A Cross-Sectional Study on the Effects of Long Term Very Low Protein Diets in Patients with Chronic Kidney Disease

Background: Chronic renal failure has increased among aged population in Japan. Protein-restricted diets have been successfully used to treat chronic renal failure. However, concerns over sarcopenia and other nutritional disorders have made doctors in Japan reluctant to recommend low-protein diets.Study Design: A cross-sectional study was carried out based on dietary records, urine and blood samples and DEXA measurements to evaluate body composition.Setting & Participants: The study was carried out at Keio University Hospital and National Institute of Health and Nutrition, Tokyo, over the 3-day period in June, 2009. Subjects were 10 CKD patients (1 male, 9 female); ten members of the patients’ families (3 male, 7 female) and 11 dieticians (all female) were used as control subjects.Factor: The CKD patients maintained a daily protein intake of less than 0.5 g/kg body weight (VLPD) for periods averaging 7 years. Members of the control group all had a daily protein intake of over 1g/kg body weight.Outcomes: Indicators of nutritional disorders, metabolic abnormalities or changes in body composition were sought.Measurements: Intake of various nutrients was calculated from dietary records. Blood plasma and urine content was analyzed. Body composition was measured using DEXA.Results: The CKD subjects were found not to suffer from sarcopenia, osteoporosis, hyperkalemia, hyperphosphatemia, hyperuremia or high levels of uric acid, although slight anemia was observed. Vitamin and mineral intakes were lower than controls, but no recognizable symptoms from nutrient deficiency occurred. Urinary excretion of amino acids was different from controls.Limitations: Results are limited by the relatively small number of test subjects, variation in time on the VLPD, and gender imbalance.Conclusion: Results suggest that VLPD did not show any abnormality in body composition when energy requirement was fulfilled. Different amino acid metabolism would lead to cautious prescription of amino acid supplement.