Effect of Soy Bread on Markers of Bone Metabolism and Cardiovascular Disease

A study was designed with two specific aims: (1) to assess the effect of soy bread, compared with wheat bread, on markers of bone metabolism and cardiovascular health, and (2) to evaluate whether soy bread consumption affects the metabolism of phytoestrogens. To answer Aim 1, a double-blind randomized crossover trial was conducted. Individuals with an ability to metabolize a specific isoflavone, daidzein, consumed 3 slices of bread (either soy or wheat) daily over a 12-week period. After a 4-week wash-out period, subjects consumed 3 slices/day of the other type of bread. Markers of bone metabolism and cardiovascular health were evaluated before and after each time period. To answer Aim 2, individuals who did not metabolize daidzein at baseline entered a double-blind randomized trial of soy bread with or without fructooligosaccharide (a type of dietary fiber) over an 8-week period. Subjects were evaluated regarding their ability to metabolize daidzein to equol.

Study Overview

• Status: Completed
• Conditions: Cardiovascular Diseases; Osteoporosis
• Intervention / Treatment: Behavioral: Soy bread

Detailed Description

Soy beans are rich in isoflavones, such as genistein and daidzein, which exhibit estrogenic activity. While the cardiovascular benefits of isoflavones in soy have been recognized, the effects on bone metabolism are less well known. The National Aeronautics and Space Administration expressed an interest in the effects of soy on bone loss and a former NASA scientist developed a soy product, soy bread, which may be more palatable for most Americans than currently available soy foods. A two-treatment two-period crossover trial was conducted to assess the effects of soy bread consumption on deoxypyridinoline, N-telopeptides, bone-specific alkaline phosphatase, osteocalcin, calcium, leptin, insulin-like growth factor-1, luteinizing hormone, follicle-stimulating hormone, testosterone, cholesterol (total, HDL, LDL), triglycerides, apolipoprotein AI, apolipoprotein B, C-reactive protein, and glycosylated hemoglobin. The crossover trial was conducted in subjects identified as having the ability to metabolize daidzein to equol. The treatment was 3 servings of soy bread daily over a 12-week period. The control period included 3 servings of a placebo wheat bread over a 12-week period. For subjects who did not metabolize daidzein to equol at baseline, a pretest-posttest trial of soy bread consumption over an 8-week period was conducted to examine whether 3 servings/day of soy bread increased urinary equol concentrations and whether the addition of fructooligosaccharide enhanced this excretion.

• Study Type: Interventional
• Enrollment (Actual): 18
• Phase: Phase 1

Contacts and Locations

Study Locations

• United States
  • Michigan
    • Ann Arbor, Michigan, United States, 48109
      • University of Michigan

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 50 years and older (Adult, Older Adult)
• Accepts Healthy Volunteers: Yes
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Post-menopausal women and men who were 50 years of age or older.

Exclusion Criteria:

• Allergy to soy, wheat, and/or nuts. Use of hormone replacement therapy within the past 6 months. Diagnosis of osteoporosis or use of bone loss medications. Use of drugs within the past 3 months which increase the risk of osteoporosis. End-stage renal disease or other nephropathies. Chemotherapy within the past 6 months. Active gastrointestinal disorders. Diagnosis of thyroid disorder. Use of cholesterol-lowering medications within the past month. Vitamin, mineral, protein, and/or calorie deficiency. Alcoholism, acute or chronic hepatitis, cirrhosis. Use of systemic antibiotics within the past 6 months. Currently under dietary restrictions that would conflict with the intervention. Anticipated mental or physical incapability of adhering to the dietary protocol during the time period of the study (e.g. expected travel).

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Randomized
• Interventional Model: Crossover Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Experimental: Soy bread; Soy bread (75-100 mg isoflavone/day) for 12 weeks	Behavioral: Soy bread
Active Comparator: Wheat bread; Wheat bread for 12 weeks	Behavioral: Soy bread

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
deoxypyridinoline	Urinary deoxypyridinoline	12 weeks

Secondary Outcome Measures

Outcome Measure	Time Frame
N-telopeptides, bone-specific alkaline phosphatase, osteocalcin, cholesterol, triglycerides, apolipoproteins, C-reactive protein, HbA1c	12 weeks

Collaborators and Investigators

• Sponsor: University of Michigan
• Collaborators: Ohio State University
• Investigators: Principal Investigator: Mary A.M. Rogers, PhD, University of Michigan

Study record dates

Study Major Dates

• Study Start: January 1, 2004
• Primary Completion (Actual): May 1, 2008
• Study Completion (Actual): May 1, 2008

Study Registration Dates

• First Submitted: August 17, 2006
• First Submitted That Met QC Criteria: August 17, 2006
• First Posted (Estimate): August 21, 2006

Study Record Updates

• Last Update Posted (Estimate): December 2, 2014
• Last Update Submitted That Met QC Criteria: December 1, 2014
• Last Verified: December 1, 2014

More Information

Terms related to this study

• Keywords: diet; isoflavones; hyperlipidemia; soy; bone resorption; osteogenesis
• Additional Relevant MeSH Terms: Metabolic Diseases; Musculoskeletal Diseases; Bone Diseases; Bone Diseases, Metabolic; Cardiovascular Diseases; Osteoporosis
• Other Study ID Numbers: GCRC Protocol #1971