Contact information
Type
Scientific
Primary contact
Dr Andrea Hutchins
ORCID ID
Contact details
Department of Nutrition
Arizona State University
7001 East Williams Field Road
Mesa
85212
United States of America
+1 480 727 1097
andrea.hutchins@asu.edu
Additional identifiers
EudraCT number
ClinicalTrials.gov number
Protocol/serial number
N/A
Study information
Scientific title
Effect of soy isoflavones and ascorbic acid supplementation on antioxidant activity in postmenopausal women: a randomised controlled trial
Acronym
Study hypothesis
This study investigated the extent to which vitamin C and isoflavones, as single or combined supplements to a habitual diet, provided antioxidant effects by reducing lipid oxidation in blood. Healthy, non-smoking, postmenopausal women were screened for regular soy consumption (one serving per day), vitamin C supplementation (60 mg/day), and postmenopausal status.
Utilising a randomised, double blind, crossover design, ten subjects were assigned to one of four dietary treatments. Subjects were instructed to continue their habitual physical activity and dietary habits during the 14-week experiment. The subjects completed consecutive two-day diet and activity logs immediately prior to each fasted blood draw. Diet and activity logs were analysed. Fasting blood was collected in vacuutainers, centrifuged, and plasma aliquots were frozen at -70°C for later analysis.
Plasma vitamin C concentration was determined using a 2,4-dinitrophenylhydrazine method by Omaye. Lipid peroxides were measured using the flurometric method. Total cholesterol was determined by a photometric assay; high-density lipoprotein (HDL) cholesterol by a homogenous enzyme immunoassay; and, triglycerides and low-density lipoprotein (LDL) cholesterol by a colorimetric assay (performed by Sonora Quest Laboratories, Phoenix, AZ).
Ethics approval
The Human Subjects Committee of the Institutional Review Board of Arizona State University approved this study; all participants gave written informed consent before participating.
Study design
Randomised, double blind, crossover designed study
Primary study design
Interventional
Secondary study design
Randomised controlled trial
Trial setting
Not specified
Trial type
Treatment
Patient information sheet
Condition
Antioxidant markers and risk factors for heart disease
Intervention
Ten subjects were assigned to one of four dietary treatments:
1. Supplement of 5 mg isoflavones per kg/body weight (IF)
2. 500 mg vitamin C supplement (VC)
3. Supplement of 5 mg isoflavones per kg/body weight and 500 mg vitamin C supplement (IF-VC)
4. Placebo (C)
The two week treatment periods were separated by a two week washout period.
Intervention type
Supplement
Phase
Not Specified
Drug names
Vitamin C and isoflavones
Primary outcome measure
Lipid peroxides
Secondary outcome measures
1. Vitamin C
2. Total cholesterol, including LDL, HDL and Triglycerides (TG)
3. Blood pressure
Overall trial start date
01/01/2002
Overall trial end date
30/06/2002
Reason abandoned (if study stopped)
Eligibility
Participant inclusion criteria
Healthy, nonsmoking, postmenopausal women were screened for regular soy consumption (less than or equal to one serving per day), vitamin C supplementation (less than or equal to 60 mg/day), and postmenopausal status (one year).
Participant type
Patient
Age group
Adult
Gender
Female
Target number of participants
10
Participant exclusion criteria
1. Vegetarianism
2. Current or past diagnosis of cancer
3. Cardiovascular disease or diabetes
4. Chronic illness or inflammation
5. Gastrointestinal disorders
6. Recent (previous six months) use of antibiotics, and use of hypoglycaemic or hypolipidaemic medication
7. Body mass index (BMI) less than or equal to 35 kg/m^2
8. Consumed less than or equal to two alcoholic drinks per day
Recruitment start date
01/01/2002
Recruitment end date
30/06/2002
Locations
Countries of recruitment
United States of America
Trial participating centre
Department of Nutrition
Mesa
85212
United States of America
Sponsor information
Organisation
Arizona State University - Sustainable Technologies, Agribusiness and Resource Center (USA)
Sponsor details
c/o John Brock
Center Coordinator
7001 East Williams Field Road
Arizona State University
Mesa
85212
United States of America
-
john.brock@asu.edu
Sponsor type
University/education
Website
Funders
Funder type
University/education
Funder name
Arizona State University - Sustainable Technologies, Agribusiness and Resource Center (USA)
Alternative name(s)
Funding Body Type
Funding Body Subtype
Location
Results and Publications
Publication and dissemination plan
Not provided at time of registration
Intention to publish date
Participant level data
Not provided at time of registration
Basic results (scientific)
Publication list
1. 2005 case report in: https://www.ncbi.nlm.nih.gov/pubmed/15975148
2. 2005 results in: https://www.ncbi.nlm.nih.gov/pubmed/15983534
Publication citations
-
Case report
Hutchins AM, McIver IE, Johnston CS, Hypertensive crisis associated with high dose soy isoflavone supplementation in a post-menopausal woman: a case report [ISRCTN98074661]., BMC Womens Health, 2005, 5, 9, doi: 10.1186/1472-6874-5-9.