The liver, which is located just behind the right side of the rib cage, is the largest internal organ in the human body, accounting for about one-fiftieth of body weight. It has three main functions. Firstly, it synthesizes proteins needed by the body and stores nutrients. Secondly, it detoxifies and decomposes harmful substances. Thirdly, it synthesizes and secretes the bile necessary for food digestion.

When food is eaten it is broken down in the stomach and intestines, and then sent to the liver. Here, it is processed and converted into various components, before being delivered through the arteries to where it is needed in the body. For example, sugar from meals is stored in the liver as glycogen and released into the blood as an energy source at night. Waste products that are no longer needed after being used are returned through the veins to the liver and excreted in the bile. Some of this is reabsorbed by the small intestine and reused in the liver. In this way, the liver is a factory fully equipped for production and recycling.

There are both acute and chronic diseases of the liver; special care must be taken with chronic liver disease.

Hepatitis C is common among Japanese people. In the process of attempting to rid the body of the virus, immune cells such as lymphocytes damage not only the virus, but the liver cells too, resulting in inflammation.

Chronic hepatitis is a state in which this mild inflammation lasts for more than six months.

When the body is unable to keep up with the reconstruction of the hepatocytes (liver cells) that have been damaged by the inflammation, it can lead to liver cirrhosis or liver cancer.

Excessive drinking or eating can also lead to neutral fat accumulation, causing fatty liver disease.

It is known that in some cases fatty liver disease causes chronic inflammation, and may progress to liver cirrhosis.