BackgroundPlant-based diets (PBD) may induce hyperkalemia in chronic kidney disease (CKD) patients. ObjectiveWe explored safety and feasibility of PBD in hyperkalemic CKD patients receiving the potassium binder sodium zirconium cyclosilicate (SZC). MethodsIn the current 6-weeks trial, 26 hyperkalemic patients with CKD stage 4-5 not on dialysis received a low-protein low-potassium diet plus SZC for three weeks and then a PBD with high potassium content delivered as weekly food basket while continuing SZC for subsequent three weeks. Plasma potassium was monitored weekly and SZC was titrated to achieve normokalemia. The 24-hour urine excretion of potassium and sodium, 24-hour food records, dietary quality, nutritional status, Bristol stool scale, quality of life (QoL) and renal treatment satisfaction were assessed at baseline (week 0), week 3 and week 6. ResultsMean plasma potassium decreased from 5.5 to 4.4 mEq/L within 48-72 hours after baseline, then rose to 4.7-5.0 mEq/L throughout the remaining study period following dose adjustments of SZC that matched the increased potassium intake of PBD from Week 3 to Week 6. 24-hour urinary potassium excretion decreased from Week 0 to Week 3 and increased from Week 3 to Week 6. 58% of patients had fasting plasma potassium between 3.5 to 5.0 mEq/L and there was no episode of plasma potassium >6.5 mEq/L or <3.0 mEq/L during the study. P-carbon dioxide increased from baseline until Week 6 (21±2 to 23±2 mEq/L; p=0.002; mean±standard deviation) while remaining laboratory values remained unchanged. Fiber intake, dietary quality, the domain physical functioning from QoL and one question of renal treatment satisfaction improved while stool type and frequency did not change after starting PBD. ConclusionsPBD in hyperkalemia-prone CKD patients receiving SZC improved dietary quality and increased the intake of healthy foods while plasma potassium concentration remained stable within normal values for most patients.Clinical Trial Registry number NCT04207203 (https://clinicaltrials.gov/study/NCT04207203).