Potassium, Hydration, Cardiovascular, and Kidney Study (PHACKs) (PHACKs)

The Effects of Water and Potassium Supplementation on Cardiovascular and Kidney Function in Young Adults

Compared with White Adults, Non-Hispanic Black Adults are at an elevated risk of developing cardiovascular disease (CVD) and end stage chronic-kidney disease (CKD), two of the leading causes of death in the United States. Inadequate hydration status is associated with risk factors for both CVD and CKD. Prior data show that Black individuals are less likely to be adequately hydrated when compared with their White counterparts. Further, socioeconomic factors have been shown to influence hydration practices. Inadequate hydration influences certain hormones that regulate blood volume and impact blood pressure, but increasing potassium intake may provide some positive effects on normalizing these hormones and blood pressure. Black adults, in particular, are more likely to consume less potassium, have inadequate hydration, and tend to have higher blood pressure. As such, there is a critical need for effective strategies to address racial disparities in hydration and resultant health consequences; as well as establish the role of socioeconomic factors contributing to hydration. Therefore, the investigators are seeking to test the investigators' central hypothesis that water with a potassium supplement will improve hydration and cardiovascular health in young White adults (n = 20, 10 females, 10 males), and to a greater extent in young Black Adults (n = 20, 10 females, 10 males. The investigators will assess measures of blood pressure, arterial stiffness, and biomarkers in the urine and blood samples prior to and following a 14-day hydration intervention of 1) bottled water and 2) bottled water with potassium supplementation (2000mg potassium/day).

Study Overview

• Status: Recruiting
• Conditions: Blood Pressure; Hydration; Vascular Disease Risk
• Intervention / Treatment: Dietary supplement: Water and Potassium supplementation

Detailed Description

Compared with White adults, Non-Hispanic Black adults are at an elevated risk of developing cardiovascular disease (CVD) and end-stage chronic kidney disease (CKD) two of the leading causes of mortality in the United States (U.S.). Inadequate hydration status is associated with all-cause mortality and several risk factors for CVD and CKD including obesity, insulin resistance, hypertension, and metabolic syndrome. Prior data demonstrate Black American individuals are more likely to be hypohydrated (i.e., inadequately hydrated) when compared with White individuals. One study in emerging adults (18-25 years old) indicates that Black adults are more likely to be hypohydrated compared with White adults when assessed using gold-standard 24-hour urine collections. Socioeconomic factors influence hydration practices. For example, there are well-justified increased perceptions of unsafe tap water among racial and ethnic minorities. Indeed, the recent Flint, Michigan, and Jackson, Mississippi water crises have raised public awareness over these environmental injustices and ways to increase safe drinking water availability and access. However, there remains a critical need for empirical studies on 1) strategies to address racial disparities in hydration and resultant health consequences; and 2) the role socioeconomic factors in contributing to hydration.

Importantly, hypohydration is associated with increased production of arginine vasopressin (AVP), a peptide hormone produced in the hypothalamus that influences body water balance via anti-diuretic effects. Plasma copeptin is an established surrogate marker of circulating AVP concentration. Plasma copeptin is associated with incident type 2 diabetes, metabolic syndrome, the progression of CKD, and CVD. Some, but not all, studies have demonstrated racial differences in circulating AVP/copeptin. Further, prior studies that aimed at increasing water resulted in reductions in copeptin and improvements in cardiometabolic health. For example, in a cohort with high plasma copeptin, increased water intake also reduced fasting plasma glucose. In a cohort of adults with overweight and obesity, increased water or low-calorie beverage intake reduced fasting plasma glucose and contributed to modest weight loss. Lastly, over 90% of adults do not meet recommendations for potassium intake. Importantly, potassium improves blood pressure (BP), particularly in Black adults, who tend to consume less potassium and have higher BP. Yet, there remains a knowledge gap regarding whether hydration intervention(s) inclusive of water (with or without) potassium could attenuate racial disparities in hydration status and circulating AVP/copeptin. Therefore, the investigators are seeking to test the investigators' central hypothesis that water with a potassium supplement (2000mg/day) will improve hydration and cardiovascular health in White adults (n = 20, 10 females, 10 males), and to a greater extent in young Black Adults (n = 20, 10 females, 10 males). The investigators will utilize three complementary specific aims to address the investigators' hypotheses:

Aim 1: Determine whether water with potassium supplementation improves hydration status and reduces circulating copeptin. The investigators hypothesize that water and potassium supplementation will improve hydration and renal biomarkers, including increased urine volume, and reduced urine specific gravity, urine osmolality, and plasma copeptin.

