Recommendations for consuming protein are particularly confusing for patients with kidney failure, as these guidelines change during the course of the disease. These guidelines get even more confusing with respect to particular amino acids. Additional research is needed to determine whether supplementation with essential amino acids would provide any benefit to these patients.
Definitions
The term "kidney failure" includes all stages of kidney disease, including early stages in which the only symptoms may be edema and hypertension. These early stages are also often described as "renal insufficiency" rather than kidney failure. Kidney failure also includes end-stage renal disease, also known as ESKD. A patient who reaches ESKD needs dialysis or transplant to stay alive.
Proteins are made from 20 different amino acids. The body makes many of these, but according to MedlinePlus, nine must be supplied from dietary sources. These nine amino acids are called essential amino acids.
Early Stages
Patients in the early stages of kidney failure often have very high urine protein. The National Kidney Foundation recommends that these patients limit protein consumption to 0.8 g per kilogram of body weight. The focus for these patients is not on limiting consumption of specific essential amino acids; rather, the focus is on limiting total protein intake. There is no evidence that any specific amino acid is more damaging than any other.
Dialysis
Dietary requirements change if patients reach ESKD and start dialysis. Unlike patients in the early stages of kidney failure, these patients need all the protein they can get to prevent the muscle wasting that often dogs them. An article in the January 2009 issue of Seminars in Nephrology reports that approximately one third of dialysis patients have a poor appetite, which is directly related to morbidity and mortality.
Supplementation
In addition to appetite issues, dialysis patients struggle with getting enough protein because amino acids get filtered from the blood. No study shows that essential amino acids are anymore affected than other amino acids. Rather than focusing upon essential amino acids, patients are advised to increase protein consumption in general. This is true for nonessential amino acids as well. For example, the nonessential amino acid carnitine is particularly affected by dialysis. The National Kidney Foundation reports that carnitine levels are low in both adults and children on dialysis. However, there is insufficient data that suggests carnitine supplementation is beneficial.
References
- "Seminars in Dialysis"; Dietary Protein Intake in Patients with Advanced CKD; R. Dukkipati; et al.; July-August, 2010
- "American Journal of Kidney Disease?"; Why Are Dialysis Patients Malnourished?; J. Bergström; July, 1995
- "Renal Failure"; A Novel Amino Acids Oral Supplementation in HD Patients; P. Bolasc; 2011
- "Seminars in Nephrology;" Why Are Chronic Kidney Disease Patients Anorexic?; C. Chazot; January, 2009
- MedlinePlus: Kidney Failure
- MedlinePlus: Amino Acids
