Soy isoflavone intake increases bone mineral density in the spine of menopausal women: meta-analysis of randomized controlled trials.
OBJECTIVE
The effects of isoflavones on bone loss appear inconsistent in randomized controlled trials. Therefore, we used a statistical method of combining these diverse data to clarify the effects of soy isoflavone intake on spine bone loss.


METHODS
We identified randomized controlled trials related to the effects of soy isoflavone intake on spine bone mineral density or spine bone mineral content and performed meta-analysis with Review Manager 4.2 software.


RESULTS
Ten studies with a total of 608 subjects were selected for meta-analysis. The spine bone mineral density in subjects who consumed isoflavones increased significantly by 20.6 mg/cm(2) (95% confidence interval: 4.5-36.6 mg/cm(2)) in comparison to that in subjects who did not consume isoflavones. Isoflavone intake vs placebo intake increased spine bone mineral content by 0.93 g (95% confidence interval: -0.37 to 2.24 g) with borderline significance. Increases in the spine bone mineral density with isoflavone intake of more than 90 mg/day and with treatment lasting 6 months were 28.5mg/cm(2) (95% confidence interval: 8.4-48.6 mg/cm(2)) and 27 mg/cm(2) (95% confidence interval: 8.3-45.8 mg/cm(2)), respectively.


CONCLUSIONS
Isoflavone intervention significantly attenuates bone loss of the spine in menopausal women. These favorable effects become more significant when more than 90 mg/day of isoflavones are consumed. And soy isoflavone consumption for 6 months can be enough to exert beneficial effects on bone in menopausal women.
Department of Social Medicine & Health Education, School of Public Health, Peking University, Beijing 100083, PR China.
De-Fu
DF
Ma
Li-Qiang
LQ
Qin
Pei-Yu
PY
Wang
Ryohei
R
Katoh
D015519:Bone Density / Q000187:drug effects*; D005260:Female; D006801:Humans; D007529:Isoflavones / Q000494:pharmacology*; D008593:Menopause; D008875:Middle Aged; D015663:Osteoporosis, Postmenopausal / Q000188:drug therapy*; D016032:Randomized Controlled Trials as Topic; D013025:Glycine max / Q000737:chemistry*; D013997:Time Factors; D016896:Treatment Outcome
D007529:Isoflavones