Liver and metabolism
Understanding the role of the liver in digestive health
The liver is the body’s main processing organ. It makes bile, which is needed to digest fat. It receives all the blood leaving the intestine and processes the nutrients in it, stores energy and vitamins, makes essential proteins, and clears alcohol, medicines and waste. Liver disease is often silent for years, which is why simple checks and a few protective habits matter.
In short
- The liver has hundreds of functions. Digestion depends on its bile and on its handling of absorbed nutrients.
- It has a large reserve and can regenerate, so symptoms appear late.
- The commonest liver conditions in India are fatty liver, alcohol-related disease and hepatitis B and C.
- The liver clears waste without help from special diets or products.
What does the liver do for digestion?
Makes bile
More than half a litre a day. Bile breaks fat into small droplets so that enzymes can digest it, and it is needed to absorb vitamins A, D, E and K.
Processes nutrients
Blood from the intestine flows to the liver first. The liver stores sugar as glycogen and releases it between meals, builds proteins from amino acids, and packages fats for transport.
Stores reserves
Iron, vitamin B12, vitamin A and vitamin D are held in the liver.
Clears waste and foreign substances
It converts alcohol, medicines and the by-products of metabolism into forms that leave the body in bile or urine.
Makes essential proteins
Including albumin, which holds fluid in the blood vessels, and the factors that make blood clot.
How do the liver, gallbladder and gut work together?
Bile flows from the liver into the bile ducts. Between meals it is stored and concentrated in the gallbladder. When food containing fat arrives in the small intestine, the gallbladder contracts and releases bile. Most bile acids are reabsorbed at the end of the small intestine and returned to the liver to be used again.
When this system fails, the results are familiar: gallstones form in the gallbladder, and blocked bile flow causes jaundice, pale stools and itching.
What are the signs of liver trouble?
Early liver disease usually causes none. Later signs include:
- Tiredness and poor appetite
- Yellow eyes and skin, dark urine, pale stools
- Itching without a rash
- Swelling of the legs or abdomen
- Easy bruising
- Confusion, or sleeping by day and lying awake at night
See a doctor promptly for
Yellow eyes, a swollen abdomen, vomiting of blood, black stools or new confusion.
What are the common liver conditions?
| Condition | Main cause |
|---|---|
| Fatty liver (MASLD) | Weight around the waist, diabetes, diet high in sugar |
| Alcohol-related liver disease | Regular or heavy drinking |
| Hepatitis B and C | Viruses spread through blood and body fluids |
| Hepatitis A and E | Viruses spread through contaminated water and food |
| Injury from medicines and herbal products | Certain medicines in excess; some herbal and bodybuilding supplements |
| Cirrhosis | Long-standing damage from any of the above |
How is the liver checked?
- Liver blood tests: enzymes that rise when liver cells are injured, bilirubin, albumin and clotting time
- Tests for hepatitis B and C
- Ultrasound: shows fat, the size and outline of the liver, the bile ducts and gallstones
- FibroScan: measures stiffness, which reflects scarring
Normal liver enzymes do not exclude fatty liver or scarring, which is why a scan or a risk score is used when there are risk factors.
How do I protect my liver?
Keep weight around the waist down
With regular exercise and less sugar and refined carbohydrate.
Limit or avoid alcohol
There is no amount that is good for the liver.
Get vaccinated
Against hepatitis B, and hepatitis A where advised.
Be careful with medicines and supplements
Do not exceed the stated dose of paracetamol. Avoid herbal products of unknown composition. Tell your doctor about everything you take.
Avoid unsafe needles
Insist on sterile, single-use needles for injections, tattoos and piercings.
Drink clean water
Hepatitis A and E spread through contaminated water.
Coffee without sugar is linked with a lower risk of liver scarring.
Does the liver need cleansing?
No. The liver clears waste continuously. No juice, tea or supplement has been shown to help it do so, and several herbal “liver” products have caused liver injury. See prebiotics and the facts about such products.
Questions patients ask me
Can the liver repair itself?
Yes, to a remarkable degree. It regenerates after injury, and fat and early scarring improve when the cause is removed. Advanced scarring does not fully heal.
My liver enzymes are slightly raised. Should I worry?
Mild rises are common and are most often due to fatty liver, alcohol or a medicine. They should be explained, not ignored. A repeat test, an ultrasound and tests for hepatitis are the usual next steps.
Is fatty food bad for the liver?
Sugar and refined carbohydrate drive liver fat more than dietary fat does. Fried and processed foods add to weight gain, which matters too.
Who should be tested for hepatitis B and C?
Anyone with raised liver enzymes, a family member with the infection, a past blood transfusion or surgery, or planned pregnancy. Many doctors advise one test for every adult.
Sources
This page is written for patients and is based on the guidelines and studies below. It is for education and does not replace a consultation.
- American Association for the Study of Liver Diseases practice guidance on fatty liver disease. Rinella ME et al. Hepatology. 2023. PubMed 36727674
- European guideline on metabolic dysfunction-associated steatotic liver disease (MASLD). EASL, EASD, EASO. J Hepatol. 2024. PubMed 38851997
- European Association for the Study of the Liver guideline on gallstones. EASL. J Hepatol. 2016. PubMed 27085810
- Review of the gut-liver axis and the microbiome. Tripathi A et al. Nat Rev Gastroenterol Hepatol. 2018. PubMed 29748586