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

This study has been completed.
Information provided by (Responsible Party):
Douglas Seals, University of Colorado, Boulder
ClinicalTrials.gov Identifier:
First received: March 23, 2012
Last updated: June 21, 2013
Last verified: June 2013

The investigators hypothesize that reducing salt in your diet will improve the function of your blood vessels, by increasing the amount of BH4 and nitric oxide in your blood vessels and reducing the amount of free radicals.

Condition Intervention
Drug: Sodium Chloride Tablets and Tetrahydrobiopterin (BH4)
Drug: 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 1 (screening), Week 5 (after first condition of low salt or normal salt), Week 10 (after second condition, opposite to first) ] [ Designated as safety issue: No ]
    Flow mediated dilation (FMD) is assessed prior to entering the study. If they pass the inclusion requirements, 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:
  • Decreased oxidative stress [ Time Frame: Week 5 and Week 10 ] [ Designated as safety issue: No ]
    Similar to the FMD measurements, oxidative stress is assessed after each condition (low salt and normal salt) which falls during weeks 5 and 10.

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
Placebo Comparator: Salt pill
Subjects on a 1200 mg sodium diet are given 2300 mg sodium in the form of a salt pill to bring them back up to a normal salt intake.
Drug: Sodium Chloride Tablets and Tetrahydrobiopterin (BH4)

The normal salt condition is maintained with 2300 mg / day in the form of slowly released salt (NaCl) pills. This is administered through 10 pills a day.

The BH4 is administered as 10 mg/kg body weight of BH4 on experimental days only.

Experimental: Placebo
Subjects on a 1200 mg salt diet are given placebo pills in order to maintain them on a low salt diet. This is then compared after salt is added back into the diet.
Drug: placebo

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 our primary outcome (blood vessel function) is completed during weeks 5 and 10. BH4 is also administered during weeks 5 and 10 to see the effects of sodium intake on endogenous BH4 levels.


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
  Contacts and Locations
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
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
Study First Received: March 23, 2012
Last Updated: June 21, 2013
Health Authority: United States: Food and Drug Administration

Additional relevant MeSH terms:
Vascular Diseases
Cardiovascular Diseases

ClinicalTrials.gov processed this record on April 16, 2014