Isoflavones and Postmenopausal Bone Health: A Viable Alternative to Estrogen Therapy?

OBJECTIVE:The rapidly growing postmenopausal population in the United States, and this populationʼs high incidence and prevalence of osteoporosis and related morbidity and mortality herald an enormous public health burden for the coming decades. Estrogen replacement has been the mainstay of therapy for the prevention and treatment of osteoporosis in this estrogen-deficient population. However, long-term compliance with estrogen therapy generally is poor, and there are numerous concerns regarding its safety. The phytoestrogens are nonsteroidal plant-derived compounds that exhibit estrogenic activity at several sites. The isoflavones are one class of phytoestrogens derived largely from soy-based products. International popularity for menopausal therapy regimens containing isoflavones is growing rapidly. In this article, we review the existing data on isoflavones and postmenopausal bone health. DESIGN:A review of interventional trials examining isoflavones and bone in animals and humans. RESULTS:The data point to a reduction in bone resorption resulting from isoflavone/ ipriflavone intake. CONCLUSIONS:The data on naturally occurring isoflavones are very limited but suggest that including them in the diet results in a reduction in bone resorption caused by estrogen deficiency. The extensive data on ipriflavone. a synthetic isoflavone derivative, suggest that it is a useful and safe alternative to estrogen therapy in treating existing low bone mass or osteoporosis in postmenopausal women. Further studies are warranted to examine the utility of ipriflavone as a preventive agent, as well as the clinical efficacy of the naturally occurring isoflavones. (Menopause 1999;6:233-241. © 1999. The North American Menopause Society.)