Branched-chain ketoacid co-ingestion with protein lowers amino acid oxidation during hemodialysis: A randomized controlled cross-over trial

Abstract

Hemodialysis removes amino acids from the circulation, thereby stimulating muscle proteolysis. Protein ingestion during hemodialysis can compensate for amino acid removal but may also increase uremic toxin production. Branched-chain ketoacid (BCKA) co-ingestion may provide an additional anabolic stimulus without adding to uremic toxin accumulation. In the present study we assessed the impact of BCKA co-ingestion with protein on forearm amino acid balance and amino acid oxidation during hemodialysis. Nine patients (age: 73±10y) on chronic hemodialysis participated in this crossover trial. During two 4-h hemodialysis sessions, patients ingested 18g protein with (PRO+BCKA) or without (PRO) 9g BCKAs in a randomized order. Test beverages were labeled with L-[ring-13C6]-phenylalanine and provided throughout the last 3h of hemodialysis as 18 equal sips consumed with 10-min intervals. Arterial and venous plasma as well as breath samples were collected frequently throughout hemodialysis. Arterial plasma total amino acid (TAA) concentrations during PRO and PRO+BCKA treatments were significantly lower after 1h of hemodialysis (2.6±0.3 and 2.6±0.3mmol/L, respectively) when compared to pre-hemodialysis concentrations (4.2±1.0 and 4.0±0.5mmol/L, respectively; time effect: P<0.001). Arterial plasma TAA concentrations increased throughout test beverage ingestion (time effect: P=0.027) without differences between treatments (time∗treatment: P=0.62). Forearm arteriovenous TAA balance during test beverage ingestion did not differ between timepoints (time effect: P=0.31) or treatments (time∗treatment: P=0.34). Whole-body phenylalanine oxidation was 33±16% lower during PRO+BCKA when compared to PRO treatments (P<0.001). BCKA co-ingestion with protein during hemodialysis does not improve forearm net protein balance but lowers amino acid oxidation.