Aim 2: Determine whether water with potassium supplementation improves BP and vascular health. The investigators hypothesize that water and potassium supplementation will reduce resting laboratory BP and ambulatory BP (awake, asleep, and nocturnal BP dipping), and reduce arterial stiffness assessed via pulse wave velocity.

Aim 3: Determine whether socioeconomic factors are associated with hydration perceptions, knowledge, and practices. The investigators hypothesize that area deprivation index (ADI, i.e., more deprivation) will be associated with hydration perceptions (e.g., greater distrust of tap water) and inadequate hydration assessed by self-reported fluid intake and urine-specific gravity.

In summary, a knowledge gap remains in determining the underlying reasons for the consistently reported racial differences in hydration. To restate, the purpose of this study is to determine 1) whether prescribing water with potassium supplementation is efficacious at improving hydration and reducing plasma copeptin in Black and White adults; 2) whether improving hydration with supplemental potassium improves BP and vascular function in young Black and White adults; 3) Another area of innovation in the investigators' proposal is determining whether area deprivation index (ADI, i.e., more deprivation) is associated with and 3a) beliefs and practices around hydration and 3b) hydration status. 4) We also seek to determine whether the intervention leads to greater improvements in Black adults who are more likely to be underhydrated.

• Study Type: Interventional
• Enrollment (Estimated): 40
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Nina L Stute, M.S.; Phone Number: 9373071608; Email: NLS0028@auburn.edu
• Study Contact Backup: Name: Meral A Culver, M.S.; Phone Number: 3017428813

Study Locations

• United States
  • Alabama
    • Auburn, Alabama, United States, 36849
      • Recruiting
      • Kinesiology Building
      • Contact: Nina L Stute, MS; Phone Number: 334-844-1619; Email: nls0028@auburn.edu

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Between the ages of 18-30 years
• Resting blood pressure no higher than 150/90 mmHg
• BMI below 35 kg/m2
• Free of any metabolic disease (e.g., diabetes) kidney disease, pulmonary disorders (e.g., COPD), cardiovascular disease (peripheral vascular, cardiac, or cerebrovascular), no autoimmune diseases, and no history of cancer.

Exclusion Criteria:

• Have any precluding medical conditions (i.e. hemophilia) or medication (Pradaxa, Eliquis, etc.) that prevent participants from giving blood.
• Are currently pregnant or trying to become pregnant.
• take any of the following medications that are contraindicated with potassium supplementation:
• Renin-angiotensin-aldosterone system (RAAS) blockers: Candesartan , Eprosartan, Irbesartan, Losartan, Olmesartan, Telmisartan
• Non -steroidal anti-inflammatory medications: Aspirin, Ibuprofen, Naproxen
• Non-selective beta-blockers: Pindolol, Penbutolol, Oxprenolol, Propranolol, Nadolol, Sotalol, Timolol, Tertatolol
• Calcineurin inhibitors: Cyclosporine
• Heparin (or other blood thinning medications)

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Prevention
• Allocation: Non-Randomized
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
No Intervention: Habitual consumption; N=40, 20 males, 20 females. All participants will be monitored after two weeks of habitual water and potassium prior to being assigned into two weeks of water and potassium.
Experimental: Water and Potassium; N=40, 20 males, 20 females. Following the two-week habitual run-in period, this group will receive 2000mg potassium supplementation/day for 14 days. This will be achieved by taking capsules filled with potassium chloride powder.	Dietary supplement: Water and Potassium supplementation; All Participants will be given cases of water and instructed to drink at least an extra 1L per day. Additionally, participants will be given 2000 mg of potassium via potassium chloride powder.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Urine specific gravity	24 urine samples will be aliquoted and assessed for urine specific gravity (unitless)	Change score from habitual consumption to after the hydration interventions (2 weeks)
Urine osmolality	24 urine samples will be aliquoted and assessed for urine osmolality in mOsm/kg (AI Osmometer 3D3)	Change score from habitual consumption to after the hydration interventions (2 weeks)
Urine flow rate	24 urine samples will be assessed for urine flow rate based on urine volume and self-reported collection time (ml/min).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Plasma copeptin	Plasma copeptin concentration (picomoles per liter) from a resting blood draw	Change score from habitual consumption to after the hydration interventions (2 weeks)
24-hour ambulatory blood pressure	Participants will wear an Oscar2 (with SphygmoCor) ambulatory blood pressure monitor on their upper arm for up to 24-hours preceding their study visit to measure systolic and diastolic blood pressure. The purpose of the ambulatory blood pressure monitoring is to determine blood pressure regulation over an entire day. This blood pressure monitor will be set to automatically take blood pressure every 20 minutes. The monitor records and saves each blood pressure measurement automatically.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Pulse wave velocity	The investigators will use the SphygmoCor XCEL system to assess pulse wave velocity (PWV meters per second). A high-fidelity transducer is used to obtain the pressure waveform at the carotid pulse. Distances from the carotid artery sampling site to the femoral artery (upper leg instrumented with a thigh cuff for oscillometric sphygmomanometry), and from the carotid artery to the suprasternal notch will be recorded. PWV will be expressed as cm/s.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Pulse wave analysis	The investigators will use the SphygmoCor XCEL system to assess pulse wave analysis (PWA) The sampling site is the brachial artery (upper alarm instrumented with a cuff for oscillometric sphygmomanometer). PWA will be expressed as a percentage (calculated as augmentation pressure divided by the pulse pressure).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Brachial blood pressure	Seated rachial blood pressure will be measured triplicate after at least 5 minutes of rest using an oscillometric device (Suntech CT 40)	Change score from habitual consumption to after the hydration interventions (2 weeks)

