Soy isoflavone intake inhibits bone resorption and stimulates bone formation in menopausal women: meta-analysis of randomized controlled trials.
OBJECTIVE
To clarify the effects of isoflavone intake on bone resorption and bone formation.


METHODS
We identified randomized controlled trials related to urinary deoxypyridinoline (Dpyr, a bone resorption marker) and serum bone-specific alkaline phosphatase (BAP, a bone formation marker) listed on MEDLINE (January 1966-April 2006), the Cochrane Controlled Trials Register, EMBASE (1985-January 2006), Science Citation Index and PUBMED (updated till April 2006).


RESULTS
Nine studies with a total of 432 subjects were selected for meta-analysis. The urinary Dpyr concentration in subjects who consumed isoflavones decreased significantly by -2.08 nmol/mmol (95% confidence interval (CI): -3.82 to -0.34 nmol/mmol) in comparison with that in subjects who did not consume isoflavones. Isoflavone intake vs placebo intake significantly increased serum BAP by 1.48 microg/l (95% CI: 0.22-2.75 mug/l). Decreases in the urinary Dpyr concentration with isoflavone intake of <90 mg/day and with treatment lasting less than 12 weeks were -2.34 nmol/mmol (95% CI: -4.46 to -0.22 nmol/mmol) and -2.03 nmol/mmol (95% CI: -3.20 to -0.85 nmol/mmol), respectively.


CONCLUSIONS
Isoflavone intervention significantly inhibits bone resorption and stimulates bone formation. These favorable effects occur even if <90 mg/day of isoflavones are consumed or the intervention lasts less than 12 weeks.
Ma
D-F
DF
Department of Social Medicine and Health Education, School of Public Health, Peking University, Beijing, China.
Qin
L-Q
LQ
Wang
P-Y
PY
Katoh
R
R
D000596:Amino Acids / Q000652:urine*; D001862:Bone Resorption / Q000517:prevention & control*; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology*; D008593:Menopause; D008875:Middle Aged; D010012:Osteogenesis / Q000187:drug effects* / Q000502:physiology; D015663:Osteoporosis, Postmenopausal / Q000517:prevention & control; D016032:Randomized Controlled Trials as Topic; D013025:Glycine max / Q000737:chemistry; D016896:Treatment Outcome
D000596:Amino Acids; D007529:Isoflavones; C036020:deoxypyridinoline