Women eating two helpings a week of oily fish such as salmon may gain protection against breast cancer, claim researchers.
A major review of studies found adding this amount of fish to the diet cuts the breast cancer risk by up to 14 per cent.
Fish supplies omega-3 fatty acids which are essential for brain development and also thought to reduce inflammation of the brain, cardiovascular system and other cells.
The best dietary source of omega-3 fatty acids is oily fish because the human body cannot produce them.
Around 2800 New Zealand women and 20 men are diagnosed every year, according to the NZ Breast Cancer Foundation.
Previous research has suggested that omega-3 is the most promising type of fat to cut cancer risk, but results have been inconsistent.
A team of researchers based in China set out to investigate the link between fish and omega-3 intake and the risk of breast cancer.
They measured intake from both dietary sources and blood tests, according to a report in the British Medical Journal.
They reviewed and analysed the results of 26 studies from the United States, Europe and Asia involving over 800,000 participants and over 20,000 cases of breast cancer.
The latest study found an extra 0.1 g or 0.1 per cent of energy per day derived from omega-3 fatty acids in fish was linked with a five per cent reduction in risk.
Overall, omega-3 fatty acids from fish sources was linked with a 14 per cent cut in breast cancer between the highest and lowest levels of intake.
The risk was lowest in Asian populations, probably because fish intake is much higher in Asia than in western countries, say the authors.
To achieve this level of risk reduction, women should eat one to two portions a week of oily fish such as salmon, tuna or sardines.
The authors say their analysis, together with previous publications, supports a "protective role" of omega-3 fatty acids from fish on the incidence of breast cancer.
They say the study provides "solid and robust evidence" which could be enhanced by additional research comparing women's omega-3 dietary intake and breast cancer incidence, it says.
Katherine Woods, Research Information Manager at Breast Cancer Campaign said the research may have failed to account for women with healthier diets being leaner.
"While this research reported a reduction in breast cancer risk of 14 per cent for women consuming the highest levels of a particular type of fatty acid, it is important to note that body mass index (BMI) was not factored into the findings which could go some way to explaining this link," she said.
"Further research is needed in order to understand any links between BMI, fatty acids found in fish and breast cancer risk.
"Maintaining a healthy weight, exercise and reducing alcohol intake can help reduce the risk of breast cancer and other diseases."
- DAILY MAIL