What Is Bile?

Bile is a sticky, yellow-green digestive fluid made by the liver. Its main job is to break down fats into fatty acids so that they can be absorbed by your body through the digestive tract. Bile is stored in the gallbladder and is sometimes also called gall.

Bile also gets rid of certain waste products from your body, such as hemoglobin, a protein that comes from destroyed red blood cells and excess cholesterol.

This article discusses the various functions of bile in your body—how it's made, what it does, and why your body needs it. Further down, you will also find information about bile-related medical conditions, some of which can be life-threatening.

What Bile Is Made Of

Many compounds make up bile, but one of the most important ones are bile acids—also known as bile salts, which blend fats together during digestion so that your body can absorb them.

Bile is made of the following components:

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

Bilirubin is a waste product of hemoglobin that carries oxygen in the blood. Bilirubin is secreted into bile so that it can pass through the digestive system then leave the body in feces.

What Bile Does

Bile plays a key role in digesting fats so that they can be used by the body. Bile is also necessary for removing what the body cannot use.

Bile serves three main functions:

• It helps break down fats into forms that can be absorbed
• It helps absorb fat-soluble vitamins
• It helps remove toxins and metabolic waste, including bilirubin and cholesterol

By breaking down fats, bile acids also help your intestines absorb the fat-soluble vitamins A, D, E, and K.

Where Bile Is Found

The liver filters, breaks down, converts, and stores various substances so that your body can use or remove them.

The liver also produces about 800 to 1,000 milliliters (27 to 34 fluid ounces) of bile each day. Bile is secreted by the liver and stored in the gallbladder, a small organ attached to the underside of the liver.

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

Discovery

Humans have wondered about bile for ages, but it wasn't until 1848 that theories about bile were first documented. Fast forward to the 1920s when scientists began to study the chemistry and biology of bile in detail.

In 1928, a German scientist named Heinrich Weiland won a Nobel Prize in chemistry for revealing the composition of bile acids. His discovery helped clarify the important functions of bile acids in the body.

Discoveries related to bile are ongoing. Research published in 2020 in the journal Nature documented the finding that novel bile acids are made by microbes in the gut.

More research is needed to confirm the findings, but the study suggests that the gut microbiome—bacteria and other microbes that live in your gastrointestinal tract—may play a role in producing both bile acids and enzymes in the liver.

How Bile 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 this storage process.

Fatty foods that enters the duodenum prompt 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, which extends from the brainstem all the way down to your abdomen.

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

Most of the bile acids are absorbed through the lower intestine then circulated into the bloodstream and back to the liver.

Associated Conditions

Many people are familiar with jaundice, when bilirubin (the main pigment in bile) accumulates in the bloodstream. It is common in newborns, who are not always developed enough to remove the pigment from their system. Classic signs include dark urine and yellowing of the skin and eyes.

But jaundice can also occur in people of all ages when bile flow from the liver to the duodenum slows or stops for another reason. Known as cholestasis, this can occur as a result of liver, pancreas, or gallbladder disorders, or any damage to bile ducts.

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

• Hepatitis
• Cirrhosis
• Primary sclerosing cholangitis (PSC)
• Alcohol-related liver disease (ALRD)
• Liver cancer

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, gallbladder inflammation.

Other conditions that can affect bile production or flow include:

• Gallstones
• Gallbladder, bile duct, or pancreatic cancer
• Pancreatitis
  

Your gallbladder is most likely to give you trouble if something like a gallstone blocks bile from flowing through the bile ducts. Treatment may include cholecystectomy, which is surgery to remove the gallbladder. After this procedure, bile gets transferred directly from the liver to the small intestine. The gallbladder is not essential to the process.

Bile duct obstruction, due to gallstones or gallbladder cancer, can actually mimic acute viral hepatitis. Ultrasound can be used to rule out the possibility of gallstones or cancer.

Bile reflux is another related condition. It occurs when bile gets backed up in your stomach and esophagus, the tube that connects your mouth and stomach. Bile reflux sometimes happens along with acid reflux.

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

Summary

Bile is made of several components, including bile acids, bilirubin, and fats. It's made in your liver and stored in your gallbladder until your body needs it for digestion. Bile helps your body separate nutrients it needs from toxins and waste, which are removed in your feces.

If bile flow slows or stops due to disease or inflammation, bilirubin can build up and lead to jaundice. Call your doctor if you notice jaundice, as this is a symptom of gallstones, gallbladder cancer, and other conditions that may require a cholecystectomy.