A review of issues of dietary protein intake in humans

Background: Dietary protein has long been thought to play a role in the progression of chronic renal disease, but clinical trials to date have not consistently shown that dietary protein restriction is beneficial. Purpose: To use meta-analysis to assess the efficacy of dietary protein restriction in previously published studies of diabetic and nondiabetic renal diseases, including the recently completed Modification of Diet in Renal Disease Study. Data Sources: The English-language medical literature published from January 1966 through December 1994 was searched for studies examining the effect of low-protein diets in humans with chronic renal disease. A total of 1413 patients in five studies of nondiabetic renal disease (mean length of follow-up, 18 to 36 months) and 108 patients in five studies of type I diabetes mellitus (mean length of follow-up, 9 to 35 months) were included. Study Selection: Randomized, controlled studies were selected for nondiabetic renal disease; randomized, controlled studies or time-controlled studies with nonrandomized crossover design were selected for diabetic nephropathy. Data Extraction: Data in tables, figures, or text were independently extracted by two of the authors.