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NCT Number: NCT06920914

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

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Key information

Conditions

Chronic Kidney Disease Chronic Disease Disease Attributes Female Urogenital Diseases Female Urogenital Diseases and Pregnancy Complications Hyperkalemia Kidney Diseases Male Urogenital Diseases Metabolic Diseases Nutritional and Metabolic Diseases Pathologic Processes Pathological Conditions, Signs and Symptoms Renal Insufficiency Renal Insufficiency, Chronic Urogenital Diseases Urologic Diseases Water-Electrolyte Imbalance

Age range

18 year and older

Sex eligibility

All sexes

Study type

Interventional

Phase

Not applicable

Who can participate

Healthy volunteers accepted: No

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

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.

Treatment and study plan

Low-potassium, ultra-processed diet

Other

A diet restricted in potassium, primarily composed of industrially processed foods such as packaged snacks and processed meals.

Low-potassium, minimally processed diet

Other

A diet restricted in naturally occurring potassium, primarily composed of fresh fruits, vegetables, whole grains, and other minimally processed foods.

Normal potassium-rich, minimally processed diet

Other

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.

Normal potassium-rich, ultra-processed diet

Other

A diet with normal potassium content, primarily composed of industrially processed foods such as packaged snacks and processed meals

Primary outcomes

  1. 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.

Secondary outcomes

  1. 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.

  2. 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.

  3. 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).

  4. 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.

  5. 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.

  6. 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.

Other outcomes

  1. 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.

  2. 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.

  3. 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.

  4. 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.

Study contacts

Contact information is provided by the study sponsor or research team.

Jenneffer Rayane Braga Tibaes, PhD

CONTACT

[email protected]

7804929506

Sponsors and collaborators

Lead sponsor

University of Alberta

Other

Collaborators

  • Canadian Institutes of Health Research (CIHR)

Registry information

Official study title

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

Acronym: K-HANDLE CKD

Important dates

Study start
2026
Primary completion
2027
Study completion
2028
First posted
Apr 10, 2025
Registry last updated
Feb 5, 2026

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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