Supplemental Low-Protein Diet in Chronic Renal Failure

To the Editor: Mitch et al. reported retardation of the progression of renal insufficiency after administration of a protein-restricted diet supplemented with a keto acid–amino acid mixture (Sept. 6 issue).¹ For evaluation of the data, however, more information would be appreciated about possible confounding variables that may influence the progression of renal insufficiency or the time course of serum creatinine concentrations. This caveat is particularly important since no control group was included.¹ As one example, other investigators have reported that lowering of high blood pressure may retard the progression of renal failure, at least in Type I diabetes.² It is.