NLM Director’s Comments Transcript
Fish Oil Linked to Prostate Cancer Risk: 09/03/2013

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Greetings from the National Library of Medicine and MedlinePlus.gov
Regards to all our listeners!
I'm Rob Logan, Ph.D. senior staff National Library of Medicine for Donald Lindberg, M.D, the Director of the U.S. National Library of Medicine.
Here is what's new this week in MedlinePlus.

Men with comparatively higher levels of fish oil (or omega-3 fatty acids) in their blood have a 44 percent overall higher risk to develop prostate cancer, finds a study recently published in the Journal of the National Cancer Institute.
The findings (derived from a large randomized controlled trial called SELECT that assesses the impact of several supplements and vitamins on prostate cancer risk) found men with high levels of fish oil in their blood comparatively have a 71 percent increased risk to develop a more aggressive form of prostate cancer — and a 43 percent higher comparative risk to develop slow growing prostate cancer.
The study’s research team (from the Fred Hutchinson Cancer Center in Seattle) previously demonstrated an association between prostate cancer and high blood levels of DHA, which is one of three omega-3 fatty acids derived from oily fish and fish oil supplements. The current study is one of the first assessments of the impact of all three fatty acids on prostate cancer.
The current study compared blood levels of omega-3 fatty acids in 834 men diagnosed with prostate cancer with blood samples from a random sample of 1,400 men who did not develop the disease. About 35,500 persons participated in the broader SELECT trial, which is partially funded by the National Cancer Institute and the National Center for Complementary and Alternative Medicine.
The study’s 12 authors explain they could not discern if the risk of prostate cancer was derived from eating fish rich in omega-3 fatty acids (such as salmon or herring), or from fish oil supplements.
Either way, the authors note the study suggests higher overall fish oil levels may pose a more significant prostate cancer risk than many persons realize.
In an interview after the release of the study’s findings, the study’s lead author told HealthDay (and we quote): ‘fatty acids have been promoted as a blanket anti-chronic disease... ‘but nutrition is more nuanced, as is disease occurrence’ (end of quote)
While the study’s methods suggest there is a statistical association between an increased risk of developing prostate cancer and fish oil consumption, the authors note these findings do not demonstrate fish oil consumption causes prostate cancer. The authors explain the latter needs to be assessed in future studies.
However, the study’s lead author, Howard Brasky Ph.D., told Time the results suggest men with a family history of prostate cancer should discuss whether it is safe for them to take fish oil supplements or regularly eat salmon, herring and other oily fish.
Meanwhile, MedlinePlus.gov’s fish oil page provides comprehensive information about the widely available, over-the-counter food supplement. The page explains there is evidence fish oil supplements may be effective to counter high triglycerides, which are associated with heart disease. The page also lists an array of diseases and conditions where fish oil supplements are: likely to be effective, are possibly effective, possibly ineffective, likely ineffective, and where insufficient evidence exists to suggest effectiveness.
MedlinePlus.gov’s fish oil page additionally provides information about recommended doses of fish oil supplements and details its interactions with prescription medications as well as other herbs and food supplements.
MedlinePlus.gov’s fish oil page is found within the drugs and supplements section accessible near the top center of MedlinePlus.gov’s home page.
A downloadable guide (from the Prostate Cancer Foundation) that provides nutrition information can be found in the ‘nutrition’ section of MedlinePlus.gov’s prostate cancer health topic page. A guide to prostate cancer prevention (provided by the National Cancer Institute) can be found in the ‘prevention’ section of MedlinePlus.gov’s prostate cancer health topic page.
To find MedlinePlus.gov’s prostate cancer health topic page, type ‘prostate cancer’ in the search box on MedlinePlus.gov’s home page. Then, click on ‘prostate cancer (National Library of Medicine).’ MedlinePlus.gov also has a health topic page devoted to dietary fats.
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