Dietary protein, exercise do not interfere with haemodialysis

Neither protein feeding nor physical activity interventions compromise the removal of uraemic toxins in end-stage renal disease patients on haemodialysis, reports a new study.

This randomized crossover trial included 10 patients (mean age 65 years, mean body mass index [BMI] 24.2 kg/m²) receiving long-term haemodialysis. Participants were assigned to receive 40 g of protein or a nonprotein placebo, both at rest and after 30 minutes of exercise.

Blood and spent dialysate samples were collected for the measurement of uraemic toxins, including urea, creatinine, phosphate, indoxyl sulphate, and cystatin C.

The reduction ratio for urea was significantly higher in patients after taking the placebo dietary intervention both at rest (76 percent) and after exercise (77 percent), as compared to the corresponding protein scenarios (72 percent and 73 percent; p=0.001 for protein effect).

A similar effect was reported for indoxyl sulphate, for which reduction ratios were significantly higher in the placebo vs protein arms both at rest (46 percent vs 40 percent) and after exercise (45 percent vs 43 percent; p=0.023 for protein effect).

These differences were driven mostly by diet, as the exercise effects in both cases failed to reach statistical significance (p=0.25 and p=0.52, respectively).

In contrast, protein intake correlated significantly with higher urea removal during haemodialysis (p=0.046). Meanwhile, clearance of creatinine, phosphate, and cystatin C was not affected by intradialytic protein ingestion.

Of note, exercise appeared to be important for urea, creatinine, and phosphate removal, all of which was found to be greater throughout the dialysis period in when measured after exercise vs at rest (p=0.034, p=0.039, and p=0.022, respectively).