeptides of type I collagen and serum osteocalcin, or bone turnover as assessed by urinary 41Ca/Ca ratios. Conclusions: Soy protein with isoflavone doses of up to 135.5 mg/d did not suppress bone resorption in postmenopausal women. This is the first efficacy trial using the novel technique of urinary 41Ca excretion from prelabeled bone.

Original languageEnglish (US)
Pages (from-to)577-582
Number of pages6
JournalJournal of Clinical Endocrinology and Metabolism
Issue number2
StatePublished - Feb 2007


ASJC Scopus subject areas

  • Endocrinology, Diabetes and Metabolism
  • Biochemistry
  • Endocrinology
  • Clinical Biochemistry
  • Biochemistry, medical

Cite this

Cheong, J. M. K., Martin, B. R., Jackson, G. S., Elmore, D., McCabe, G. P., Nolan, J. R., Barnes, S., Peacock, M., & Weaver, C. M. (2007). Soy isoflavones do not affect bone resorption in postmenopausal women: A dose-response study using a novel approach with41Ca. Journal of Clinical Endocrinology and Metabolism, 92(2), 577-582.