Isoflavones for Promoting Calcium Absorption and Preventing Bone Loss in Post Menopausal Women

National Center for Complementary and Integrative Health (NCCIH), Office of Dietary Supplements (ODS)

Estrogen is a hormone that helps prevent calcium loss and bone breakdown. During menopause, estrogen levels decrease. Insufficient amounts of estrogen may lead to bone loss and possibly osteoporosis. Isoflavones are natural compounds found in soy plants that may help provide protection against bone loss. This study will evaluate the effect of soy isoflavones on calcium absorption and bone loss in post menopausal women.

Estrogen is a hormone that activates bone-forming cells and prevents calcium loss and bone breakdown. During menopause, estrogen levels decrease. Insufficient amounts of estrogen may accelerate bone breakdown and inhibit the body's ability to create new bone, thereby leading to bone loss and possibly osteoporosis. Various treatments have been developed to decrease bone loss in post-menopausal women. Actonel, for example, is an FDA-approved drug used to help prevent bone loss. Phytoestrogens are plant compounds with a structure similar to estrogen. They have also been shown to help reduce the negative effects of menopause. Isoflavones are a particular type of phytoestrogens that are found in soy plants and may act like estrogen in providing possible protection against bone loss. This study will compare the effects of isoflavones (including genistein, a type of isoflavone) versus Actonel on calcium absorption and bone loss in post-menopausal women. Participants in this double-blind cross-over study will first complete a screening process, which will include answering questions about their health habits, medical history, physical activity, and food patterns. They will then eat one soy bar daily for 3 days. On Day 4, a urine sample will be taken to assess their ability to metabolize phytoestrogen from soybeans. Participants will be randomly assigned to a specific treatment order. Participants will receive 1-4 unique soy isoflavones, followed by Actonel. Treatment phases will be separated by a 50-day washout period. All participants will also take calcium and vitamin D supplements throughout the study. Assessments will include bone density measurements, calcium absorption tests, and blood and urine tests. The study will last approximately 2.5 years.

Healthy post menopausal women who have been dosed with Ca41. Intervention, 100 mg Gensitein from soy protein isolate for 50 days. After a 50 day washout risedronate (Actonel- 5mg per day) for 50 days

Healthy post menopausal women will consume 5 products containing varying quantities of genistein from different sources for 50 days each in a randomized order. Each intervention period is separated by a 50 day washout period. Intervention: A) 50 mg genistein from soy protein isolate, B) 100 mg genistein from soy protein isolate, C)50 mg genistein from Novasoy, D) 100 mg genistein from Novasoy, E) 100 ng genistein from 50% Novasoy and 50% soy protein isolate

Inclusion Criteria: At least 4 years post-menopausal Exclusion Criteria: Not currently taking estrogen replacement therapy or undergoing any treatment for osteoporosis Diagnosis of breast cancer Results of mammogram suggesting breast cancer

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