Supplemented low-protein diets: are they superior in chronic renal failure?

Twenty-two patients with chronic renal failure were randomly assigned to a conventional low-protein diet containing 0.6 g protein/kg/day or a very-low-protein diet containing 0.4 g protein/kg/day supplemented with essential amino acids; they were followed up for 9 months. There were no significant changes in body mass index, arm muscle area, percentage body fat, serum albumin and transferrin levels in any of the groups; neither was there any difference between the groups in respect of these parameters. Renal function, as measured by the reciprocal of serum creatinine over time, stabilised in both groups during intervention, with no significant difference between the groups. There was however no correlation between changes in renal function and changes in blood pressure, or dietary intake of protein, phosphorus, cholesterol, polyunsaturated and saturated fatty acids. There were also no significant changes and no significant differences between the groups in serum levels of parathyroid hormone and alkaline phosphatase, urine cyclic adenosine monophosphate, tubular reabsorption of phosphate, and the theoretical renal threshold for phosphate. The results of this study suggest that the supplemented very-low-protein diet was not superior to the conventional low-protein diet in terms of its effect on protein-energy status, renal function and biochemical parameters of renal osteodystrophy.