The impact of protein source on serum potassium and phosphate levels in adults living with advanced kidney disease.

Background And Aims: Plant proteins may be restricted on low potassium/phosphorus diets. The primary objective was to investigate the impact of protein source on serum potassium and phosphate levels in adults with stage 4-5 chronic kidney disease (CKD), including hemodialysis (HD).

Methods And Results: Using a cross-sectional design, 24-h recalls or food frequency questionnaires were used to assess dietary intake. Serum values were obtained from medical records. Quartiles (Q1-4) of plant:animal protein serving ratios was considered to investigate outcomes, with Q1 having high animal and low plant serving intake and those in Q4 having high plant and low animal servings. 216 participants were enrolled, 135 on HD and 81 stage 4/5 CKD. For both HD and CKD, there was no difference in either serum potassium or phosphate levels between those in Q4 consuming high plant:animal vs Q1 low plant:animal (for HD: potassium 4.6 mmol/L vs 4.6 mmol/L; phosphate 1.8 mmol/L vs 1.6 mmol/L, respectively; for CKD: potassium 4.7 mmol/L vs 4.6 mmol/L; phosphate 1.4 mmol/L vs 1.4 mmol/L; all p > 0.05). Those in Q4 consuming high plant:animal consumed 7.5 g (62%) more fibre than those in Q1 (low plant:animal). For diet quality, Q4 (high plant:animal) had a 12.8 point (24%) higher healthy eating index score than Q1 (low plant:animal). There was no relationship between plant:animal and serum albumin or hospital admissions (all p > 0.05).

Conclusions: Consumption of higher proportions of plant protein was not associated with higher serum potassium or phosphate levels but was associated with higher fibre and diet quality.