Researchers at Indiana University School of Medicine in the US found that the omega 3 fatty acids (DHA), the main ingredient of fish oil, significantly reduces the craving for alcohol.
The scientists, who made the discovery by chance while studying whether fish oil had any benefit for bipolar disorder, found that it "normalised" the behaviour of mice with the condition.
"They (the mice) are not depressed and when subjected to stress they do not become manic," lead author Dr Alexander Niculescu was quoted as saying by the Daily Mail.
However, an unexpected finding of the research was that the fatty acid also reduced the desire for alcohol, Dr Niculescu said.
He said: "These bipolar mice, like some bipolar patients, love alcohol. But the mice on DHA drank much less, it curtailed their alcohol abusive behaviour."
The researchers then gave DHA to alcohol-preferring rats and noted a similar effect.
"We believe a diet rich in omega 3 fatty acids may help the treatment and prevention of bipolar disorder, and may help with alcoholism as well," Dr Niculescu said.
There was now substantial evidence at the molecular level that omega-3 fatty acids worked on the brain in a similar way to psychiatric drugs, he said, adding that the next step would be clinical studies in humans.
The new study was published online in the journal Translational Psychiatry.