Effects of Minimally vs. Ultra-Processed Diets on Potassium (K) Handling in CKD (K-HANDLE CKD)

February 3, 2026 updated by: University of Alberta

Potassium (K) Handling in Advanced Chronic Kidney Disease (K-HANDLE CKD)

What is this study about?

This clinical trial is designed to learn how potassium from different types of food affects blood potassium levels and overall health in people with chronic kidney disease (CKD, stages 3B-5).

People with CKD are often advised to avoid potassium-rich foods, even though fresh fruits and vegetables are important for good health. However, potassium in processed foods (such as packaged snacks and ready-made meals) may be absorbed differently than potassium from fresh foods.

This study will compare minimally processed vs. ultra-processed foods to determine how different sources of potassium affect potassium levels and help create better dietary recommendations for people with CKD.

What are the study goals?

The study will answer:

  • Does potassium from fresh foods (like fruits and vegetables) affect blood potassium differently than potassium from processed foods?
  • How does dietary potassium impact potassium absorption and excretion in people with CKD?

Researchers will compare the effects of four diets to understand how low and normal-potassium rich diets from fresh vs. processed foods influence:

  • Blood potassium levels
  • Body composition (muscle, fat, and fluid balance)
  • Vascular health

What will participants do?

Participants will follow four different 10-day diets over the course of the study. All food will be provided at no cost. These diets are:

  • Minimally processed with low-potassium content
  • Minimally processed with normal potassium content
  • Ultra-processed with with low-potassium content
  • Ultra-processed with normal potassium content

There will be 16-day breaks (washout period) between diets where participants return to their normal eating habits.

During the study, participants will:

  • Pick up prepared meals from the research center approximately 3 times per week.
  • Attend checkups for weight, blood pressure, and blood tests.
  • Provide urine samples to track potassium levels.
  • Wear a comfortable, cuff-free blood pressure monitor at home.
  • Keep a study journal to track diet, medications, and symptoms.
  • Complete questionnaires about diet satisfaction and health changes.

Study Overview

Status

Not yet recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Estimated)

48

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Participants aged ≥18 years living with stage 3B-5 CKD (estimated glomerular filtration rate ≥ 15 mL/min/1.73m2) on conservative kidney management (not on dialysis).
  • Able and willing to follow a controlled feeding regimen, attend in-person visits, provide informed consent, and comply with study procedures.

Exclusion Criteria:

General

  • Pregnant or lactating women.
  • Transitioning transgender individuals.
  • Individuals with strict dietary preferences (e.g., vegetarians, vegans) or allergies/intolerance that would preclude participation in the diet phases.

Kidney Function

  • Foreseen start of renal replacement therapy within the next 6 months.
  • Acute kidney injury in the past 3 months.
  • 2-year Kidney Failure Risk Equation > 40%.
  • Preemptive kidney transplant planned within the next 6 months.
  • History of kidney transplant.
  • Active glomerulonephritis. Comorbidities
  • Acute myocardial infarction or stroke within the past 6 months.
  • Active cancer.
  • Ileostomy, short bowel syndrome or inflammatory bowel disease.
  • Body mass index < 18.5 or ≥ 35.
  • New York Heart Association Class III or IV congestive heart failure.
  • History of ventricular arrhythmia.
  • Major surgery within the past 3 months.
  • Active autoimmune disease.
  • Glycated hemoglobin > 10% within the past 3 months.
  • Gastroparesis.
  • Chronic nausea and vomiting.
  • Intensive care unit admission within the past 3 months.
  • Significant psychiatric disease.
  • Uncontrolled blood pressure (above 160/100). Current Use of Medications/Supplements
  • Immunosuppressives.
  • Potassium binders.
  • Lithium.
  • Motility agents.
  • More than 2 medications that inhibit renal potassium excretion (e.g., angiotensin-converting enzyme inhibitors, angiotensin II receptor blockers, mineralocorticoid receptor antagonists).
  • Supplements known to influence potassium levels. Potassium-Related Conditions
  • Potassium > 5.5 mmol/L in more than 3 episodes within the past year.
  • Participants with genetic issues affecting potassium handling (e.g. Barter and Liddle syndrome) or other unique health conditions that could interfere with potassium handling.

Intervention-related Conditions

  • Fluid volume status or hypertension being actively managed. Other Factors
  • Documented non-adherence to medications or other therapeutic measures.
  • Use of tube feeding or parenteral nutrition.

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Randomized
  • Interventional Model: Crossover Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Low-potassium, ultra-processed diet
Participants in this group will follow a diet consisting of ultra-processed foods with restricted potassium content.
Other: Low-potassium, ultra-processed diet
A diet restricted in potassium, primarily composed of industrially processed foods such as packaged snacks and processed meals.
Experimental: Normal potassium-rich, minimally processed diet
Participants in this group will follow a diet consisting of minimally processed foods with a normal potassium content.
Other: Normal potassium-rich, minimally processed diet
A diet with normal potassium content, primarily composed of fresh fruits, vegetables, whole grains, and other minimally processed foods, rich in naturally occurring potassium, following a Mediterranean-style pattern.
Experimental: Normal potassium-rich, ultra-processed diet
Participants in this group will follow a diet consisting of ultra-processed foods with a normal potassium content.
Other: Normal potassium-rich, ultra-processed diet
A diet with normal potassium content, primarily composed of industrially processed foods such as packaged snacks and processed meals
Experimental: Low-potassium, minimally processed diet
Participants in this group will follow a diet consisting of minimally processed foods with restricted potassium content.
Other: Low-potassium, minimally processed diet
A diet restricted in naturally occurring potassium, primarily composed of fresh fruits, vegetables, whole grains, and other minimally processed foods.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Fasting Serum Potassium Levels (mmol/L)
Time Frame: Days 10, 36, 62, and 88.
This measure assesses the concentration of potassium in participants' blood after fasting overnight. Normal potassium levels typically range from 3.5 to 5.0 mmol/L.
Days 10, 36, 62, and 88.

