Does fish oil cause prostate cancer?

News of a newly-published study titled “Plasma Phospholipid Fatty Acids and Prostate Cancer Risk in the SELECT Trial” has been covered in the mainstream media over the last several days, leading to quite a bit of confusion. Because of this study, many now believe that taking fish oil will increase the risk of prostate cancer. Here are the facts:

• The study of 834 men with prostate cancer showed that men with the highest levels of EPA/DHA in their blood were about 1.5 times more likely to have prostate cancer.
• The study did not analyze the use of fish oil supplements associated with prostate cancer risk. Most of the men in the study were not taking fish oil supplements.
• This is an observational study looking for associations between 2 factors and does not tell us anything about cause/effect.
• Men living in Japan, where the intake Omega-3 fats is highest in the world, have the lowest incidence of prostate cancer. This contradicts the conclusion that the high Omega-3 is the reason for the increased risk.
• Prostate cancer is highest in men who eat the Standard American Diet (S.A.D.). When Japanese men move to the U.S., their risk of prostate cancer increases to that of American men. That indicates that there is something about the American diet that promotes cancer. The S.A.D. is high in processed foods which is lacking in nutrients and antioxidants and is high in sugar, trans-fats, pesticides, and preservatives.
• There may be many other factors at play in this association. Most fish in the U.S. is farm-raised and full of toxins from contaminated water and that could be a reason that American men with high blood levels of Omega-3 have increased risk of prostate cancer.
• We will not have the answer to the question about fish oil supplements and prostate cancer until a double-blind, placebo-controlled, long-term study is done.
• My advice would be to be cautious about the use of high dose fish oil in men at high-risk of or already diagnosed with prostate cancer and take into consideration other conditions which may benefit from fish oil. I would also advise taking high quality, pharmaceutical grade fish or krill oil and combine with Omega-3’s (ALA) from flax and other seeds.