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

Official title

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

Overview

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.

Interventions

• Other Low-potassium, ultra-processed diet
  A diet restricted in potassium, primarily composed of industrially processed foods such as packaged snacks and processed meals.
• 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.
• 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.
• 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

Primary outcome measures

• Fasting Serum Potassium Levels (mmol/L) [Time frame: Days 10, 36, 62, and 88.]

Secondary outcome measures (6)

• 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.]
• Potassium Bioavailability [Time frame: Days 7-9, 33-35, 59-61, 85-87.]
• Body Composition (kg) [Time frame: Baseline and days 10, 36, 62, and 88.]
• Body water (L) [Time frame: Baseline and days 10, 36, 62, and 88.]
• 24h blood pressure (mmHg) [Time frame: Days 8-10, 34-36, 60-62, and 86-88.]
• Dietary Satisfaction Questionnaire [Time frame: Days 10, 36, 62, and 88.]

Eligibility criteria

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.

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

Randomized

Model

Crossover

Masking

Open label

Primary purpose

Basic science

Study locations

Center list to be confirmed — check the primary protocol.

Publications

• Picard K, Barreto Silva MI, Mager D, Richard C. Dietary Potassium Intake and Risk of Chronic Kidney Disease Progression in Predialysis Patients with Chronic Kidney Disease: A Systematic Review. Adv Nutr. 2020 Jul 1;11(4):1002-1015. doi: 10.1093/advances/nmaa027. PMID 32191264
• Picard K, Mager DR, Senior PA, Richard C. Potassium-Based Sodium Substitutes Impact the Sodium and Potassium Content of Foods. J Ren Nutr. 2025 Jan;35(1):64-71. doi: 10.1053/j.jrn.2024.05.010. Epub 2024 Jun 6. PMID 38848804
• Picard K. Potassium Additives and Bioavailability: Are We Missing Something in Hyperkalemia Management? J Ren Nutr. 2019 Jul;29(4):350-353. doi: 10.1053/j.jrn.2018.10.003. Epub 2018 Dec 19. PMID 30579674
• Picard K, Picard C, Mager DR, Richard C. Potassium content of the American food supply and implications for the management of hyperkalemia in dialysis: An analysis of the Branded Product Database. Semin Dial. 2024 Jul-Aug;37(4):307-316. doi: 10.1111/sdi.13007. Epub 2021 Jul 29. PMID 34323307
• Picard K RD BSc, Senior PA MBBS PhD FRCP(E) FRCP, Wilmott A BSc, Jindal K MD FRCPC, Richard C RD PhD, Mager DR RD PhD. Comparison of diet quality tools to assess nutritional adequacy for adults living with kidney disease. Can J Diet Pract Res. 2022 Dec 1;83(4):180-185. doi: 10.3148/cjdpr-2022-009. Epub 2022 May 3. PMID 35503893
• Picard K, Senior PA, Adame Perez S, Jindal K, Richard C, Mager DR. Low Mediterranean Diet scores are associated with reduced kidney function and health related quality of life but not other markers of cardiovascular risk in adults with diabetes and chronic kidney disease. Nutr Metab Cardiovasc Dis. 2021 May 6;31(5):1445-1453. doi: 10.1016/j.numecd.2021.02.002. Epub 2021 Feb 11. PMID 33812736
• Picard K, Griffiths M, Mager DR, Richard C. Handouts for Low-Potassium Diets Disproportionately Restrict Fruits and Vegetables. J Ren Nutr. 2021 Mar;31(2):210-214. doi: 10.1053/j.jrn.2020.07.001. Epub 2020 Aug 20. PMID 32830022

Identifiers

NCT: NCT06920914 · Pro00139586 · RES0062629

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