The Effect of Higher and Lower Protein Intakes on Nitrogen Balance in Renal Transplant Recipients with Underlying Graft Dysfunction

Abstract

It is essential to determine the optimum protein intake in renal transplant recipients on steroids with renal dysfunction to maintain a neutral nitrogen balance. Our aim was to study the effect of higher (1.2 g/kg/day) and lower (0.8 g/kg/day) protein intakes on nitrogen balance, body composition, glomerular filtration rate (GFR), and proteinuria in renal transplant recipients with low estimated GFR (eGFR) (15–44 mL/min/1.73 m2). This prospective, open-labeled, randomized, cross-over, interventional study enrolled patients who were ≥4 months posttransplant with eGFR between 15 and 44 mL/min/1.73 m2. Subjects were randomized to either Group 1 [Diet: proteins (1.2 g/kg/day), 35 kcal/kg/day] or Group 2 [Diet: proteins (0.8 g/kg/day) and 35 kcal/kg/day] for one month. Subjects crossed over to the other diet for 2nd month. Body composition analysis, serum creatinine, blood urea nitrogen, serum protein, serum albumin, 24-h proteinuria, GFR measurement (24 h creatinine clearance), three-day diet recall and nitrogen balance estimation were performed at baseline and at the end of the first and 2nd month. Statistical analysis was performed using IBM SPSS Statistics version 21. Thirty-two of 35 patients completed the study. Three-day diet recall showed that daily protein and energy consumption was 1.2 g/kg and 36.47 kcal/kg with higher and 0.94 g/kg and 31.94 kcal/kg with lower protein diets, respectively. Nitrogen balance was +3.61 g/day (P = 0.0002) with higher and +1.66 g/day with lower protein diets. A significant increase was noted in muscle mass (P = 0.0317), blood urea nitrogen (P = 0.0118), GFR (P = 0.0114), and proteinuria (P = 0.010) with a higher protein diet. Renal transplant recipients remained in positive nitrogen balance with both diets. Muscle mass and proteinuria increased significantly with a higher protein diet.