Effects of a Personalized Diet on Nutritional Status and Renal Function Outcome in Nephrectomized Patients with Renal Cancer

Nutritional therapy (NT) based on a controlled protein intake represents a cornerstone in managing chronic kidney disease (CKD). However, if a CKD patient is at the same time affected by cancer, oncologists and nutritionists tend to suggest a dietary regimen based on high protein intake to avoid catabolism and malnutrition. International guidelines are not clear when we consider onco-nephrological patients and, as a consequence, no clinical shared strategy is currently applied in clinical practice. In particular, no precise nutritional management is established in nephrectomized patients for renal cell carcinoma (RCC), a specific oncological cohort of patients whose sudden kidney removal forces the remnant one to start a compensatory mechanism of adaptive hyperfiltration. Our study aimed to investigate the efficacy of a low-normal-protein high-calorie (LNPHC) diet based on a Mediterranean model in a consecutive cohort of nephrectomized RCC patients using an integrated nephrologist and nutritionist approach. A consecutive cohort of 40 nephrectomized RCC adult (age > 18) patients who were screened for malnutrition (malnutrition screening tool, MST < 2) were enrolled in a tertiary institution between 2020 and 2022 after signing a specific informed consent form. Each patient underwent an initial nephrological and nutritional evaluation and was subsequently subjected to a conventional CKD LNPHC diet integrated with aproteic foods (0.8 g/Kg/die: calories: 30-35 kcal per kg body weight/die) for a period of 6 months (±2 months). The diet was structured after considering eGFR (CKD-EPI 2021 creatinine formula), comorbidities, and nutritional status. MST, body mass index (BMI), phase angle (PA), fat mass percentage (FM%), fat-free mass index (FFMI), body cell mass index (BCMI), extracellular/intracellular water ratio (ECW/ICW), extracellular matrix/body cell mass ratio (ECM/BCM), waist/hip circumference ratio (WHC), lab test exams, and clinical variables were examined at baseline and after the study period. Our results clearly highlighted that the LNPHC diet was able to significantly improve several nutritional parameters, avoiding malnutrition and catabolism. In particular, the LNPHC diet preserved the BCM index (delta on median, ΔM + 0.3 kg/m2) and reduced the ECM/BCM ratio (ΔM - 0.03 *), with a significant reduction in the ECW/ICW ratio (ΔM - 0.02 *), all while increasing TBW (ΔM + 2.3% *). The LNPHC diet was able to preserve FFM while simultaneously depleting FM and, moreover, it led to a significant reduction in urea (ΔM - 11 mg/dL **). In conclusion, the LNPHC diet represents a new important therapeutic strategy that should be considered when treating onco-nephrological patients with solitary kidney due to renal cancer.