About 70 per cent of more than 600 people surveyed by Hepatitis Australia thought liver cleansing diets or detox products, such as those available from pharmacies, were beneficial.
But liver-cleansing products have no proven medical benefits and can even be harmful, said Associate Professor Simone Strasser of the Gastroenterological Society of Australia, The Australian reported.
"Just doing a one-off detox, which people like to do around New Year particularly because of all the excesses of the Christmas period, has absolutely no value for the liver at all," she said.
"Fat builds up in the liver cells but these diets don't do anything for that. They are called detox diets, but there are no toxins that actually build up in the liver," she told the AAP news agency.
Instead, people should use this time of year to look at their overall lifestyle habits, the Sydney specialist said.
Eating a balanced diet, maintaining a healthy weight and limiting alcohol consumption all year round was the key to a healthy liver.
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Detox diets could even be harmful, especially for people with established liver disease, Strasser said.
Sudden and rapid weight loss could lead to an increase in the accumulation of fat in the liver, worsening fatty liver disease, she said.
About a quarter of all Australians have fatty liver disease, but obese people have an 80 per cent chance of the condition.
The disease causes inflammation and scar tissue and can lead to cirrhosis and liver cancer, the same conditions caused by excessive alcohol consumption.
"People often believe the hype about rejuvenating their liver by detoxing in January however a quick fix is not the way to approach liver health," said Hepatitis Australia chief executive Helen Tyrrell.