Plasma amino acid abnormalities in the alcoholic: respective role of alcohol, nutrition, and liver injury.

Plasma amino acid abnormalities are common in alcoholics, but the respective role of alcoholism, nutrition, and liver injury in producing these abnormalities is unknown. To elucidate this question, amino acids were measured in 56 alcoholics and 32 nonalcoholics with liver disease, and in an experimental model of alcoholic liver injury in the baboon. Dietary protein deficiency depressed branched-chain amino acids with a tendency to decreased alpha-amino-n-butyric acid. By contrast, chronic alcoholic consumption selectively increased these amino acids both in short term (2 to 4 weeks) studies in human beings and in 1 to 4-year studies in baboons. Moderate liver injury had no significant effects on these amino acids whereas advanced cirrhosis depressed branched-chain amino acids. Thus, plasma branched-chain amino acids and alpha-amino-n-butyric acid in the alcoholic are affected by at least three variables: dietary protein deficiency and advanced cirrhosis which tend to decrease these amino acids, and chronic alcohol consumption which tends to increase them.