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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 mug/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 less than 90 mg/day of isoflavones are consumed or the intervention lasts less than 12 weeks.
Source: European Journal of Clinical Nutrition. Feb 2008 vol 62, #2. PMID: 17392695, by Ma DF, Qin LQ, Wang PY, Katoh R. Department of Social Medicine and Health Education, School of Public Health, Peking University, Beijing, China; Department of Human Pathology, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan. [E-mail: Prof. P-Y Wang G06DA006@ccn.yamanashi.ac.jp]