Jayo MJ, Anthony MS, Register TC, Rankin SE, Vest T, Clarkson TB. Dietary soy isoflavones and bone loss: a study in ovariectomized monkeys. Poster presented at the 18th Annual Meeting of the American Society for Bone and Mineral Research; August 1996. [abstract] J Bone Miner Res. 1996 Aug; 11(Suppl 1):S228.

Skeletally mature wild-caught ovariectomized cynornolgus macaques are a useful animal model to study potential therapies for estrogen-deficient osteopenia. An ongoing experiment was designed to evaluate the effectiveness of soy-based diets rich in isoflavone content (genistein and daidzein) in protecting against osteopenia and diet-induced coronary artery atherosclerosis. Monkeys were ovariectomized and divided into three diet groups: 1) an isofuvone-poor soy-based diet (Soy(-),n= 16), 2) an isofuvone-rich soy-based diet (Soy(+), n=22), and 3) an isofuvone-poor soy-based diet plus Premarinm (ERT,n=20). No effects on body weight were seen. Lumbar spine bone mineral content (BMCsp) and whole body mineral content (BMCw) were measured at baseline, 11 and 23 months after ovariectomy. After 23 mo, both the Soy(-) and Soy(+) animals had lost significant (p less than 0.05) BMCsp from baseline values (-4.6% and -6.7%. respectively). In contrast, the ERT group BMCsp was comparable to baseline (+1.8%). A similar pattern was observed in BMCw in all three groups (-0.8%,-4.0%, and +7.8%, respectively). Serum levels of total alkaline phosphatase (ALP), acid phosphatase (ACP), and tartrate-resistant ACP (TRAP, all UIL) were measured at baseline, 4, 11, 18 and 23 months after ovariectomy. After 23 mo, ERT animals continued to have the lowest blood levels of ALP (243.9514.5, 214.4515.3, and 126.3k7.9, respectively), and tended to have lower ACP and TRAP levels, but these did not differ among groups. In surgically postmenopausal monkeys, isoflavone-rich diets may not be as effective as ERT in protecting against estrogen-deficient osteopenia.

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