Isoflavones and skeletal health: are these molecules ready for clinical application?

A review of the recent literature on the effects of isoflavones was undertaken to determine whether molecules such as genistein and daidzein, aglycone derivatives of soybeans, might have benefit in the prevention and treatment of osteoporosis. The current standard for science-based medicine is the documentation of efficacy of an agent under controlled, randomized, prospective conditions. A few short clinical investigations have been undertaken using isoflavones (along with soy protein), but they had limitations in study design, and the numbers of women studied were small. Other evidence from animal models, in vitro experiments, and epidemiological reports suggest that the isoflavones have skeletal benefits in women with little or no ovarian estrogen production. A clear need exists for prospective human trials, using the required conditions of randomized clinical trials and designs, to satisfy objectively the needs for science-based medicine and for appropriate clinical applications.