Phase I Clinical Study of Soy Isoflavones in Healthy, Post-Menopausal Women

Inclusion Criteria: * Performance status 0, 1, or 2 on ECOG scale * Acceptable hematopoietic, hepatic, and renal function (WBC≥3500 µL, platelet count ≥ 100,000/ml, serum creatinine \< 2.0 mg/dl, serum bilirubin ≤ 2.0 mg/dl, transaminases \< two times normal limits) * Post-menopausal status - FSH level \> 27 mIU/ml, no spontaneous bleeding \> 1 year * Normal mammogram within the last 13 months * Normal Papanicolaou Test within the last 13 months Exclusion Criteria: * Serious intercurrent medical illnesses or history of seizure * Significant cardiac disease (New York Heart Association Class III or IV) * Abnormalities on the physical examination screen including significant abnormality of the heart, lungs, liver, spleen, or other abdominal organs, or neurologic abnormality Abnormalities on the biochemical screen that could be metabolically significant * Individuals with intermediate equol values (\> 10 ug/L to \< 20 ug/L) on soy challenge * Use of antibiotics within the last 3 months * Use of hormone/estrogen therapy or SERMs within the last 3 months * Abnormal thyroid or endocrine function tests; or current use of thyroid medication * BMI at or above 35 * History of complete hysterectomy or oophorectomy * High risk of breast cancer (5-year risk of \>1.9%) based on NCI's Breast Cancer Risk Assessment Tool * A history of a malignancy active or initially diagnosed within 2 years other than curatively treated non-melanoma carcinoma of the skin * History of substance abuse or ad…