What Is Bile?

A digestive fluid produced by the liver that breaks down fats.

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Bile, also known as gall, is a yellow-green, thick, sticky fluid that is made by the liver and helps with digestion of fats. It breaks down fats into fatty acids, which can be taken into the body by the digestive tract.

Bile's other important functions include getting rid of certain waste products from the body, such as hemoglobin from destroyed red blood cells and excess cholesterol.

An illustration of the liver in the body
SEBASTIAN KAULITZKI / SCIENCE PHOTO LIBRARY / Getty Images

Bile

A digestive fluid produced by the liver and stored in the gallbladder that breaks down fats in the small intestine and helps remove wastes from the body.

Makeup

Many compounds make up bile, but one of the most important ones are bile acids, also known as bile salts, that emulsify fats during digestion and assist in their absorption.

Bile contains:

  • Bile acids
  • Cholesterol
  • Water
  • Pigments, including bilirubin
  • Phospholipids (complex fats that contain phosphorus)
  • Electrolytes, including sodium and potassium
  • Metals, such as copper

The main pigment in bile, bilirubin, is responsible for jaundice when it accumulates in the blood and body tissues. Bilirubin is a waste product of hemoglobin, which carries oxygen in blood, and its secretion into bile helps remove it from the body by passing it through the digestive system and then out of the body in feces.

Function

Bile plays a key role in digestion of fats so they can be used by the body and in removal of metabolic wastes that cannot be used by the body.

Its three main functions are:

  • Helps break down fats into forms that can be absorbed
  • Assists in absorption of fat-soluble vitamins
  • Helps remove metabolic waste, including bilirubin and cholesterol, and toxins

By breaking down fats, bile acids are also crucial in intestinal absorption of the fat-soluble vitamins A, D, E, and K.

Where It's Found

The liver produces about 800 to 1,000 milliliters (27 to 34 fluid ounces) of bile each day. The liver is an important organ of the body that is responsible for detoxification, metabolism, synthesis, and storage of various substances. 

The liver is crucial to life. Without it, a person couldn't live for more than 24 hours. 

Bile is secreted by the liver and stored in the gallbladder, a sort of storage sac organ attached to the underside of the liver.

During meals, bile is released from the gallbladder through a tube called the common bile duct. The duct connects your gallbladder and liver to your duodenum, the first part of your small intestine.

Discovery

An understanding of bile dates back to antiquity, yet the first bile acid wasn't documented until 1848. It wasn't until the 1920s that there was a more thorough study of the chemistry and biology of bile.

German scientist Heinrich Weiland won a Nobel Prize in chemistry in 1928 for revealing the composition of bile acids and helping to clarify their function.

Novel Bile Acids

Discoveries related to bile are ongoing. Research published in 2020 in the journal Nature documented the finding of novel bile acids made by microbes in the gut of both mice and humans.

More research is needed to confirm the findings, but the study suggests that that the gut microbiome may also play a role in production of bile acids in addition to enzymes in the liver.

How It Works

Between meals, bile is stored in the gallbladder, and only a small amount of bile flows into the intestine. Bile also becomes more concentrated during the storage process.

Fatty foods that enters the duodenum prompts hormonal and nerve signals that cause the gallbladder to contract. The hormones that control this process are:

  • Cholecystokinin
  • Secretin
  • Gastrin
  • Somatostatin 

Signals also come from the vagus nerve.

As a result, bile flows into the duodenum and mixes with food and your stomach acids and digestive fluids from the pancreas, which helps the intestines absorb nutrients into your bloodstream.

In the lower part of the small intestine, most of the bile acids are absorbed and circulated into the bloodstream and back to the liver.

Associated Conditions

There are many conditions that can lead to cholestasis, which is the reduction or blockage of bile flow. This includes disorders of the liver, pancreas, or gallbladder or any damage to bile ducts.

Conditions that can scar or inflame the liver and can lead to cholestasis include:

Bile duct damage is generally considered a symptom of chronic hepatitis C. Hepatitis C and other types of viral hepatitis can impact the liver’s ability to produce bile, which can result in a host of digestive issues and, ultimately, inflammation of the gallbladder.

But hepatitis isn't the only disease that can impact bile production and the gallbladder. Other conditions that can affect bile production and/or movement include:

When bile flow is reduced or stopped, bilirubin can accumulate in the bloodstream and lead to jaundice. Symptoms of jaundice may include a yellowing of the skin and eyes and dark urine.

Your gallbladder is most likely to give you trouble if something, like a gallstone, blocks the flow of bile through the bile ducts. Treatment may include cholecystectomy, a surgical removal of the gallbladder.

In cases where the gallbladder is removed, bile gets transferred directly from the liver to the small intestine. The gallbladder is not essential to the process.

Obstruction of the bile ducts, from either gallstones or gallbladder cancer, can actually mimic acute viral hepatitis. That said, ultrasound diagnostics can be used to rule out the possibility of gallstones or cancer.

An additional condition related to bile is bile reflux. It occurs when bile backs up (refluxes) into your stomach and the tube that connects your mouth and stomach (esophagus). Bile reflux sometimes happens along with acid reflux (backwash of stomach acids into your esophagus).

Unlike acid reflux, dietary or lifestyle changes don't usually improve bile reflux. Treatment involves medications or, in severe cases, surgery.

A Word From Verywell

Bile plays a powerful role in digestion and we are still learning about its production and cycle through the gut.

If you have a jaundice or have been diagnosed with a condition that affects the production or flow of bile, it's important to remember that there are many treatment options that can help to restore or improve the flow of bile and any associated digestive issues you may be experiencing.

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