Eating oily fish on a regular basis could reduce a woman's risk of developing breast cancer by up to 14%, a new study indicates.

Over 2,500 women are newly diagnosed with breast cancer in Ireland every year. Research indicates that a healthy diet and lifestyle can play a crucial role in lowering the risk of the disease.

Scientists in China decided to focus on intake of n-3 polyunsaturated fatty acids (n-3 PUFAs), some of which are found in oily fish, such as salmon and sardines. These fatty acids have a role in how the brain sends chemical messages. They also help to regulate parts of the immune system and blood vessel activity.

Until now, studies on the role of n-3 PUFAs in reducing the risk of breast cancer have been inconsistent.

The scientists analysed the results of 26 studies from Europe, Asia and the US, involving more than 800,000 women and 20,000 cases of breast cancer.

They found that women who consumed the highest amounts of marine n-3 PUFAs - those found in oily fish - had a 14% reduced risk of developing breast cancer compared to women who consumed the lowest amounts.

The study found that overall, each 0.1g of oily fish-related n-3 PUFA that was consumed each day was associated with a 5% reduction in risk. To achieve this risk reduction, they said, people should aim to eat one to two portions of oily fish per week.

"Our present study provides solid and robust evidence that marine n-3 PUFA are inversely associated with risk of breast cancer. The protective effect of fish or individual n-3 PUFA warrants further investigation of prospective studies," the team from Zhejiang University concluded.

Details of these findings are published in the British Medical Journal.