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

University of Colorado Boulder (CU)

Status: Completed

Conditions: Hypertension

Treatments: Other: placebo; Drug: Slow sodium tablets

Study type: Interventional

Funder types: Other; NIH

Identifiers

NCT01566084

B5114

F31AG033994 (U.S. NIH Grant/Contract)

Details and patient eligibility

About

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.

Full 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.

Enrollment: 17 patients

Sex: All

Ages: 50 to 79 years old

Volunteers: Accepts Healthy Volunteers

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

Trial design

Primary purpose: Treatment

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Triple Blind

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17 participants in 2 patient groups

Normal sodium

Other group

Description:

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.

Treatment:

Drug: Slow sodium tablets

Low sodium

Other group

Description:

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.

Treatment:

Other: placebo