End-stage renal disease: can dietary protein restriction prevent it?

The hypothesis that dietary protein restriction slows the rate of progression of chronic renal disease has been tested in four large clinical trials, the largest and most elegant of which was the Modification of Diet in Renal Disease (MDRD) study conducted recently in the United States. During these trials the majority of patients with nondiabetic renal disease had slow progression, and no overall benefit from dietary intervention was demonstrated in three of four studies. However, MDRD is the first trial to suggest that protein restriction has a two-stage effect on renal function. During the first 4 months, glomerular filtration rate (GFR) fell more rapidly in patients with protein restriction than in patients with normal protein intake, probably because of a hemodynamic effect on the renal microcirculation. After this 4-month period, the rate of decline in GFR was slower in patients on the low protein diet. This suggests but does not prove that low protein diet may slow progression of renal disease in the long run. MDRD also showed that strict control of hypertension slows progression in patients with heavy proteinuria.