Like a generator kicking in when the power fails, an antioxidant system acts as a back up to help sustain the liver when other systems are missing or compromised, researchers have discovered.
The newly found system, reported in the journal Nature Communications, is fuelled by methionine, an amino acid that cannot be manufactured in the body and does not come from herbal teas or supplements,
People get it only by eating protein. Methionine is found in high levels in eggs, meat, fish, Brazil nuts, sesame seeds and cereal grains.
"This is an important finding," said Ed Schmidt, professor at the Montana State University.
"It tells us about humans and all living things. It is an alternative way to maintain the balance you need in your cells to be alive," Schmidt added.
Some vitamins and supplements act as antioxidants, Schmidt said. They help protect cells from the damage that can lead to ageing, cancers and inflammatory diseases.
To investigate further, Schmidt’s lab generated mice whose livers lacked key components of two known natural systems in liver cells: the thioredoxin and glutathione systems.
The mice were not robust. They were on the brink of failure, Schmidt said. And yet they survived.
Pursuing the mystery, the researchers found the third antioxidant system and said it has broad implications for health issues in humans.
"Methionine, a sulphur-containing amino acid that is required in our diet so our cells can make proteins, is also a potent, but previously unrecognised antioxidant that, unlike any other antioxidant tested to date, can sustain the liver when the two other systems are absent or compromised," Schmidt added.