Liver disease, in one typical example, develops and progresses as follows: (1) acute hepatitis develops mainly due to viral infection and drug allergy, (2) the acute hepatitis transitions to chronic hepatitis, and (3) the chronic hepatitis further progresses and transitions to liver cirrhosis or liver cancer. It is important to prevent liver diseases from becoming chronic. In addition, patients with alcoholic or non-alcoholic fatty liver associated with lifestyle-related diseases such as obesity and diabetes have been increasing in recent years.
Subjective symptoms are less in an early stage of liver diseases. Particularly, chronic hepatitis and liver cirrhosis are characterized by almost no early symptoms. Therefore, it is important to observe what kind of state the liver is now in by the inspection including blood tests at medical examinations. Aspartate aminotransferase (hereinafter referred to as AST) and alanine aminotransferase (hereinafter referred to as ALT) are each a test item that is most basic in a liver function test. Both AST and ALT are enzymes that are present in the organ cells and catalyze the transamination of amino acids. When the hepatocytes are destroyed due to damages such as inflammation, AST and ALT in the cells flow out into the blood, and blood levels of these escaped enzymes elevate. A normal value of blood AST is 12 to 40 IU/L and a normal value of blood ALT is 5 to 40 IU/L. In contrast, the blood ALT value in a patient with acute hepatocyte disorder may be 500 IU/L or more.
Fatty liver is a disease in which neutral fat accumulates in hepatocytes. When hepatocytes of a patient with fatty liver are viewed under a microscope, vacuoles containing fat droplets are observed. In many cases, AST value and ALT value of fatty liver patients are slightly higher than the normal values (2 to 4 times the normal value, or less). Fatty liver includes simple steatosis and steatohepatitis accompanied with fibrosis of the hepatocytes. It is often the case that an AST value and an ALT value in the steatohepatitis are high in comparison with those in simple steatosis.
Blood AST and ALT values are important indicators in the inspection of liver dysfunction, and an improvement of AST value and ALT value is needed in the prevention and treatment of various liver diseases.
Various medicaments for the prevention or improvement of liver dysfunction are known. As a medicament for the prophylaxis or treatment of viral hepatic disease, a therapeutic agent for hepatitis B or hepatitis C is known in addition to hepatitis virus vaccines. Known liver function-improving agents derived from natural products include an extract from cortex of Mallotus japonicus (Patent Document 1), lactoperoxidase (Patent Document 2), S2U type triglyceride (Patent Document 3), glutathione and turmeric (Curcuma longa) (Patent Document 4), isomaltulose (Patent Document 5), and Japanese apricot extract or a neutralization product of Japanese apricot extract for patients with viral hepatitis (Patent Document 6).
Insulin sensitizers, therapeutic agents for dyslipidemia, medicaments for liver, and angiotensin II1 receptor antagonists have been reported as effective for inhibiting fat accumulation in the liver (Non-Patent Document 1). Known agents which are derived from natural products and prevent fat accumulation in the liver include a high polymer polysaccharide substance MPS-80 (Patent Document 7), a hemicellulose obtained from corn bran and/or partially degraded product thereof for patients with alcoholic liver disease (Patent Document 8), a polysaccharide having a molecular weight of 400,000 or more derived from tea (Patent Document 9), a culture and/or bacterial cells of lactic acid bacteria belonging to Lactobacillus gasseri (Patent Document 10), olive or an extract thereof (Patent Document 11), barley bran or Cc-amylase treated product thereof (Patent Document 12), and bacterial cells of Lactobacillus helveticus (Patent Document 13).