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Kidney blood velocity	Renal and segmental artery blood velocity will be assessed in the decubitis position using a high-frequency ultrasound probe, typically in the range of 3-5 MHz.Using Spectral Doppler, the peak systolic velocity (PSV) in the renal and segmental arteries will be measured.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Plasma Osmolality	Researchers will analyze blood samples for osmolarity (AI Osmometer 3D3)	Change score from habitual consumption to after the hydration interventions (2 weeks)
Plasma electrolytes	Researchers will analyze plasma samples for electrolytes (Na, K, Cl) concentration using the SmartLyte Electrolyte Analyzer. The unit of measure for Na, K, and Cl is millimoles per liter (mmol/L).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Blood glucose	Researchers will analyze whole blood samples for blood glucose concentration in milligrams per deciliter using Cholestech benchtop analyzer	Change score from habitual consumption to after the hydration interventions (2 weeks)
Objective sleep duration	Philips actiwatch spectrum will be used to quantify sleep duration in hours. Participants will wear the watch units for 14 days. The investigators will assess sleep duration and cross-check actigraphy wear times with a sleep diary.	Pre-intervention (14 days)
Objective sleep efficiency	Philips actiwatch spectrum will be used to quantify the percentage of time in bed actually spent sleeping to calculate sleep efficiency.	Pre-intervention (14 days)
Urine electrolytes	Researchers will analyze 24-hour urine samples for electrolytes (Na, K, Cl) content using the SmartLyte Electrolyte Analyzer. The unit of measure for Na, K, and Cl is milliequivalents (mEq).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Inflammatory cytokine responses	Plasma will be used for a multiplex to measure inflammatory cytokines tumor necrosis factor-alpha, interleukin-6, monocyte chemoattractant protein-1, and interleukin-1. These biomarkers will be measured by enzyme-linked immunosorbent assays (ELISAs) from R&D.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Dietary intake	The investigators will instruct participants to complete a diet log for 3 days which will be operationalized with Nutrition Data System for Research (NDSR).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Subjective sleep duration	The investigators will use the Pittsburgh Sleep Quality Index (PSQI) to assess sleep duration reflective of the one-month period leading into the study. The global PSQI score can range from 0 to 21 points, however, this outcome specifically refers to self-reported sleep duration in hours.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Subjective sleep quality	The investigators will use the Pittsburgh Sleep Quality Index (PSQI) to assess perceived sleep quality reflective of the one-month period leading into the study. The global PSQI score can range from 0 to 21 points.	Change score from habitual consumption to after the hydration interventions (2 weeks)

