The effects of estrogen depletion and isoflavones on bone metabolism in rats

To examine a potential role for phytoestrogens in postmenopasual bone loss, the ovariectomized (OVX) rat model has been used to investigate whether lower than previously used doses of isoflavones are beneficial in impeding ovarian hormone deficiency-associated bone loss. In this study, thirty-two 90-day-old Sprague-Dawley rats were randomly divided into four groups and fed a semi-purified diet with or without isoflavones for forty days. The treatment groups were sham-operated (sham), OVX, OVX+ isoflavones (0.575 mg/g of dietary protein), and OVX+ isoflavones (1.15 mg/g of dietary protein). Ovariectomy reduced (P < 0.05) 4th lumbar vertebral, tibial, and femoral bone density, and femoral bone strength; increased (P < 0.05) urinary excretion of Ca; and did not affect serum Ca and Mg, blood ionized Ca, or urinary Mg excretion when compared with the sham group. We concluded that dietary supplementation of isoflavones at the two doses given had no effect on bone quality or other parameters of bone metabolism.