Short-term effects of a very-low-protein diet supplemented with ketoacids in nondialyzed chronic kidney disease patients

Objective: To evaluate the effects on the nutritional and metabolic parameters of a very-low-protein diet supplemented with ketoacids (VLPD+KA) in comparison with a conventional low-protein diet (LPD) in chronic kidney disease (CKD) patients. Design: Prospective, randomized, controlled clinical study. Setting: Outpatient Clinic of the Nephrology Division of Federal University of Sao Paulo, Brazil. Subjects: The study involved 24 patients with advanced CKD ( creatinine clearance <25 ml/min) that were randomly assigned to either a VLPD+KA (VLPD+KA group, 12 patients) or to a conventional LPD with 0.6 g/kg/day ( LPD group, 12 patients). The patients were followed for 4 months. Results: Nutritional status was adequately maintained with both diets for the studied period. Protein intake and serum urea nitrogen decreased significantly only in the VLPD+KA group ( from 0.68 +/- 0.17 to 0.43 +/- 0.12 g/kg/day, P<0.05; from 61.4 +/- 12.8 to 43.6 +/- 14.9 mg/dl, P<0.001; respectively). Ionized calcium did not change in the VLPD+KA group but tended to decrease in the LPD group. Serum phosphorus tended to decrease in the VLPD+KA group probably as a result of a significant reduction in dietary phosphorus (529 +/- 109 to 373 +/- 125 mg/day, P<0.05) associated to the phosphorus-binding effect of the ketoacids. No change in these parameters was found in the LPD group. Serum parathormone increased significantly only in the LPD group (from 241 +/- 138 to 494 +/- 390 pg/ ml, P<0.01). The change in PTH concentration was negatively correlated with changes in ionized calcium concentration ( r = - 0.75, P = 0.02) and positively correlated with changes in serum phosphorus ( r = 0.71, P = 0.03) only in the LPD group. Conclusion: This study indicates that a VLPD+KA can maintain the nutritional status of the patients similarly to a conventional LPD. Besides, an improvement in calcium and phosphorus metabolism and a reduction in serum urea nitrogen were attained only with the VLPD+KA. Thus, VLPD+KA can constitute another efficient therapeutic alternative in the treatment of CKD patients. Sponsorship: This study was supported by CAPES, Oswaldo Ramos Foundation and Fresenius Kabi, Ltda.