Controlled trials on low-protein diet: effects on chronic renal insufficiency progression

The effect of a low-protein diet (LPD) on chronic renal insufficiency (CRI) progression was investigated by reviewing the published studies. Only three of these fulfilled the main methodological criteria of being randomized, prospective, and controlled: those of Rosman, Ihle and Locatelli. These trials involved 811 patients (671 evaluated: 338 on a LPD, 333 as controls) and had a mean follow-up of 29 months (range 18-48), for an estimated total of about 17,335 patient-months. The only trial whose results showed that LPD had a positive effect on chronic renal failure (CRF) progression was Ihle's study, with the lowest weight (6.7%) and involving the most severe CRF; effects limited to the patients with more advanced CRF were found in the Rosman study, with an intermediate weight (41.8%); and little effect, if any, was found in the Locatelli trial, accounting for 51.5% of patient-months, with less severe CRI. In conclusion, analysis of published randomized, prospective, and controlled trials offers little or no support for the hypothesis that a LPD has a clinically significant effect on the early CRI progression, although a very low protein diet seems to postpone the need for dialysis.