Consuming fish oils can significantly lower a person's risk of developing breast cancer, according to a new study published in the BMJ.

The researchers reviewed 21 different independent prospective cohort studies, they found that a high intake of fish and marine n-3 polyunsaturated fatty acids was associated with a 14 percent reduced risk of breast cancer.

Breast cancer is a form of cancer that develops from breast cells. It is one of the most common cancers, responsible for nearly a quarter of all cancer cases and 14% of cancer deaths in 2008. More than 200,000 women are diagnosed with the disease each year.

Lifestyle and diet play a very important role in preventing the cancer from developing.

For people to actually reduce their risk they should consume at least 1-2 portions of oily fish per week - such as sardines, salmon, tuna.

n-3 PUFAs are all omega 3 essential fatty acids that have to be acquired through diet - as they cannot be produced in the body. n-3 PUFAs include: α-Linolenic acid (ALA), Eicosapentaenoic acid (EPA), Docosapentaenoic acid (DPA), and Docosahexaenoic acid (DHA).

These acids play a vital role in the brain's chemical messaging and regulation of blood.

Oily fish provide EPA, DPA and DHA, and nuts and leafy green vegetables provide ALA.

Even though n-3 PUFAs were previously found to have positive effects on cancer risk, results from previous human studies have varied significantly.

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In order to find out whether n-3 PUFAs have anti-cancer properties, a team of Chinese researchers set out to assess the link between fish and n-3 PUFA intake and the risk of breast cancer, by reviewing and analyzing the results of 26 different international studies.

The team analyzed data on approximately 800,000 participants and more than 20,000 cases of breast cancer.

Comparing the lowest and highest category of marine n-3 PUFA intake, the investigators identified that high Marine n-3 PUFA intake was associated with a 14 percent reduced risk of breast cancer.

In addition, for every 0.1 g per day increase in the consumption of n-3 polyunsaturated fatty acid (n-3 PUFA) from fish, the risk of breast cancer decreased by 5 percent.

However, the plant based n-3 PUFA "ALA" seemed to have no anti-cancer properties.

The authors said that their finding "supports a protective role of marine n-3 PUFA on the incidence of breast cancer."

They concluded:

"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."

A report in Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, similarly found that fish oil supplements may play a role in preventing breast cancer.

Omega-3 fatty acids, as well as their metabolite products have also been shown to slow the growth of triple-negative breast cancer cells better than cells from luminal types of cancer, according to research presented at the AACR Annual Meeting 2013.

Researchers at Fox Chase Cancer Center have found that omega-3 fatty acids could be a safe and beneficial booster for tamoxifen therapy.

Written by Joseph Nordqvist