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OpenTrials
Completed

NCT Number: NCT01566084

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.

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Key information

Conditions

Hypertension Cardiovascular Diseases Vascular Diseases

Age range

50 year–79 year

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Primary location

Clinical Translational Research Center

Boulder, Colorado, 80309, United States

About this study

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.

Who can participate

Healthy volunteers accepted: Yes

Only the study team can determine whether someone qualifies for participation.

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

Treatment and study plan

Slow sodium tablets

Drug

The normal salt condition is maintained with 2300 mg / day in the form of slowly released salt (NaCl) tablets.

Placebo

Other

Placebo tablets are administered to maintain the low sodium condition.

Primary outcomes

  1. 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)

    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 outcomes

  1. Vascular Oxidative Stress

    Time frame: Immediately following acute infusion of ascorbic acid on Weeks 5 and 10

    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.

  2. BH4 Bioavailability

    Time frame: Immediately following acute administration of BH4 on Weeks 5 and 10

    Change in FMD following acute oral tetrahydrobiopterin (BH4) is measured at the end of 5 weeks of sodium condition (low and normal intake) as an index of BH4 bioavailability.

Sponsors and collaborators

Lead sponsor

University of Colorado, Boulder

Other

Collaborators

  • National Institute on Aging (NIA)

Registry information

Important dates

Study start
2009
Primary completion
2012
Study completion
2012
First posted
Mar 29, 2012
Registry last updated
Jan 7, 2016

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

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