Higher marine omega-3 fatty acid intake linked with lower breast cancer risk in postmenopausal women
Tuesday, July 2, 2013. The results of a meta-analysis published on July 27, 2013 in the British Medical Journal add evidence to a protective effect for marine omega-3 polyunsaturated fatty acids against the risk of breast cancer.
Omega-3 fatty acids, which include eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA) and docosapentaenoic acid (DPA) found in marine oils, and alpha-linolenic acid (ALA) which occurs in plants, are polyunsaturated fats that have been associated with a lower risk of cancer and cardiovascular events, however, their presence is often less than optimal in the standard Western diet.
For their analysis, researchers from Hangzhou, China selected 26 articles that included a total of 883,585 women from the U.S., Europe and Asia, among whom there were 20,905 cases of breast cancer.
Eleven studies examined the association between fish intake and breast cancer risk, 17 examined the association between marine omega-3 fatty acids and risk, 12 evaluated ALA's association, and 10 analyzed the association between total omega-3 fatty acid intake and risk of the disease.
For women whose intake of marine omega-3 fatty acids was among the highest there was a 14% reduction in the risk of breast cancer in comparison with those whose intake was lowest. The risk was similar for marine omega-3 fatty acids measured as dietary intake and for tissue biomarkers.
The researchers determined that for each 100 milligram increase of marine omega-3 fatty acid intake, the risk of breast cancer was lowered by 5%. No significant associations were found for fish or ALA.
Further analysis of the data indicated that the protective effect was significant for postmenopausal, but not premenopausal women, which could mean that long term exposure is necessary to derive a benefit.
Possible anticancer mechanisms for marine omega-3 fatty acids include regulation of factors involved in the signal transduction of cell growth, or involvement in programmed cell death.
There is also evidence that the fatty acids could reduce the production of estrogen, which stimulates the growth of estrogen receptor-positive malignancies.
"Our present study provides solid and robust evidence that marine omega-3 PUFA are inversely associated with risk of breast cancer," Duo Li and colleagues conclude. "The protective effect of fish or individual n-3 PUFA warrants further investigation of prospective studies."
