Therapeutic Effects of Amino Acids in Liver Diseases: Current Studies and Future Perspectives

Hepatocellular carcinoma (HCC) is the most common primary malignant tumor of the liver and the third most common cause of cancer-related death worldwide. HCC is caused by infection of hepatitis B/C virus and liver dysfunctions, such as alcoholic liver disease, nonalcoholic fatty liver disease, and cirrhosis. Amino acids are organic substances containing amine and carboxylic acid functional groups. There are over 700 kinds of amino acids in nature, but only about 20 of them are used to synthesize proteins in cells. Liver is an important organ for protein synthesis, degradation and detoxification as well as amino acid metabolism. In the liver, there are abundant non-essential amino acids, such as alanine, aspartate, glutamate, glycine, and serine and essential amino acids, such as histidine and threonine. These amino acids are involved in various cellular metabolisms, the synthesis of lipids and nucleotides as well as detoxification reactions. Understanding the role of amino acids in the pathogenesis of liver and the effects of amino acid intake on liver disease can be a promising strategy for the prevention and treatment of liver disease. In this review, we describe the biochemical properties and functions of amino acids and to review how they have been applied to treatment of liver diseases.