Timing of Sodium Intake and Nocturnal Sodium Excretion and Blood Pressure in Obese African Americans

NCT04021355 | Completed

• 1 other identifier: IRB-300003394
• Study Type: interventional
• Target: 53
• Locations: 1 country
• Sites: 1

Brief Summary

Experimental data have shown that timing of sodium intake impacts diurnal patterns of sodium excretion. The purpose of this study is to test the hypothesis that the time of day for salt intake impacts (1) blood pressure rhythms and urinary sodium excretion and (2) circadian timing of factors responsible for blood pressure regulation and cardiometabolic health in obese individuals. These studies will address two aims. The first aim will test the hypothesis that limiting high salt intake prior to sleep increases day-night differences in blood pressure, improves timing of urinary sodium excretion, and improves metabolic risk factors. The second aim will test the hypothesis that limiting high salt intake prior to sleep preferentially improves rhythmicity in peripheral vs. central circadian clock factors linked to renal sodium handling. The proposed hypothesis-driven studies will determine how timing of sodium intake affects diurnal blood pressure and circadian timing of factors responsible for blood pressure control and metabolic health, with the ultimate goal of identifying novel strategies to treat nocturnal hypertension and metabolic disease in obesity.

Conditions

Obesity; Hypertension; Circadian Dysregulation; Salt; Excess

Outcome Measures

Primary Outcomes (3)

• 24-hour blood pressure

  Difference in nocturnal blood pressure between study arms

  7 days

• Core Body Temperature

  Difference in core body temperature between study arms

  7 days

• Timing of plasma melatonin increase under dim-light conditions (dim-light melatonin onset)

  Difference in the rise of plasma melatonin during the night under dim-light conditions between study arms

  8 days

Secondary Outcomes (10)

• 24-hour urinary sodium excretion

  8 days

• Buccal cell clock gene expression (CLOCK, Bmal1, per1, per2, Rev-erb-alpha, cry1, cry2)

  8 days

• Concentrations of plasma melatonin

  8 days

• Concentrations of plasma cortisol

  8 days

• Peripheral blood monocyte clock gene (CLOCK, Bmal1, per1, per2, Rev-erb-alpha, cry1, cry2) expression

  8 days

Study Arms (2)

Early Sodium

EXPERIMENTAL

Early sodium load: participants will consume a standardized diet providing 2.3 g of sodium per day for 7 days (run-in period), after which they will continue to consume the standardized diet for 9 days and in addition will take 2 g of sodium in the form of salt tablets with breakfast each day.

Other: Oral sodium supplementation

Late Sodium

EXPERIMENTAL

Late sodium load: participants will consume a standardized diet providing 2.3 g of sodium per day for 7 days (run-in period), after which they will continue to consume the standardized diet for the next 9 days and in addition will take 2 g of sodium with dinner each day.

Other: Oral sodium supplementation

Interventions

Oral sodium supplementation OTHER

Participants will receive dietary sodium supplementation in the form of tablets to be taken either with breakfast or dinner.

Early Sodium; Late Sodium

Eligibility Criteria

• Age: 25 Years - 45 Years
• Sex: all
• Healthy Volunteers: Yes
• Age Groups: Adult (18-64)

You may qualify if:

• obese (BMI 30-50 kg/m2)
• years of age

You may not qualify if:

• evidence of kidney disease (eGFR \< 60 ml/min/1.73m2 or abnormal urinalysis)
• elevated BP (\>150/90 mmHg \[measured at screening in duplicate after 10min lying recumbent\])
• elevated fasting glucose (\>126 g/dL on screening labs)
• severe anemia (hemoglobin \< 8 g/dL for women or \< 9 g/dL for men)
• significant psychiatric illness (as assessed by a validated screening form)
• past or present drug or alcohol abuse (drug screen)
• taking 2 or more BP medications or supplements on a regular basis
• alcohol intake more than 2 drinks/day
• pregnancy
• women taking hormone replacement therapy, or post-menopausal women;
• shift worker
• sleep disorders (such as sleep apnea assessed by Apnea Link)
• major chronic disease (e.g., diabetes, lymphocyte disorders)
• history of smoking or use of tobacco products within the past year
• use of sleep medications, hypnotics, stimulants, or anti-depressants

Sponsors & Collaborators

• University of Alabama at Birmingham: lead

Study Sites (1)

University of Alabama

Birmingham, Alabama, 35294, United States

Location

MeSH Terms

Conditions

Obesity; Hypertension; Chronobiology Disorders

Condition Hierarchy (Ancestors)

Overweight; Overnutrition; Nutrition Disorders; Nutritional and Metabolic Diseases; Body Weight; Signs and Symptoms; Pathological Conditions, Signs and Symptoms; Vascular Diseases; Cardiovascular Diseases; Nervous System Diseases

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: OTHER
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: PRINCIPAL INVESTIGATOR
• PI Title: Principal Investigator

Study Record Dates

• First Submitted: July 11, 2019
• First Posted: July 16, 2019
• Study Start: July 14, 2020
• Primary Completion: June 14, 2025
• Study Completion: July 31, 2025
• Last Updated: December 17, 2025

Record last verified: 2025-12

Locations

US (1)