The liver is the largest solid organ and the largest gland in the human body. It carries out over 500 essential tasks.

Classed as part of the digestive system, the roles of the liver include detoxification, protein synthesis, and the production of chemicals that help digest food.

This MNT Knowledge Center article will cover the main roles of the liver, how the liver regenerates, what happens when the liver does not function correctly, and how to keep the liver healthy.

Fast facts on the liver

  • The liver is classed as a gland.
  • This vital organ carries out more than 500 roles in the human body.
  • It is the only organ that can regenerate.
  • The liver is the largest solid organ in the body.
  • Alcohol abuse is one of the major causes of liver problems in the industrialized world.

The liver is classed as a gland and associated with many functions. It is difficult to give a precise number, as the organ is still being explored, but it is thought that the liver carries out 500 distinct roles.

The major functions of the liver include:

  • Bile production: Bile helps the small intestine , cholesterol, and some vitamins. Bile consists of bile salts, cholesterol, bilirubin, electrolytes, and water.
  • Absorbing and metabolizing bilirubin: Bilirubin is formed by the breakdown of hemoglobin. The iron released from hemoglobin is stored in the liver or bone marrow and used to make the next generation of blood cells.
  • Supporting blood clots: Vitamin K is necessary for the creation of certain coagulants that help clot the blood. Bile is and is created in the liver. If the liver does not produce enough bile, clotting factors cannot be produced.
  • Fat metabolization: Bile breaks down fats and makes them easier to digest.
  • Metabolizing carbohydrates: Carbohydrates are stored in the liver, where they are broken down into glucose and siphoned into the bloodstream to maintain normal glucose levels. They are stored as glycogen and released whenever a quick burst of energy is needed.
  • Vitamin and mineral storage: The liver stores vitamins A, D, E, K, and B12. It keeps significant amounts of these vitamins stored. In some cases, several years' worth of vitamins is held as a backup. The liver stores iron from hemoglobin in the form of ferritin, ready to make new red blood cells. The liver also stores and releases copper.
  • Helps metabolize proteins: Bile helps break down proteins for digestion.
  • Filters the blood: The liver filters and removes compounds from the body, including hormones, such as estrogen and aldosterone, and compounds from outside the body, including alcohol and other drugs.
  • Immunological function: The liver is part of the mononuclear phagocyte system. It contains high numbers of Kupffer cells that are involved in immune activity. These cells that might enter the liver through the gut.
  • Production of albumin: Albumin is the most common protein in blood serum. It transports fatty acids and steroid hormones to help maintain the correct pressure and prevent the leaking of blood vessels.
  • Synthesis of angiotensinogen: This hormone raises blood pressure by narrowing the blood vessels when alerted by production of an enzyme called renin in the kidneys.

There is a range of conditions that affect the liver.

An organ as complex as the liver can experience a range of problems. A healthy liver functions very efficiently. However, in a diseased or malfunctioning liver, the consequences can be dangerous or even fatal.

Examples of liver disease include:

Fascioliasis: This is caused by the parasitic invasion of a parasitic worm known as a liver fluke, which can lie dormant in the liver for months or even years. Fascioliasis is considered a tropical disease.

Cirrhosis: This sees scar tissue replace liver cells in a process known as fibrosis. This condition can be caused by a number of factors, including toxins, alcohol, and hepatitis. Eventually, fibrosis can lead to liver failure as the functionality of the liver cells is destroyed.

Hepatitis: Hepatitis is the name given to a general infection of the liver, and viruses, toxins, or an autoimmune response can cause it. It is characterized by an inflamed liver. In many cases, the liver can heal itself, but liver failure can occur in severe cases.

Alcoholic liver disease: Drinking too much alcohol over long periods of time can cause liver damage. It is the cause of cirrhosis in the world.

Primary sclerosing cholangitis (PSC): PSC is a serious inflammatory disease of the bile ducts that results in their destruction. There is currently no cure, and the cause is currently unknown, although the condition is thought to be autoimmune.

Fatty liver disease: This usually occurs alongside obesity or alcohol abuse. In fatty liver disease, vacuoles of fat build up in the liver cells. If it is not caused by alcohol abuse, the condition is called non-alcoholic fatty liver disease (NAFLD).

It is usually caused by genetics, medications, or a diet high in fructose sugar. It is the most common liver disorder in developed countries and has been associated with insulin resistance. Non-alcoholic steatohepatitis (NASH) is a condition that can develop if NAFLD gets worse. NASH is a known cause of liver cirrhosis.

Gilbert's syndrome: This is a genetic disorder affecting of the population. Bilirubin is not fully broken down. Mild jaundice can occur, but the disorder is harmless.

Liver cancer: The most common types of liver cancer are hepatocellular carcinoma and cholangiocarcinoma. The leading causes are alcohol and hepatitis. It is the form of cancer and the second most frequent cause of cancer death.

Below are some to help keep your liver working as it should:

Despite its ability to regenerate, the liver depends on being healthy to do so. The liver can mostly be protected through lifestyle choices and dietary measures.