Prostate cancer is the second leading cause of cancer death for men in the United States. In fact, according to the American Cancer Society, 1 in 6 men will be diagnosed with prostate cancer at some point in their lifetime. Some studies suggest that omega-3 fatty acids may reduce the risk of certain cancers and have anti-inflammatory properties but the ACS reports that such studies are still inconclusive. But with so much talk about the Mediterranean diet and omega-3 fatty acids lowering the risk of heart disease, chances are that you or someone you know is probably consuming more fish oil supplements or eating more fatty fish like salmon, herring, or mackerel. Despite the health benefits of omega-3 fatty acids, a recent study found that fish oil may increase the risk of high-grade prostate cancer.
The latest study on the association between prostate cancer and omega-3 fatty acids, “Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial,” was published in the Journal of the National Cancer Institute, and was funded by National Cancer Institute and the National Center for Complementary and Alternative Medicine. The study analyzed levels of omega-3 fatty acids in the blood of 834 men who had been diagnosed with cancer, and 156 of them were diagnosed with high-grade cancer. (In the study, researchers defined omega-3 fatty acids as EPA, DPA and DHA.) They then compared the results with blood samples from 1,393 cancer-free men. Men with the highest level of omega-3 had a 43% increase in risk for prostate cancer and a 71% increased in risk for high-grade cancer (the most fatal) (Brasky, JNCI 2013).
It’s important to note that the study shows that there is an association between increased omega-3 fatty acid plasma levels and prostate cancer but does not demonstrate that the intake of omega-3 fatty acids causes prostate cancer. The study measured blood levels in the participants but did not include information on their eating habits. Thus, the effect between fatty acids from a fish source or supplements is not differentiated. As of now, the cause and effect relationship of the two is still unknown and much more research is needed. The study concludes that men with a history of prostate cancer should discuss with a health professional if fish oil supplements are safe for them. Since fish oil supplements are a concentrated form of omega-3 fatty acids, it can add up to a lot.
While the study sends a conflicting message to many who follow the Mediterranean diet or taking supplements, it’s simply important to remember that consuming any food in excess is not healthy. Men would benefit from consulting their doctor while continuing to read relevant research on this topic before taking fish oil supplements.
To learn more, check out the American Cancer Society for more information.