Secondary Outcome Measures

Outcome Measure
Measure Description
Time Frame
Body Composition (kg)
Time Frame: Baseline and days 10, 36, 62, and 88.
This measure estimates participants' fat mass and fat-free mass. Body composition is assessed using bioelectrical impedance analysis, which uses safe, low-level electrical currents to estimate tissue and fluid distribution. Results are reported in kilograms (kg).
Baseline and days 10, 36, 62, and 88.
Body water (L)
Time Frame: Baseline and days 10, 36, 62, and 88.
This measure evaluates fluid status, i which plays a role in potassium handling. Body water is estimated using bioelectrical impedance analysis, which uses safe, low-level electrical currents to estimate tissue and fluid distribution. Results are reported in liters for total, extracellular, and intracellular water.
Baseline and days 10, 36, 62, and 88.
24h blood pressure (mmHg)
Time Frame: Days 8-10, 34-36, 60-62, and 86-88.
Systolic and diastolic blood pressure will be monitored for 24h.
Days 8-10, 34-36, 60-62, and 86-88.
Dietary Satisfaction Questionnaire
Time Frame: Days 10, 36, 62, and 88.
Self-administered questionnaire to provide feedback on the palatability, variety, and overall acceptability of the study-provided diets.
Days 10, 36, 62, and 88.
Postprandial Whole-Blood Potassium Response (mmol/L)
Time Frame: 15, 30, 60, 90, 120, 150, 180 minutes post-meal at days 10, 36, 62, and 88.
This measure examines changes in blood potassium levels after a standardized test meal. Blood samples are collected before the meal (baseline) and at regular intervals (15, 30, 60, 90, 120, 150, and 180 minutes) to calculate the area under the curve (AUC), which reflects the total potassium response over time.
15, 30, 60, 90, 120, 150, 180 minutes post-meal at days 10, 36, 62, and 88.
Potassium Bioavailability
Time Frame: Days 7-9, 33-35, 59-61, 85-87.
Potassium bioavailability is assessed by measuring the potassium content in 24-hour urine samples. This provides insights into how much potassium from the diet is absorbed and how much is excreted by the body.
Days 7-9, 33-35, 59-61, 85-87.

Other Outcome Measures

Outcome Measure
Measure Description
Time Frame
Hyperkalemic Events
Time Frame: Enrollment (Screening), baseline, and days 10, 36, 62, and 88.

The frequency and severity of hyperkalemic events (serum potassium ≥5.5 mmol/L) are monitored throughout the study to ensure participant safety.

Hyperkalemia episodes are recorded as a count of occurrences for each dietary phase. Evaluated at screening, baseline and Day 10 of each 10-day dietary phase.
Enrollment (Screening), baseline, and days 10, 36, 62, and 88.
Potassium Content in Foods (mg)
Time Frame: Before enrollment and through study completion, an average of 3 years
The potassium content of study-provided meals is measured to ensure accurate dietary potassium levels during each phase. Measured during the menu development phase and throughout the study.
Before enrollment and through study completion, an average of 3 years
Phosphorus Content in Foods (mg)
Time Frame: Before enrollment and through study completion, an average of 3 years
The phosphorus content of study-provided meals is measured to ensure accurate dietary phosphorus levels during each phase.Measured during the menu development phase and throughout the study.
Before enrollment and through study completion, an average of 3 years
Sodium Content in Foods (mg)
Time Frame: Before enrollment and through study completion, an average of 3 years
The sodium content of study-provided meals is measured to ensure accurate dietary sodium levels during each phase. Measured during the menu development phase and throughout the study.
Before enrollment and through study completion, an average of 3 years

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

University of Alberta

Collaborators

Canadian Institutes of Health Research (CIHR)

Investigators

  • Principal Investigator: Caroline Richard, PhD, University of Alberta
  • Principal Investigator: Branko Braam, MD, PhD, University of Alberta

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Estimated)

July 1, 2026

Primary Completion (Estimated)

December 1, 2027

Study Completion (Estimated)

June 1, 2028

Study Registration Dates

First Submitted

December 10, 2024

First Submitted That Met QC Criteria

April 2, 2025

First Posted (Actual)

April 10, 2025

Study Record Updates

Last Update Posted (Actual)

February 5, 2026

Last Update Submitted That Met QC Criteria

February 3, 2026

Last Verified

February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • Pro00139586
  • RES0062629 (Other Grant/Funding Number: Canadian Institutes of Health Research)

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

NO

IPD Plan Description

We have not yet finalized a plan for sharing individual participant data. The decision will depend on several factors, including participant consent, ethical approval, and institutional policies regarding data privacy and security. Future data sharing may be considered upon additional ethical review and participant consent.

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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