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Physical activity	Participants will wear an ActiGraph GT3X accelerometer for 14 days to objectively quantify steps taken per day.	Pre-intervention (intake visit)
Blood pressure reactivity responses	The investigators will measure systolic and diastolic pressure using photoplethysmography at the finger and manually measure brachial pressures in millimeters of mercury. Systolic and diastolic blood pressure will be assessed at rest and during a cold pressor test. Blood pressure reactivity will be expressed as a change in pressure (mmHg) from baseline to the last 30 seconds of the cold pressor test.	Change score from habitual consumption to after the hydration interventions (2 weeks)
Hemoglobin	Whole blood samples will be analyzed for hemoglobin concentration (HemoCue, radiometer)	Change score from habitual consumption to after the hydration interventions (2 weeks)
Hematocrit	Whole blood samples will be analyzed for hematocrit as a percentage (Thermo Hematocrit Microcentrifuge).	Change score from habitual consumption to after the hydration interventions (2 weeks)
Area deprivation index	Investigators will measure participant's area deprivation index (ADI) based on their self-reported zip code. The ADI is a multidimensional assessment of a region's socioeconomic conditions. It is used to measure and quantify the level of deprivation or disadvantage experienced by residents in a specific geographical area. The composite score will be standardized to have a mean of 100 and a standard deviation of 20 to assist interpretation.	Pre-intervention (intake visit)

Collaborators and Investigators

• Sponsor: Auburn University
• Collaborators: Indiana University
• Investigators: Study Director: L. Bruce Gladden, Ph.D., Auburn University; Study Director: Austin T Robinson, Ph.D., Indiana University

Publications and helpful links

General Publications

• Fuller-Rowell TE, Nichols OI, Robinson AT, Boylan JM, Chae DH, El-Sheikh M. Racial disparities in sleep health between Black and White young adults: The role of neighborhood safety in childhood. Sleep Med. 2021 May;81:341-349. doi: 10.1016/j.sleep.2021.03.007. Epub 2021 Mar 12.
• Brooks CJ, Gortmaker SL, Long MW, Cradock AL, Kenney EL. Racial/Ethnic and Socioeconomic Disparities in Hydration Status Among US Adults and the Role of Tap Water and Other Beverage Intake. Am J Public Health. 2017 Sep;107(9):1387-1394. doi: 10.2105/AJPH.2017.303923. Epub 2017 Jul 20.
• Onufrak SJ, Park S, Sharkey JR, Sherry B. The relationship of perceptions of tap water safety with intake of sugar-sweetened beverages and plain water among US adults. Public Health Nutr. 2014 Jan;17(1):179-85. doi: 10.1017/S1368980012004600. Epub 2012 Oct 26.
• Onufrak SJ, Park S, Sharkey JR, Merlo C, Dean WR, Sherry B. Perceptions of tap water and school water fountains and association with intake of plain water and sugar-sweetened beverages. J Sch Health. 2014 Mar;84(3):195-204. doi: 10.1111/josh.12138.
• Park S, Onufrak SJ, Cradock AL, Patel A, Hecht C, Blanck HM. Perceptions of Water Safety and Tap Water Taste and Their Associations With Beverage Intake Among U.S. Adults. Am J Health Promot. 2023 Jun;37(5):625-637. doi: 10.1177/08901171221150093. Epub 2023 Jan 6.
• Robinson AT, Linder BA, Barnett AM, Jeong S, Sanchez SO, Nichols OI, McIntosh MC, Hutchison ZJ, Tharpe MA, Watso JC, Gutierrez OM, Fuller-Rowell TE. Cross-sectional analysis of racial differences in hydration and neighborhood deprivation in young adults. Am J Clin Nutr. 2023 Oct;118(4):822-833. doi: 10.1016/j.ajcnut.2023.08.005. Epub 2023 Aug 22.

Study record dates

Study Major Dates

• Study Start (Actual): November 6, 2024
• Primary Completion (Estimated): July 1, 2026
• Study Completion (Estimated): July 1, 2027

Study Registration Dates

• First Submitted: September 20, 2023
• First Submitted That Met QC Criteria: September 25, 2023
• First Posted (Actual): October 2, 2023

Study Record Updates

• Last Update Posted (Actual): March 25, 2025
• Last Update Submitted That Met QC Criteria: February 25, 2025
• Last Verified: February 1, 2025

More Information

Terms related to this study

• Keywords: Hydration; Blood pressure; Potassium; Vascular function; Racial disparities
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases
• Other Study ID Numbers: #23-381

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: YES
• IPD Plan Description: Unidentified individual participant data will be made available to other researchers upon reasonable request and data and material transfer agreement
• IPD Sharing Time Frame: 2 years after completion of the study, indefinitely
• IPD Sharing Access Criteria: Unidentified individual participant data will be made available to other researchers upon reasonable request and data and completion of a material transfer agreement with Auburn University.
• IPD Sharing Supporting Information Type: STUDY_PROTOCOL; SAP; ANALYTIC_CODE

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No