Effect of low-protein diet on renal function: are there definite conclusions from adult studies?

Low-protein diets have been used for roughly a century in order to alleviate uraemic symptoms and to delay progression of chronic renal failure (CRF). Currently a number of different low-protein diets are used, supplying either 0.6 g protein/kg body weight or 0.3-0.4 g supplemented with amino-acids or keto-acids. Single centre trials have attempted to demonstrate the efficacy of these diets in slowing down the progression of CRF. The results from these trials are, however, sometimes inconclusive, showing either a high efficiency of the low-protein diet or no efficiency at all. Conclusive data from multicentre trials, however, are not yet available. A crucial point in analysing the efficacy of low-protein diets is the degree of compliance with the protein restriction. Today, the data available indicate that sometimes only a poor degree of compliance is achieved both in single and in multicentre trials.

Does a low protein diet really slow down the rate of progression of chronic renal failure?

In this paper we present evidence from data obtained by different study groups, indicating that a low protein diet slows down the rate of progression of chronic renal failure. These data also demonstrate that the delay of progression is highly dependent on the underlying renal disease. In absolute terms, patients suffering from polycystic kidney disease experienced most benefit from a low protein diet, while in relative terms, the natural course of the renal disease of patients suffering from chronic glomerulonephritis is significantly more delayed than in other disease groups. Furthermore, a vegetarian diet seems to be superior to a meat-containing diet. Thus, we conclude that there are sufficient data from the literature to suggest that a low protein diet delays the progression of chronic renal failure.

Controlled trial of two keto acid supplements on renal function, nutritional status, and bone metabolism in uremic patients.

In this matched, controlled study, two different types of EAA/KA supplements were compared in uremic patients fed a 30 g protein restricted diet. The patients were paired for age, sex, and underlying renal disease. The supplement with the higher BCKA content resulted in an improvement of renal function, bone metabolism, and a normalization of plasma BCAA concentrations. With both supplements, adequate nutritional status of the patients was maintained. We conclude that the BCKA content of the supplement is of considerable importance for uremic patients on low protein diets.

The influence of two different essential amino acid/keto analogue preparations on the clinical status of patients with chronic renal failure.

58 outpatients with a serum creatinine between 6-10 mg/dl received a low protein diet (LPD) with 30 g protein/day, supplemented with essential amino acids (EAA) or their keto analogues (KA). Group A (n = 19) was given an EAA/KA supplement according to the pattern proposed by Rose and group B (n = 39) received a preparation with an increased amount of KAs of branched chain amino acids (BCKA), as recommended by Walser. At the start of treatment with a LPD supplemented with either of the two supplements and after 6 months of treatment we assessed: plasma branched chain amino acids (BCAA), renal function, nutritional status, and bone metabolism. After six months of dietary treatment the results showed in group B in contrast to group A an improvement of nutritional status (body weight increased, urea decreased, and BCAA normalized). The same was true for bone metabolism (significantly lower phosphate levels, increased calcium values). In both groups progression of chronic renal failure slowed down, but the delay was more pronounced in group B. All results were statistically significant (p less than 0.01).