Update on branched-chain amino acid supplementation in liver diseases

Abstract Purpose of review Branched-chain amino acids (BCAAs) have a peculiar role in whole-body nitrogen metabolism. BCAAs are a substrate for protein synthesis, and have been used to conserve or restore muscle mass in advanced liver disease. In addition, the competitive action of BCAAs on amino acid transport across the blood-brain barrier may improve hepatic encephalopathy. Recent findings The effects of BCAAs on nutrition and ultimately on prognosis of patients with advanced cirrhosis have been confirmed in a large multicenter, long-term trial. Similarly, BCAA treatment improved the prognosis of patients with hepatocellular carcinoma, treated by chemoembolization. The mechanism for the beneficial effects of BCAA is likely to depend on the stimulating activity of BCAA on hepatocyte growth factor, favoring liver regeneration. Summary After an experience of 25 years with BCAAs, new data supports their beneficial effect in liver diseases. Although the number of patients who cannot tolerate dietary proteins in amounts sufficient to meet their increased catabolism is probably low, in this specific setting BCAAs remains the sole treatment of proved efficacy

Update on nutritional supplementation with branched-chain amino acids

Abstract Purpose of review Branched-chain amino acids BCAAs have a peculiar role in whole-body nitrogen metabolism. BCAAs are not only a substrate for protein synthesis, but also modulate several components of the synthetic machinery and help to conserve muscle mass; accordingly several conditions, characterized by protein loss and catabolic status, are likely to benefit from amino acid administration. In addition, the competitive action of BCAAs on amino acid transport across the blood-brain barrier may ultimately alter the synthesis of brain neurotransmitters, involved in neurological diseases. Recent findings Both putative actions of BCAAs have been tested in controlled clinical studies in the last few years. The beneficial effects on nutrition were reported to improve muscle performance, to reduce protein loss during bed-rest, to favor weight loss in obesity, to reduce catabolism in trauma patients, and improve clinical outcomes in patients with advanced cirrhosis. In this last area the effects on nutrition might be coupled with the effects on hepatic encephalopathy mediated by improved neurotransmission, successfully tested in mania, in tardive dyskinesia and spinocerebellar degeneration. Summary After 30-years of investigation with BCAAs, new studies each year provide further evidence supporting their beneficial effect in a variety of diseases. There is a need for long-term, randomized clinical studies, both in the prevention and in the treatment of various pathological conditions