BACKGROUND: Chronic Kidney Disease (CKD) is associated with alterations in phosphorus excretion, and increases in fibroblast growth factor (FGF23) and parathyroid hormone (PTH). Plant protein-based phytate-bound phosphorus, is less bioavailable than that from animal sources. Our one-week study that was conducted previously showed that a nearly 100% plant protein-based diet benefits mineral metabolism in CKD; however, this diet may not be acceptable to patients. Here we hypothesize that a diet containing 70% protein from plants has similar efficacy and is tolerated by CKD patients.
METHODS: Thirteen subjects with CKD 3-4 received an omnivorous diet containing 70% protein from plants for 4 weeks. The primary outcome was change in 24 h urine phosphorus. Secondary outcomes were changes in serum phosphorus, FGF23, PTH, urine sodium excretion, grip strength and fat free mass. Repeated measures analysis of variance (ANOVA) was used to test differences in parameters over the 4 weeks.
RESULTS: Mean age of subjects was 54.8 years. Median eGFR was 26 (IQR 14.7) ml/min/1.73 m(2). Over the 4-week period, urine phosphorus significantly decreased by 215 ± 232 mg/day (p < 0.001). No significant changes in serum FGF23, phosphorus or PTH were noted. Urine sodium and titratable acid decreased significantly on the diet. Hand grip strength and fat-free mass did not change. There were two hyperkalemia events both 5.8 mEq/l, corrected by food substitutions. No other adverse events were observed.
CONCLUSIONS: A 70% plant protein diet is safe, tolerated, and efficacious in lowering urine phosphorus excretion and may be an alternative to phosphate binders
