Effectiveness of Vitamin D Supplementation on Reducing Blood Pressure and Improving Endothelial Function of Pre-menopausal African American Women
Trial Snapshot
- Phase
- Not Applicable
- Status
- Terminated
- Sponsor
- Texas Woman's University
- Enrollment
- 27
- Locations
- 2
- Primary Endpoint
- Effectiveness of Vitamin D Supplementation on Reducing Blood Pressure
Study Overview
Brief Summary
This pilot study will examine the effectiveness of vitamin D supplementation on reducing blood pressure and improving endothelial function. Premenopausal African American women will be recruited. Participants will be instructed to record food intake for three days to estimate usual dietary intake at baseline and at the 10th week. At the baseline clinic visit a 10 week supply of vitamin D3 supplements (2,000 IU/day; Nature Made ®) will be given to participants and log sheets provided to record supplement intake. To answer the primary research questions, within subjects repeated measures analysis of variance (ANOVA) tests will be conducted to test if any differences in blood pressure, serum 25(OH)D concentrations, and RHI are statistically different after 10 weeks of supplementation with 2,000 IU/d of vitamin D. Exploratory multivariate linear regression models will be constructed to determine relationships between vitamin D status and vascular function parameters (blood pressure, RHI) before and after adjustment for age and BMI.
Detailed Description
This pilot study will examine the effectiveness of vitamin D supplementation on reducing blood pressure and improving endothelial function. If results of the pilot study are favorable, findings will be used to design a possibly larger study to confirm results. Premenopausal African American women (n = 40) will be recruited. All participant study visits will be held at the Houston Methodist Internal Medicine Clinic or at the TWU Nutrition Laboratory. African American women will be recruited who are not taking hypertensive medications, have average blood pressure measurements < 140/90 mmHg, are not pregnant or planning on becoming pregnant in the next three months, or who are not lactating.
Enrollment Visit The day prior to the enrollment visit potential subjects will fast overnight and refrain from consuming any caffeinated products, vitamins, or medications that may affect vascular tone and refrain from smoking. the investigators will explain the 10 week study design and obtain participant consent. Testing will be performed in the morning with start times between 8 and 10:00 a.m. In a quiet and temperature-controlled room (72° to 75° F), initial systolic and diastolic blood pressure measurements following 5 minutes of seated rest following the American Heart Association Blood Pressure Guidelines. The arm will be supported at heart level and neither participant nor observer will talk during the measurements. Three successive measurements will be collected with an automated oscillometric sphygmomanometer and the average of the last two measurements will be calculated. Any individual with an average blood pressure > 140/90 mmHg will be referred to their personal physician for follow up.
Consented participants with blood pressure readings <140/90 mmHg will be instructed to consume their usual diet for the next week and to complete a three-day diet record of two week days and one weekend. Instructions on how to record the dietary diary will be given. Food records will be used to estimate usual dietary intake for the baseline and 10 week time points. An appointment will be scheduled for the participant to return with completed food records to begin the intervention study. At the baseline clinic visit a 10 week supply of vitamin D3 supplements (2,000 IU/day; all the same lot; Nature Made ®) will be given to participants and log sheets provided to record supplement intake. In addition, participants will be instructed to avoid traveling to sunny locations for 10 weeks.
Baseline and 10 week clinic visits
Nutrient intake:
Study Design
- Study Type
- Interventional
- Allocation
- Na
- Intervention Model
- Single Group
- Primary Purpose
- Prevention
- Masking
- None
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- Female
- Accepts Healthy Volunteers
- Yes
Inclusion Criteria
- •Healthy pre-menomausal African American women
Exclusion Criteria
- •History of elevated blood pressure >140/90 mm Hg
- •Pregnant or planning to become pregnant in the next three months
- •Lactating
- •Known Crohn's
- •Inflammatory bowel disease
- •Previous bowel resections
- •Bariatric surgeries, or psoriasis
- •Artificial or long fingernails they do not want to cut for testing
- •Regularly taking medications that might affect endothelial function such as anti-inflammatory medications, statins, anti-hypertensive medication, daily aspirin, non-SSRI psychotropic medication, and dietary supplements including vitamin D supplements
Arms & Interventions
Intervention
2,000 IU of vitamin D given to African American women for 10 weeks
Intervention: 2,000 International Units (IU)of vitamin D3 (Dietary Supplement)
Outcomes
Primary Outcomes
Effectiveness of Vitamin D Supplementation on Reducing Blood Pressure
Time Frame: Baseline and 10 weeks
Changes in systolic and diastolic blood pressure will be measured at baseline and following vitamin D supplementation for 10 weeks in African American healthy pre-menopausal women
Secondary Outcomes
- Effectiveness of Vitamin d Supplementation on Improving Endothelial Function(Baseline and 10 weeks)
Investigators
Carolyn Moore
Associate Professor
Texas Woman's University