 This study will last 5 years and will comprise three populations: men with prostate cancer on androgen ablation therapy, postmenopausal women on hormone replacement therapy HRT, and postmenopausal women not on HRT. Participants will be randomly assigned to receive either isoflavone or placebo for two to four weeks. Participants serum and serum extracts will be incubated with cultured human cell lines prostate cancer, breast cancer and osteoblasts and estrogenic and non-estrogenic mechanisms of action investigated. The human sera data will be complemented by parallel studies of direct addition of crystalline isoflavones genistein, daidzein and equol to the same cultured human cell lines. Participants serum and urine also will be tested for markers of bone resorption and formation. Quality of life issues will be assessed with questionnaires. 