The role of low protein diet in ameliorating proteinuria and deferring dialysis initiation: what is old and what is new.

In the management of patients with chronic kidney diseases (CKD), a low-protein diet usually refers to a diet with protein intake of 0.6 to 0.8 grams per kilogram of body weight per day (g/kg/day) and should include at least 50% high-biologic-value protein. It may be supplemented with essential acids or nitrogen-free ketoanalogues if <0.6 g/kg/d. Low-protein diet can reduce proteinuria especially in non-diabetic CKD patients. In hypoalbuminemic patients it may lead to an increase in serum albumin level. By lowering proteinuria, decreasing nitrogen waste products, ameliorating metabolic burden, mitigating oxidative stress and acidosis, and lowering phosphorus burden, a low-protein diet can help delay dialysis start in advanced CKD. Low-protein diet is safe, since most CKD patients can maintain nitrogen balance by mechanisms of decreasing amino acid oxidation and protein degradation in addition to increased utilization of amino acids for protein synthesis. We suggest a dietary protein intake below 1.0 g/kg/day when estimated glomerular filtration rate (eGFR) falls below 60 mL/min/1.73 m2 or when there is solitary kidney or proteinuria at any level of GFR. Protein intake should be reduced progressively based on severity and progression of CKD and patient's nutritional status with a target of 0.6-0.8 g/kg/d in most patients with eGFR <45 mL/min/1.73 m2. The risk of protein-energy wasting can be overcome by careful attention to quantity and quality of the ingested proteins, sufficient energy intake of 30-35 Kcal/kg/d, and use of dietary supplements. Long-term observations and individualized approaches are needed to further demonstrate the benefits and safety of low-protein diet.