Inadequate energy and excess protein intakes may be associated with worsening renal function in chronic kidney disease

Objectives: Dietary energy and protein play important roles in chronic kidney disease (CKD). This study investigates the relationship between energy/protein intake status and renal function in CKD. Design and Study Population: This cross-sectional study included 599 adult patients diagnosed with stage 3 to 5 CKD in nephrology and nutrition outpatient clinics in Taiwan. Main Outcome Measure: Energy and protein intakes were assessed using 24-h dietary recall. We recorded recommended calorie/protein amounts and renal function indices, glomerular filtration rate (GFR), creatinine, and blood urea nitrogen (BUN). Patients were categorized into three intake calorie/protein groups by a ratio of actual intake vs. recommended intake. High intake was defined as a ratio of actual intake/recommended intake >= 110%, moderate intake as >= 90% to <110%, and low intake as <90%. Data were analyzed by paired t test, one-way analysis of variance, least significant differences, and multiple linear regression. Results: The energy and protein intakes in CKD patients were significantly higher and lower than recommended levels (P <.001). Low energy intake was significantly related to worsening GFR at increments of -4.41 mL/min/1.73 m 2, compared with moderate and high energy intake (P =.008); high protein intake was also associated with worsening GFR at increments of -3.50 mL/min/1.73m(2), compared with moderate and low protein intake (P <.001). Low energy intake and high protein intake were significantly positively correlated with elevations in creatinine and BUN. Conclusion: Lower energy and higher protein intakes than recommended may be associated with deteriorating renal function. (C) 2008 by the National Kidney Foundation, Inc.