Safety and Effectiveness of Soy Phytoestrogens to Prevent Bone Loss

Safety, Efficacy, and Optimal Dosage of Soy Isoflavones to Prevent Osteoporosis

Status

Completed

Phases

Study type

Interventional

Source

ClinicalTrials.gov

Registry ID

NCT00665860

Acronym

OPUS

Enrollment

403

Registered

2008-04-24

Start date

2001-04-30

Completion date

2006-06-30

Last updated

2020-11-27

For informational purposes only — not medical advice. Sourced from public registries and may not reflect the latest updates. Terms

Conditions

Osteoporosis

Keywords

Osteoporosis, Soy isoflavones, Postmenopausal women, Safety, Efficacy, Effective dosage

Brief summary

The purpose of this study is to determine whether soy isoflavone supplementation is safe and effective to prevent bone loss in postmenopausal women.

Detailed description

Over-the-counter soy isoflavone supplement usage is becoming common among postmenopausal women. However, there is no documented scientific evidence of its long-term safety and efficacy in preventing osteoporosis. Our primary goal is to determine the safety, efficacy, and optimal dosage of isoflavone supplementation to reduce bone loss in postmenopausal women. The multi-state, multi-institutional design ensures that the study results are representative of postmenopausal women in the U.S. population. Confirming the skeletal benefits of soy isoflavones could translate into reduced healthcare costs related to osteoporosis.

Interventions

DIETARY_SUPPLEMENTPlacebo

Three pills per day for two years

DIETARY_SUPPLEMENTSoy isoflavones

Three pills that delivered 80 mg of aglycone isoflavones per day for two years

Study design

Allocation

RANDOMIZED

Intervention model

FACTORIAL

Primary purpose

PREVENTION

Masking

TRIPLE (Subject, Investigator, Outcomes Assessor)

Eligibility

Sex/Gender

FEMALE

Age

40 Years to 60 Years

Healthy volunteers

Yes

Inclusion criteria

* Must be able to swallow the pills * No menses for 12 months * Blood follicle stimulating hormone great than 30 IU/mL * Lumbar spine bone mineral density t-score equal to or greater than -1.5

Exclusion criteria

* Strict vegetarians * Current or recent smokers (within last five years) * Abnormal screening mammogram, Pap smear and blood chemistries * Clinical diagnosis of osteoporosis, spine and/or hip fracture, cancer, liver, kidney, gallbladder and heart disease * Clinical diagnosis of psychiatric disorder * Any allergic reactions to soy products * Current treatment with bisphosphonates, calcitonin, fluoride, corticosteroids, tamoxifen, raloxifene, HRT, premarin, farestron and letrozole * Current usage of black cohosh, blue cohosh, dong quai, Caltrate 600+Soy, Estroven, ginseng, Healthy Women, Natural Estrogen, Opti-Soy, PhytoFem, Probalance, Promensil, Remifemin, Rimostil and Trinovin

Design outcomes

Primary

Measure	Time frame
Bone mineral density	One year and two years

Secondary

Measure	Time frame
Blood biochemical bone markers (osteocalcin, bone-specific alkaline phosphatase, cross-linked N-telopeptides of type 1 collagen)	One year and two years

Countries

United States

Outcome results

None listed

Source: ClinicalTrials.gov · Data processed: Apr 2, 2026