|Oily fish are rich in polyunsaturated fatty acids|
"Eating two portions of oily fish [a week] could protect women against breast cancer," reports the Mail Online website. The story comes from an analysis of the best available evidence on the link between oily fish and breast cancer risk.
Researchers were particularly interested in assessing the effects of a type of fatty acid called omega-3 polyunsaturated fatty acid (n-3 PUFAs). These fatty acids are found in oily fish such as salmon and tuna, and some plant sources.
The analysis included more than 800,000 women. Just over 20,000 of these women developed breast cancer during follow-up. Women with the highest intake of n-3 PUFAs from fish (marine) sources were found to have a 14% reduction in risk of breast cancer compared with women with the lowest intake.
However, as with all observational studies and reviews, the pooled results may be affected by factors (confounders) other than marine n-3 PUFA intake. For example, women who eat a lot of fish may be more likely to lead healthier lifestyles, such as not smoking.
But a link between n-3 PUFAs and a reduced cancer risk is plausible – n-3 PUFAs are known to reduce the production of the hormone oestrogen, which can stimulate abnormal cell growth.
Overall, this review is a good summary of the current state of knowledge about the link between n-3 PUFA intake and risk of breast cancer.