AsianScientist (Jul. 1, 2013) – Eating fish high in omega-3 fatty acids is associated with a 14 percent reduction in the risk of breast cancer later in life, finds a study published in the British Medical Journal.
Breast cancer is one of the most common cancers, accounting for 23 percent of total cancer cases and 14 percent of cancer deaths in 2008. Studies suggest that a healthy diet and lifestyle is crucial for the prevention of breast cancer, and dietary fat is one of the most intensively studied dietary factors closely related with risk.
The n-3 polyunsaturated fatty acids (n-3 PUFAs) – ALA, EPA, DPA and DHA – are involved in chemical messaging in the brain, and help to regulate blood vessel activity and areas of the immune system. The main dietary sources of EPA, DPA and DHA come from oily fish, while ALA is found mainly in nuts, seeds, and leafy green vegetables. Although n-3 PUFAs are the most promising types of fat to reduce cancer risk, results from human studies are inconsistent.
So a team of researchers from Zhejiang University in China set out to investigate the association between fish and n-3 PUFA intake and the risk of breast cancer. Levels were measured from both dietary sources and blood tests.
They reviewed and analyzed 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.
Marine n-3 PUFA was associated with a 14 percent reduction of breast cancer between the highest and lowest category of marine n-3 PUFA intake. The risk was lowest in Asian populations, probably because fish intake is much higher in Asia than in western countries, say the authors. However, no significant protective association was found for ALA – the plant based n-3 PUFA.
The results indicated that each 0.1 g per day or 0.1 percent energy per day increment of intake of n-3 PUFA derived from fish was associated with a five percent reduction in risk. To achieve this risk reduction, intake of oily fish such as salmon, tuna, or sardines should be 1-2 portions per person 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 authors write.
The article can be found at: Zheng J-S et al. (2013) Intake of fish and marine n-3 polyunsaturated fatty acids and risk of breast cancer: meta-analysis of data from 21 independent prospective cohort studies.
Source: BMJ; Photo: chloester/Flickr/CC.
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