Connections Between Fish Oil and Prostate Cancer: Fact or Fiction?

Tanner,I have heard / read that omega 3 in excess can lead to prostate cancer. What is the story behind that?

Bryan D.

Thanks for the question and for following the blog, Bryan.  This is a question that has been a hot topic recently since the release of a study that showed a correlation between high blood levels of DHA (one of the omega 3 fats found in fish and omega 3 sups) and prostate cancer growth. I’m sure you aren’t he only one following the blog and my recommendations to take fish oil that has this concern.  I had the same concerns when I found out about the study connecting the two so I did some research of my own.

I am a huge proponent of fish oil supplementation so I needed to get all the facts.  When I took a deep dive into the study I found that the connections the researchers made was causal and very weak.  I also found a lot more research supporting the benefits of taking fish oil as a cancer fighter.  This should give you peace of mind and confidence to continue supplementing with fish oil.

What you need to know about the study

  1. The research indicated that people with the highest amount of omega-3 fatty acids in their blood had a 44%, 71%, and 43% greater risk of low-grade, high-grade and total prostate cancer, respectively.  The key thing you need to focus on here is that they the relationship was between omega-3 fatty acids in the blood and a higher risk of prostate cancer.  They have not found a cause for why the omega-3 blood levels were elevated.
  2. The researchers of the cancer study noted that very few of the subjects were actually supplementing with omega-3 fish oils so the findings don’t reflect the results of what happens when someone supplements with mega-doses of omega-3′s.
  3. The researchers were surprised because their findings were in contradiction to a stream of other studies that show DHA may have protective benefits to prostate cancer: study of 6000 swedish menstudy from New Zealand, and study tracking Japanese men.
  4. DHA levels in the blood don’t necessarily reflect DHA intake/supplementation.* This one is the big one and there is more research to support it. In this intervention study the low fat dieters showed a disproportionate boost in omega 3 blood levels despite the fact that they were given no special omega 3 boost. What the study actually concluded is that a low fat diet alters fatty acid patterns.
  5. Researchers are yet unable to identify why their subjects had such high omega-3 fatty acids in their blood.  Is it because their bodies aren’t able to use omega-3’s?  Does prostate cancer make us unable to utilize the omega-3’s we get from our diet the way diabetes render us unable to properly utilize insulin?

*This is similar to the way that cholesterol blood levels do not reflect dietary cholesterol.

At this point the research can’t provide any clear causal relationship between omega-3 intake/supplementation and prostate cancer.  In fact there is far more research showing the opposite causation.

All we can gather from the research study is that the men in the study who were more likely to have prostate cancer had higher levels of omega-3’s in their blood.  We have no idea why, what caused it, or what came first (cancer or high omega-3 levels).

What we do know for a fact is that omega-3 supplementation will improve your health, lengthen your life, protect you from cancer, and trigger your body to burn fat faster.  In my opinion those benefits far outweigh any perceived negatives.

For those of you in the market for quality fish oil at a good price I suggest SO3 Fish Oil by Stronger Faster Healthier (SFH).  It is what I use and sell in my gym.  In preparation for this article I reached out to SFH and they were nice enough to give me a 10% discount code offer to all of my readers that applies to their entire product line.  Type in the promo codeTMARTT before checkout to receive your discount.

This is a list of suggested reading for my male readers who are concerned about this topic:

Correlation vs. Causation by Precision Nutrition