Your liver is just under three years old — even when you’re 80 — because cells in the organ are constantly renewing themselves, study finds
- German scientists aged the livers of 30 people who were 20 to 84 years old
- Their study is the first time cells in this organ have been aged by scientists
- Bodies replace about one percent of their cells every day, with some such as those in the gut living less than a week while brain cells can live for years
Livers are never older than three years — even when someone reaches their 80s — because the cells are constantly renewing themselves, a study has revealed.
German scientists said their study would help improve understandings of age-related diseases in the organ, such as fatty liver disease and cirrhosis.
It is the first time the cells in this organ — which is the only one capable of regenerating itself when damaged — have been aged by scientists.
Human bodies replace billions of cells every day, with those lining the intestine having the shortest lifespan of just four days. But others like those in muscles can live for 70 years while those in the brain may survive as long as a person lives.
Cells in the liver last for about three years before they are replaced, scientists say. Pictured above is the organ (red area) along with the gall bladder (yellow), which stores bile
In the study, — published earlier this week in the journal Cell Systems — researchers from Dresden University of Technology, 100 miles from Berlin, studied liver samples from 32 patients between 20 and 84 years old.
They had 32 samples from post-mortems for patients that had died, 12 from biopsies and nine that were one type of cell taken from the liver.
To age the sample, the researchers used a method that relies on measuring the amount of carbon in cells from the atmosphere.
What is the liver?
The liver is the largest internal organ in the human body, weighing in at about 3lbs (1.4kg).
It is the main powerhouse with more than 500 functions including producing bile, storing iron and vitamins.
It also cleanses the body from drugs, alcohol and old blood cells.
The organ is formed of about 75,000 hexagon-shaped lobules, each made from millions of liver cells.
All the blood in the body passes through these lobules every two minutes.
Unlike other organs such as the heart and lungs, the liver is the only one able to regenerate itself — even when up to 90 percent has been damaged.
Regular consumption of more than 30 units (15 pints of beers, five bottles of wine) a week risks chronic cirrhosis (damage) of the liver.
Carbon becomes incorporated into plants through photosynthesis, and then comes into humans when they eat greens.
There were massive — although not dangerous — amounts of carbon in the environment in the 1950s thanks to nuclear bombs being tested above ground, which was reflected in cells.
But after these were banned, the levels gradually began to fall.
It was this decline that the scientists used to estimate the age of cells.
The study found liver cells live for about a year on average, and never beyond three years.
But up to 20 percent — scientifically called diploid hepatocytes because they contain extra genes — had a lifespan of up to ten years.
These cells were more common in older patients, which the scientists said suggested they may have a role in ensuring the organ continues to replenish itself.
Dr Olaf Bergmann, the geneticist who led the study, said: ‘No matter if you are 20 or 84, your liver stays on average just under three years old.’
He added: ‘It is important to establish these characteristics of cell renewal in the adult liver, particularly to gain a better understanding of age-related diseases and liver cancer.’
Despite its ability to regenerate, there is mounting evidence that livers still age overtime due to mutations in cell genes.
This can lead to problems with normal cell function which triggers low-level inflammation in the organ, a risk factor for several diseases, reports a 2019 study in Computational and Structural Biotechnology.
The human body replaces about 330 billion cells every day — or one percent of the total, according to a 2016 study in PLOS Biology.
It also revealed that while some cells tend to only live a few days, others could last a lifetime.
The shortest lived cell is thought to be the sperm cell, which is stored for just three days on average before being replaced.