Efficacy of Dietary Sodium Restriction of Improving Vascular Endothelial Function in Middle Aged and Older Adults

This study has been completed.
National Institute on Aging (NIA)
Information provided by (Responsible Party):
Douglas Seals, University of Colorado, Boulder
ClinicalTrials.gov Identifier:
First received: March 23, 2012
Last updated: May 20, 2014
Last verified: May 2014
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.

Condition Intervention
Drug: Slow sodium tablets
Other: placebo

Study Type: Interventional
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

Resource links provided by NLM:

Further study details as provided by University of Colorado, Boulder:

Primary Outcome Measures:
  • 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.

Secondary Outcome Measures:
  • 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.

Enrollment: 17
Study Start Date: February 2009
Study Completion Date: January 2012
Primary Completion Date: January 2012 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Normal sodium
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.
Low sodium
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.
Other: placebo
Placebo tablets are administered to maintain the low sodium condition.

Detailed Description:
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.

Ages Eligible for Study:   50 Years to 79 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • 50-79 years of age
  • SBP 130-159 mmHg

Exclusion Criteria:

  • Have been sick with an infection in the past two weeks
  • Are currently sick or have ongoing health problems such as kidney or CVD
  • Have lost more than 11 lbs. in the last 3 months
  • Are taking any type of antioxidants
  • Smoke or have alcohol problems
  • Have blood glucose levels higher than 126 mg/dL
  • Have resting SBP below or less than 100 mmHg or greater than 159 mmHg
  • Have a resting diastolic blood pressure greater than 99 mmHg
  • Have a BMI greater than 40 kg/m^2
  • Are presently consuming less than 9 or greater than 18 grams of salt / day
  • Have a baseline FMD of greater than 6%
  • Are taking any of the following types of drugs: blood thinners, anti-seizure medications, ant-inflammatory drugs
  • Participate in any high endurance athletic training
  • Taking Hormone Replacement Therapy
  • Have not been post-menopausal for at least 1 year
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Please refer to this study by its ClinicalTrials.gov identifier: NCT01566084

United States, Colorado
Clinical Translational Research Center
Boulder, Colorado, United States, 80309
Sponsors and Collaborators
University of Colorado, Boulder
National Institute on Aging (NIA)
Principal Investigator: Kristen L Jablonski, PhD University of Colorado, Boulder
  More Information

Additional Information:
No publications provided

Responsible Party: Douglas Seals, College Professor of Distinction, University of Colorado, Boulder
ClinicalTrials.gov Identifier: NCT01566084     History of Changes
Other Study ID Numbers: B5114, F31AG033994
Study First Received: March 23, 2012
Results First Received: May 20, 2014
Last Updated: May 20, 2014
Health Authority: United States: Food and Drug Administration

ClinicalTrials.gov processed this record on November 27, 2015