Using Soy Estrogens to Prevent Bone Loss and Other Menopausal Symptoms

The risks of bone loss and osteoporosis increase significantly after menopause. Although hormone therapy (HT) can spare menopausal women from bone loss and other menopausal symptoms, Women's Health Initiative (WHI) findings indicate significant potential health risks associated with HT. This has prompted women to switch from HT to naturally occurring compounds similar to estrogen, such as those derived from soy, in the hope that estrogens from plant sources can provide benefits while sparing adverse effects caused by prescribed estrogens. However, the long-term efficacy and safety of plant estrogens are unknown. This study will evaluate the effectiveness of treatment using purified soy isoflavones, a dietary source of phytoestrogens, in preventing bone loss, menopausal symptoms, and other changes associated with estrogen deficiency in young menopausal women. The "Soy Phytoestrogens As Replacement Estrogen (SPARE)" study will provide a foundation of knowledge from which menopausal women and their doctors can begin to make more informed decisions regarding HT and other treatment options.

Enrollment into the study will occur over 3 years, with each participant taking part in the study for a total of 2 years. Participants will be randomly assigned to one of two groups; the first group will receive a 200 mg dose of soy isoflavones daily and the second group will receive placebo daily. There will be 10 study visits: screening, study entry, randomization at Month 1, six follow-up visits at Months 2, 4, 8, 12, 16, 20, and a final visit at the end of active participation at Month 24. At each study visit, participants will have blood drawn, provide urine samples, answer questionnaires, and have mammograms and bone density tests.

Inclusion criteria

• Absence of menstrual period for 12 months but not more than 5 years, or absence of menstrual period for 6 to 12 months and follicle stimulating factor (FSH) greater than 40 IU/L

Exclusion criteria

• Treatment with estrogens, progesterone, raloxifene, or tamoxifen
• Treatment with bisphosphonates, calcitonin, fluoride, or systemic corticosteroids
• Use of soy/herbal supplements, including DHEA, within 3 months prior to study entry
• Use of antibiotics in the month prior to study entry
• Use of prescription medication to treat hot flashes
• Chemical menopause, including post-chemotherapy
• Hyperthyroidism
• Hypothyroidism
• Uncontrolled diabetes
• Malabsorption syndromes or other chronic diseases
• Body mass index (BMI) less than 20 or greater than 32
• Bone mineral density (BMD) T-score below -2.0 in lumbar spine or femoral neck