Tai and colleagues  have recently reported that treatment with 300 mg/day of isoflavones (aglycone equivalents) (172.5 mg genistein + 127.5 mg daidzein) for 2 years failed to prevent lumbar spine and total proximal femur bone mineral density (BMD) from declining, as compared with the placebo group. This randomized, double-blind, two-arm-designed study was conducted in a clinical sample of 431 postmenopausal women aged 45–65 years in three centers of Taipei (Taiwan). Each participant also ingested 600 mg of calcium and 125 IU of vitamin D per day. The BMD of the lumbar spine and total proximal femur were measured using dual-energy X-ray absorptiometry at baseline and every half-year thereafter. Serum bone-specific alkaline phosphatase, urinary N-telopeptide of type 1 collagen/creatinine, and other safety assessments were examined regularly. Serum concentrations of isoflavone metabolites, genistein and daidzein, in the intervention group were remarkably elevated following intake of isoflavones ([i]p[/i] < 0.001). However, differences in the mean percentage changes of BMD throughout the treatment period were not statistically significant (lumbar spine, [i]p[/i] = 0.42; total femur, [i]p[/i] = 0.39) between the isoflavone and placebo groups. A significant time trend of bone loss was observed at both sites following repeated measurement of BMD ([i]p[/i] < 0.001). Differences in bone marker levels were not significant between the two treatment groups. The authors concluded that treatment with 300 mg/day isoflavones (aglycone equivalents) failed to prevent a decline in BMD in the lumbar spine or total femur compared with the placebo group.
Ob Gyn Senior Consultant, Hospital Clínic Barcelona, and Full Professor, University of Barcelona, Spain
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