Researchers have found that a high intake of omega-3 fatty acids, found in oily fish such as herring, salmon and mackerel, could reduce the risk of developing the disease by about 60 per cent, 'The Daily Telegraph' reported.

It also reversed the effect of an inherited gene known to increase the risk of prostate cancer, the study found.

According to the researchers, Omega-3 fatty acids may help to prevent prostate cancer by combating inflammation, an inappropriate immune system response, can be affected by diet, bacterial and viral infections, and genetic make-up.

They have based their findings on an analysis of diets of 466 men diagnosed with the disease and 478 healthy men.

Men who ate "dark" oily fish, rich in omega-3, one to three times per month had a 36 per cent lower risk of prostate cancer than those who never ate dark fish. And, eating oily fish more than once a week had even bigger protective effect, leading to a 57 per cent reduction in risk, the study found.

Omega-3 intake also had a major impact on the effect of hazardous variant of COX-2 gene which promotes inflammation known to be linked to prostate cancer. Men with the variant have an over five-fold increased risk of aggressive prostate cancer. But a high consumption of oily fish effectively wiped out this risk factor, according to the researchers.

Lead researcher John Witte of Californian University said: "The COX-2 increased risk of disease was essentially reversed by increasing omega-3 fatty acid intake by a half a gram per day.

"If you want to think of the overall inverse association in terms of fish, where omega-3 fatty acids are commonly derived, the strongest effect was seen from eating dark fish such as salmon one or more times per week."

The findings are published in the 'Cancer Research'