Bone Response to Soy Isoflavones in Women

Osteoporosis Clinical Trial

— SIRBL  

Official title:

Bone Response to Soy Isoflavones in Women

Clinical Trial Details — Status: Completed

Administrative data

• NCT number: NCT00043745
• Other study ID #: R01AR046922
• Secondary ID: R01AR046922NIAMS
• Status: Completed
• Phase: Phase 2
• First received: August 13, 2002
• Last updated: February 6, 2013
• Start date: March 2003

Study information

• Verified date: February 2013
• Source: Iowa State University
• Contact: n/a
• Is FDA regulated: No
• Health authority: United States: Federal Government
• Study type: Interventional

Clinical Trial Summary

This study will provide valuable data on whether soy isoflavones impact bone loss in postmenopausal women. The study will help clarify potential mechanisms and contribute to our understanding of isoflavones as an alternative to traditional hormone therapy.

Description:

Soy protein, rich in isoflavones (estrogen-like compounds), has been shown to prevent bone loss in ovariectomized rats. Short-term preliminary study results in perimenopausal women suggest a bone-sparing effect. Great interest in isoflavones as an alternative to hormone replacement therapy has emerged, yet the long-term efficacy of isoflavones on bone in humans is unknown. Our objective is to determine the three-year efficacy of isoflavone-rich soy extract in attenuating bone loss in postmenopausal women. The central hypothesis is that soy isoflavones will attenuate bone loss in these women by maintaining bone formation, which is modulated by growth factors and isoflavone metabolism. The rationale for this research is that current hormone therapy is fraught with adverse side effects, resulting in non-compliance. This randomized, double-blind, placebo-controlled clinical trial will examine the effects of two doses (80 or 120 mg daily) of isoflavone-rich soy extract on bone in non-osteoporotic postmenopausal women (N=234). The specific aims of this study are: 1) to determine the bone-preserving effects of isoflavones on lumbar spine bone mineral density (BMD); 2) to relate treatment-induced changes in BMD to changes in biochemical markers of bone turnover; 3) to identify potential mechanisms by which isoflavones prevent or modulate bone loss by measuring endogenous estrogens, sex hormone-binding globulin, insulin-like growth factor-I (IGF-I), urinary minerals, serum 25(OH)vitamin D, plasma isoflavones and their metabolites, and customary intake of isoflavone-containing soy; and, 4) to ascertain the safety of isoflavone-rich soy extract. Postmenopausal women will be recruited at two sites (117 at Iowa, 117 at California). Random effects repeated measures analyses will be used to characterize change in BMD as the primary outcome, estimate treatment-induced effects, and depict change in markers of bone turnover in relation to BMD change. We will use intent-to-treat for the primary test, but also account for potential modulators (reproductive hormones, IGF-I, plasma isoflavones) that affect bone, as indicated in specific aim 3.

Recruitment information / eligibility

• Status: Completed
• Enrollment: 224
• Est. primary completion date: April 2008
• Accepts healthy volunteers: Accepts Healthy Volunteers
• Gender: Female
• Age group: 45 Years to 65 Years

Eligibility

Inclusion Criteria:

• Early postmenopausal (i.e., no menses during past 12 months) women, with an upper limit of 10 years since their last cycle

• Natural menopause (i.e., no hysterectomies or oophorectomies)

• Body mass index (BMI) > 20 and < 30

Exclusion Criteria:

• Current or previous (within 12 months) use of hormone replacement therapy, hormonal contraceptives, estrogens, or progestogens

• Current use of pharmacologic agents, such as selective estrogen-receptor modulators (SERMs) (e.g., raloxifene or tamoxifen) or anti-resorptive agents (e.g., alendronate or calcitonin), herbal therapies that may have estrogenic effects (e.g., herbimycin, tryphostins), or cigarettes

• Strict vegans (but will include lacto-ovo-, lacto-, and ovo-vegetarians)

• Metabolic bone disease, renal disease, history of urolithiasis, cancer, cardiovascular disease, diabetes mellitus, respiratory disease, gastrointestinal disease, liver disease, or other chronic diseases

• First-degree relative with breast cancer

• Lumbar spine BMD >= -1.5 standard deviations (SD) below mean (high-risk for osteoporosis) and BMD >= +1.0 SD above mean

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Double Blind (Subject, Investigator, Outcomes Assessor), Primary Purpose: Prevention

Related Conditions & MeSH terms

• Osteopenia
• Osteoporosis

Intervention

Dietary Supplement:
• Soy isoflavones
Soy isoflavones extracted from soy protein, compressed into tablets; three tablets taken daily
• Extract tablets
Extract from soy protein, but devoid of isoflavones; three tablets taken once daily

Locations

Country	Name	City	State
United States	Iowa State University	Ames	Iowa
United States	USDA/ARS/WHNRC University of California-Davis	Davis	California

Sponsors (2)

Lead Sponsor	Collaborator
Iowa State University	National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS)

Country where clinical trial is conducted

United States, 

Outcome

Type	Measure	Description	Time frame	Safety issue
Primary	Lumbar spine bone mineral density		Year 3	Yes
Secondary	Proximal femur bone mineral density		Year 3	Yes