During
renal failure, abnormalities of BCAA and branched-chain keto
acid (BCKA) metabolism are due to both the lack of renal contribution to
amino acid metabolism and the impact of
renal failure and
acidosis on whole-body
nitrogen metabolism. Abnormal BCAA and BCKA metabolism result in BCAA depletion as reflected by low plasma BCAAs and cellular
valine. BCAA metabolic disturbances can alter tissue activities, particularly brain function, and nutritional status. In dialysis patients, BCAA oral supplementation can induce an improvement of appetite and nutritional status. During
chronic renal failure, the aims of nutritional interventions are to minimize uremic toxicity, avoid
malnutrition and delay progression of
kidney disease. BCAA and BCKA supplements have been proposed to decrease further
protein intake while maintaining satisfactory nutritional status. In this setting, BCAAs or BCKAs have not been administrated solely but in association with other essential AA or keto analogs. Therefore, the proper effects of BCAAs and/or BCKAs have not been studied separately.
Protein restriction together with
keto acids and/or essential AAs has been reported to improve
insulin sensitivity and
hyperparathyroidism and to be compatible with a preservation of nutritional status. Nonetheless, a careful monitoring of
protein-calorie intake and nutritional status is needed. A recent meta-analysis concluded that reducing
protein intake in patients with
chronic renal failure reduces the occurrence of renal death by approximately 40% as compared with larger or unrestricted
protein intake. The additional effect of
essential amino acids and
keto acids on retardation of progression of
renal failure has not been demonstrated.