Comparison of the effects of keto acid analogues and essential amino acids on nitrogen homeostasis in uremic patients on moderately protein-restricted diets

Abstract

Comparisons of isonitrogenous supplements (1.2 g N) of essential amino acids and five keto acid analogues with four essential amino acids were made in seven patients with stable chronic renal failure (creatinine clearance, 4.6 to 16 ml/min) on moderately protein-restricted diets (4.60 to 7.8 g N per day). Full nitrogen balance data on the four patients who have already completed studies lasting 24 weeks are presented. No benefits of keto acid over amino acid supplements were observed. Two transient episodes of hypercalcemia occurred during keto acid treatment. There was no improvement of renal function with keto acids. Also, no carry-over effects were seen after keto acid treatment. It is concluded that any beneficial effects of keto acids in patients with chronic renal failure are only likely to occur in those taking a diet of less than 30 g protein daily.

Dietary Management of Chronic Renal Failure with Oral Amino Acids

“…Our studies, in common with many others, confirm that low protein diets do not arrest the rate of progression of chronic renal failure per se. Since there are considerable reservations about the nutritional significance of so-called urea nitrogen recycling and since both a-keto acids and a-hydroxy acid analogues of amino acids provide manufacturing and cost difficulties, and since also their effectiveness has not been confirmed (Burns et al, 1978), the amino acid preparations seem to hold some advantages and represent the most useful and safe dietary adjunct.…”

“…Thus by ensuring the provision of the minimal daily essential amino acid requirements for these patients, more flexibility has been allowed with dietary protein choice and improved palatability has followed. Since there is little evidence to suggest that the more expensive keto acid dietary supplements, which are of debatable efficacy, are better than the amino acid supplements (Burns et al, 1978;Richards, 1978;Editorial, 1978), the latter seems worthy of further considera tion.…”

Blood levels of branched-chain ?-keto acids in uremia: Therapeutic implications

“…Serum measurements of BCKA's may also help to decide as to whether therapy with keto acids should be promoted with more [12] or less [3] enthusiasm.…”

Amino Acids and Keto Acids in the Treatment of Chronic Renal Failure

“…In addition, a marked decrease in the circulating level of parathyroid hormone was reported by sev eral groups [58][59][60]. In only two studies there was no apparent benefit of adding a KA (or AA) mixture: as mentioned above, these patients received a protein intake in excess of 40 g/day [44,45].…”

“…KAs are oxidized and eliminated without further urea generation, but without benefit for the patient. This was demonstrated to occur in patients eating a diet containing 7-9 g N/day, i.e., more than 40 g proteins for 70 kg body weight [44,45], probably due to the more rapid oxidation of KAs that occurs when protein intake increases. Reciprocally, the rate of transamination of ketovaline and of ketoleucine increases when protein supply is reduced [46].…”