Efficacy of Dietary Sodium Restriction of Improving Vascular Endothelial Function in Middle Aged and Older Adults
The investigators hypothesize that reducing salt in the diet will improve the function of blood vessels in middle aged and older adults with moderately elevated systolic blood pressure, by increasing the amount of BH4 and nitric oxide in your blood vessels and reducing the amount of oxidative stress.
|Study Design:||Allocation: Randomized
Endpoint Classification: Efficacy Study
Intervention Model: Crossover Assignment
Masking: Double Blind (Subject, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
|Official Title:||Efficacy of Dietary Sodium Restriction of Improving Vascular Endothelial Function in Middle Aged and Older Adults|
- Improved Flow Mediated Dilation [ Time Frame: Week 5 (after first condition of low salt or normal salt), Week 10 (after second condition, opposite to first) ] [ Designated as safety issue: No ]FMD is analyzed at weeks 5 and 10 or after each condition in this cross-over study design. Subjects are randomly assigned to a low salt or normal salt condition for the first set of 5 weeks and then crossed over to the other condition for the second set of 5 weeks.
- Vascular Oxidative Stress [ Time Frame: Week 5 and Week 10 ] [ Designated as safety issue: No ]Change in FMD following acute infusion of ascorbic acid (a dose known to scavenge superoxide) is measured at the end of 5 weeks of sodium condition (low and normal intake) as an index of vascular oxidative.
|Study Start Date:||February 2009|
|Study Completion Date:||January 2012|
|Primary Completion Date:||January 2012 (Final data collection date for primary outcome measure)|
Subjects on a 1200 mg sodium diet are given 2300 mg sodium in the form of slow sodium tablets to bring them back up to a normal salt intake. Subjects then cross-over to the low sodium condition in the second half of the study.
Drug: Slow sodium tablets
The normal salt condition is maintained with 2300 mg / day in the form of slowly released salt (NaCl) tablets.
Subjects on a 1200 mg salt diet are given placebo pills in order to maintain them on a low salt diet. Subjects then cross-over to the normal sodium condition in the second half of the study.
Placebo tablets are administered to maintain the low sodium condition.
The improvement in blood vessel function will be determined over a 10 week period. Subjects will be randomly assigned to either a 'low salt' condition (placebo pills + 1200 mg dietary sodium) or a 'normal salt' condition (2300 mg sodium chloride pills + 1200 mg dietary sodium) and monitored for 5 weeks. After the initial set of 5 weeks, the subjects are switched into the opposite condition, completing the cross-over study design. During weeks 1-4 and 6-9, subjects are monitored weekly with 24 hour urine collections and diet logs. The assessment of the primary outcome (blood vessel function) is completed during weeks 5 and 10. BH4 and ascorbic acid are also administered during weeks 5 and 10 to measure the effects of sodium intake on endogenous BH4 levels and vascular oxidative stress.
Please refer to this study by its ClinicalTrials.gov identifier: NCT01566084
|United States, Colorado|
|Clinical Translational Research Center|
|Boulder, Colorado, United States, 80309|
|Principal Investigator:||Kristen L Jablonski, PhD||University of Colorado, Boulder|