To clarify the effects of soy isoflavone intake on bone loss, meta-analysis of randomized controlled trials (RCTs) was performed.
RCTs that observed the effects of soy isoflavone intake on urinary deoxypyridinoline (Dpyr), serum bone-specific alkaline phosphatase (BAP), and spine bone mineral density (SBMD) were searched by MEDLINE, CNKI, and so on. Meta-analysis for the RCTs selected in the analysis was performed.
Eighteen studies with a total of 978 subjects were selected for the analysis. The urinary Dpyr concentration in subjects who consumed isoflavones significantly decreased by - 2.08 nmol/mmol (95% CI: -3.82 - 0.34) in comparison to that in subjects who did not consume isoflavones. However, isoflavone intake significantly increased serum BAP by 1.48 microg/L (95% CI: 0.22 - 2.75). The SBMD in subjects who consumed isoflavones increased significantly by 20.6 mg/cm2 (95% CI: 4.5 - 36.6). Subjects who consumed isoflavone more than 90 mg/day and or 6 months increased SBMD as 28.5 mg/cm2 (95% CI: 8.4 - 48.6) and 27 mg/cm2 (95% CI: 8.3 - 45.8), respectively.
It was suggested that the bone loss in menopausal women attenuated by isoflavone intervention could be associated with inhibition of bone resorption and stimulation of bone formation.