NCT00668447

Soy and Isoflavones Effect on Bone

Soy Proteins and Isoflavones Impact Bone Mineral Density in Older Women

• Status: Completed
• Phase: Phase 4
• Study type: Interventional
• Enrollment: 97 (actual)
• Sponsor: United States Department of Agriculture (USDA) · Federal
• Sex: Female
• Age: 65 Years
• Healthy volunteers: Accepted

Summary

The purpose of this study is to test the effect of 1 year of added dietary soy protein and/or soy isoflavones on bone mineral density in late postmenopausal women.

Detailed description

Although soy foods contain several components (isoflavones and amino acids) that could potentially have positive effects on bone health, there are few long term, large, clinical trials using soy as a means of improving bone mineral density. The objective of this study is to provide daily soy protein and isoflavones to healthy older women in order to answer three major questions: 1. Does soy protein alone affect bone metabolism? 2. Do isoflavones, given with soy protein, affect bone metabolism? 3. What dose of isoflavones affects bone in older women? We hypothesize that soy protein will have a beneficial effect on bone in older women compared to control protein. Further, we hypothesize that there will be an additional benefit to bone in women who receive soy protein plus isoflavones (at both doses) compared to soy protein alone. Both control and soy proteins used in the study were isolates, meaning they were the highest concentration of protein (85-90% by weight) in order to minimize the volume of protein supplement that each woman was asked to ingest on a daily basis. The soy protein was an alcohol-washed, soy protein isolate containing 90% protein and negligible isoflavone (0.2 mg/g product). The control protein was a mix consisting of 50% protein from sodium caseinate, 25% protein from whey protein and 25% from egg white protein. The use of a mix of proteins as a control provides a more balanced level of amino acids, mimics the real life mix of proteins that humans typically consume, and avoids the unique characteristics of one source of protein. In order to maintain the dietary protein intake constant, the participant was counseled to decrease her intake of other sources of protein from primarily animal sources by approximately 3 ounces per day (the approximate equivalent of the protein powders). The isoflavones tablets each contained 57 mg of total isoflavone from primarily genistein, glycitein, and daidzein and their beta-glycosides.

Conditions

• Osteoporosis

Interventions

Type	Name	Description
DIETARY_SUPPLEMENT	Soy Isolate	20 grams of powder mixed in beverages or food daily for one year
DIETARY_SUPPLEMENT	Control protein	20 grams of powder mixed in beverages or food daily for one year
DIETARY_SUPPLEMENT	Novasoy isoflavones	3 tablets daily for one year
DIETARY_SUPPLEMENT	Placebo tablets	3 tablets daily for one year

Timeline

• Start date: 2001-11-01
• Primary completion: 2005-06-01
• Completion: 2005-06-01
• First posted: 2008-04-29
• Last updated: 2008-04-29

Locations

1 site across 1 country: United States