Antiresorptive effects of phytoestrogen supplements compared with estradiol or risedronate in postmenopausal women using (41)Ca methodology

J Clin Endocrinol Metab. 2009 Oct;94(10):3798-805. doi: 10.1210/jc.2009-0332. Epub 2009 Jul 7.

Abstract

Introduction: Reduction of ovarian estrogen secretion at menopause increases net bone resorption and leads to bone loss. Isoflavones have been reported to protect bone from estrogen deficiency, but their modest effects on bone resorption have been difficult to measure with traditional analytical methods.

Methods: In this randomized-order, crossover, blinded trial in 11 healthy postmenopausal women, we compared four commercial sources of isoflavones from soy cotyledon, soy germ, kudzu, and red clover and a positive control of oral 1 mg estradiol combined with 2.5 mg medroxyprogesterone or 5 mg/d oral risedronate (Actonel) for their antiresorptive effects on bone using novel (41)Ca methodology.

Results: Risedronate and estrogen plus progesterone decreased net bone resorption measured by urinary (41)Ca by 22 and 24%, respectively (P < 0.0001). Despite serum isoflavone profiles indicating bioavailability of the phytoestrogens, only soy isoflavones from the cotyledon and germ significantly decreased net bone resorption by 9% (P = 0.0002) and 5% (P = 0.03), respectively. Calcium absorption and biochemical markers of bone turnover were not influenced by interventions.

Conclusions: Dietary supplements containing genistein-like isoflavones demonstrated a significant but modest ability to suppress net bone resorption in postmenopausal women at the doses supplied in this study over a 50-d intervention period.

Publication types

  • Comparative Study
  • Randomized Controlled Trial
  • Research Support, N.I.H., Extramural

MeSH terms

  • Aged
  • Analysis of Variance
  • Bone Density Conservation Agents / pharmacology
  • Bone Density Conservation Agents / therapeutic use*
  • Bone Resorption / prevention & control*
  • Calcium / metabolism
  • Calcium Radioisotopes / metabolism*
  • Cotyledon
  • Cross-Over Studies
  • Dietary Supplements*
  • Estradiol / pharmacology
  • Estradiol / therapeutic use*
  • Etidronic Acid / analogs & derivatives*
  • Etidronic Acid / pharmacology
  • Etidronic Acid / therapeutic use
  • Female
  • Genistein / pharmacology
  • Genistein / therapeutic use
  • Humans
  • Isoflavones / blood
  • Isoflavones / pharmacology
  • Isoflavones / therapeutic use*
  • Linear Models
  • Medroxyprogesterone / pharmacology
  • Medroxyprogesterone / therapeutic use*
  • Middle Aged
  • Osteoporosis, Postmenopausal / prevention & control*
  • Phytoestrogens / pharmacology
  • Phytoestrogens / therapeutic use*
  • Plant Preparations / pharmacology
  • Plant Preparations / therapeutic use
  • Pueraria
  • Risedronic Acid
  • Single-Blind Method
  • Soybeans
  • Treatment Outcome
  • Trifolium

Substances

  • Bone Density Conservation Agents
  • Calcium Radioisotopes
  • Isoflavones
  • Phytoestrogens
  • Plant Preparations
  • Estradiol
  • Genistein
  • Medroxyprogesterone
  • Risedronic Acid
  • Etidronic Acid
  • Calcium