Decreased bone resorption with soy isoflavone supplementation in postmenopausal women.
OBJECTIVE
To investigate the effect of soy isoflavone supplementation on bone mineral density (BMD) and markers of bone turnover in postmenopausal women.


METHODS
In this randomized, placebo-controlled clinical trial, we used a crossover design to test the effect of soy isoflavone (110 mg/day) (1.3:1.0:0.22 ratio of genistein/daidzein/ glycitein) on bone formation, bone resorption, bone mineral content (BMC), and BMD for 6 months.


RESULTS
Postmenopausal women (n = 19), mean age 70.6 +/- 6.3 years and mean time since menopause 19.1 +/- 5.5 years, were given isoflavone supplements for 6 months. There was a 37% decrease in urinary concentrations of type 1 collagen alpha1-chain helical peptide (HP), a marker of bone resorption, during the isoflavone supplementation compared with baseline (p < 0.05) and a significant difference in mean (SE) HP excretion levels when isoflavone was compared with placebo (43.4 +/- 5.2 vs. 56.3 +/- 7.2 microg/mmol creatinine [cr], p < 0.05). With isoflavone supplementation, mean spine BMD at L2 and L3 was significantly greater when treatment was compared with control, with a difference between means of 0.03 +/- 0.04 g and 0.03 +/- 0.04 g (p < 0.05), respectively. There were nonsignificant increases from baseline for total spine BMC (3.5%), total spine BMD (1%), total hip BMC (3.6%), and total hip BMD (1.3%) with the isoflavone treatment.


CONCLUSIONS
Soy isoflavone, in isolated form, was effective in this study to significantly decrease bone resorption in postmenopausal women. Further investigation needs to be done to evaluate the long-term effects of soy isoflavone on bone mass and fracture risk.
Harkness
Laura S
LS
Case Western Reserve University, Cleveland, Ohio 44109, USA. lharkness@metrohealth.org
Fiedler
Karen
K
Sehgal
Ashwini R
AR
Oravec
Dubravka
D
Lerner
Edith
E
D000368:Aged; D000369:Aged, 80 and over; D015415:Biomarkers / Q000378:metabolism; D015519:Bone Density / Q000187:drug effects*; D001862:Bone Resorption / Q000188:drug therapy* / Q000517:prevention & control; D018592:Cross-Over Studies; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage*; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control*; D017698:Postmenopause; D012307:Risk Factors; D030262:Soybean Proteins / Q000008:administration & dosage*; D013997:Time Factors; D016896:Treatment Outcome
D015415:Biomarkers; D007529:Isoflavones; D030262:Soybean Proteins