Effect of Vitamin D3 on Vascular Function
Vitamin D is a natural nutrient. A little comes from our normal daily diet. Most of it comes from our skin after we have been in sunlight. If we have darker skin, we make less vitamin D. Vitamin D balances the calcium in our body. If our vitamin D levels get too low it can cause health problems. It may increase our chance of getting high blood pressure or diabetes. Another problem we may have if our vitamin D levels are low is that our blood vessels may not work normally. These are important health problems for anyone. Because African Americans have darker skin, they are more likely than most other racial/ethnic groups to have low vitamin D levels. This study will look at treating African Americans with low vitamin D levels.
The goal of this study is to see how vitamin D helps blood vessels work. The investigators will do this study in African Americans who are overweight, have high blood pressure and have low vitamin D levels. The investigators will see if getting the vitamin D level to a normal value will improve how blood vessels work. The dose of vitamin D that will be given in this study is a high dose that is given to people with low vitamin D levels.
|Study Design:||Allocation: Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Single Group Assignment
Masking: Double Blind (Subject, Investigator)
Primary Purpose: Prevention
|Official Title:||The Effect of Cholecalciferol (Vitamin D3) on Vascular Function and Cardiovascular Risk Factors|
- The primary outcome variable is pulse wave velocity for vascular stiffness assessed by radial artery tonometry (via SphygmoCor). The hypothesis is that a greater decrease in the PWV will occur with the Vitamin D3 treatment. [ Time Frame: one year ] [ Designated as safety issue: No ]
- Improved vascular/endothelial function as determined by measuring non-invasive vascular finger plethysmography (via EndoPat),sitting and 24 hour ambulatory blood pressure. [ Time Frame: one year ] [ Designated as safety issue: No ]
|Study Start Date:||July 2009|
|Estimated Study Completion Date:||April 2012|
|Primary Completion Date:||July 2011 (Final data collection date for primary outcome measure)|
Experimental: placebo and vitamin D
Subjects with low vitamin D levels, diabetes and hypertension
Drug: vitamin D
Two 50,000 IU tablets of oral Vitamin D3 will be given every 4 weeks.Drug: Placebo
Two tablets of oral placebo (microcrystalline cellulose),matching in appearance to the Vitamin D3, will be given every 4 weeks.
Cardiovascular Disease (CVD) and related disorders remain the leading cause of death in the nation. Hypovitaminosis D has been linked not only to several cardiovascular (CV) risk factors including hypertension, diabetes, obesity but also to increased rates of CVD. Thus,hypovitaminosis D presents a common pathway for a select subgroup with a clustering of CV risk factors in a profile that is predominant among ethnic minorities. Indeed, hypovitaminosis D is highly prevalent with an estimated 55% of the US adult population having levels at or below 30 ng/ml, and over 80% of African Americans having suboptimal values. Thus, we propose a twelve week randomized double-blind, placebo controlled pilot trial to assess the effect on vascular function and CV risk factors of 100,000 IU Vitamin D3 given every 4 weeks to overweight, hypertensive African-Americans with hypovitaminosis D. To our knowledge, the proposed project is the first to assess the effect of 'high-dose' Vitamin D3 administration on vascular function.We believe this study is also the first to examine the impact at a molecular level of Vitamin D3 repletion on the key mediators of cardio-metabolic pathways in humans. If our study results support our working hypothesis, we will be positioned to propose a larger scale study to detect a therapeutic effect on more definitive, clinical cardiovascular endpoints across a more diverse population.