#Prostate Cancer Risk and Omega 3 Oils: Really?

You have probably seen the headlines screaming recently about high levels of omega 3 oils causing a correspondingly high risk of prostate cancer. I was quite shocked since it seems to fly in the face of the thousands of studies showing omega 3 oil benefits. But, I don’t believe everything I see in the media by a long shot nowadays, so I wondered how robust the research was.

First, here is the researchers’ conclusion and you can read the full abstract here:

This study confirms previous reports of increased prostate cancer risk among men with high blood concentrations of LCω-3PUFA. The consistency of these findings suggests that these fatty acids are involved in prostate tumorigenesis. Recommendations to increase LCω-3PUFA intake should consider its potential risks.


What we have here does not actually show a causal effect at all. In short, high omega 3 levels were found in many men with prostate cancer. That doesn’t show at all a causal link and, in fact, also contradicts an earlier study done by the same researchers where they suggested the benefits outweighed any potential harm. In that one, they cautioned against making such causal associations and assumptions from vague links like this, but it seems they have forgotten their own advice here.

Who’s to say, for example, that men with prostate cancer don’t have some sort of mechanism going on where they naturally increase the omega 3 levels in the blood to help decrease inflammation? We know omega 3s are very anti-inflammatory. They could be helping and have nothing to do with the actual tumour causation at all.

From other stuff I have read, it seems that the researchers had no clue what diet the men were on or even if they were getting their omega 3 from actual fish or from supplements, let alone other dietary or lifestyle factors.

Of course, it all needs more looking at. Before I had a chance to look at in in more depth, my inbox was pinging with comments on the study and I am sure there will be more! Here are a couple for you..

Marilyn Glenville, a specialist in hormone disorders, makes some good points, I particularly like the one about lots of men with prostate cancer play tennis, therefore tennis causes cancer!:

This is not a randomised controlled trial but a trial comparing Omega 3 levels in men with prostate cancer with healthy men.   The men with prostate cancer had higher levels of Omega 3.  But you cannot extrapolate cause and effect from this finding.  It is like saying that if the majority of men with prostate cancer played tennis compared to healthy controls then tennis could trigger prostate cancer.

Also it is not clear whether the men who were already diagnosed with prostate cancer before they entered the study started taking Omega 3 supplements or eating more oily fish because of the previous research showing that Omega 3 could have a protective effect on prostate cancer.  In 2010, a large scale meta-analysis of 31 studies published in the American Journal of Clinical Nutrition found that there was a 63% decrease in the risk of death from prostate cancer with high fish consumption (Szymanski KM, Wheeler DC, Mucci LA: Fish consumption and prostate cancer risk: a review and meta-analysis. Am J Clin Nutr2010;92:1223-1233).

There is a wealth of evidence on the benefits of Omega 3 and one of the most staggering pieces of information came out in 2009 from the Harvard School of Public Health, where they stated that Omega 3 deficient diets cause up to 96,000 preventable deaths a year in the US (The Preventable Causes of Death in the United States: Comparative Risk Assessment of Dietary, Lifestyle, and Metabolic Risk Factors” stud, April 2009, PLoS Medicine).  The researchers estimated the number of deaths resulting from 12 preventable causes and Omega 3 deficiency ranked as the sixth highest killer of Americans.  A deficiency in these fats was classed as a bigger killer than high intake of trans fats.

Also there are many cultures such as the Japanese who eat high amounts of oily fish containing Omega 3 fatty acids and yet have one of the lowest prostate cancer death rates in the world.

Of course, the quality of Omega 3 fish oil supplements is important.  With fish oils, don’t just look at the amount of fish oil which might say 1,000mg.  The most important piece of information is the amount of EPA and DHA that the supplement contains which may be on the back of the label.

You are aiming for 770mg EPA and 510mg DHA per day.  The fish oil should be from natural deep sea fish, not farmed fish and each batch screened for contaminants e.g. Dioxins, PCBs and heavy metals like mercury and cadmium.

Also, Nutrigold were actually just doing a webinar on prostate health for us and so they have also produced a quite detailed response which you can read below. Obviously, part of what they are saying at the end is that the quality of the omega 3 you take is paramount (as did Marilyn above) and they point to their own Krill product, but actually I agree with them there and I do trust their products for safety and their research wholeheartedly.


Lastly, I had a quick peek on the largest natural medicine database there is at GreenMedInfo. Just go here and see the reams of studies on prostate cancer. On the first page there are two fish oil studies suggesting the exact opposite of this new one, for example!

Hope that helps give you some further info anyway. I’ll pass on anything else useful I find.

UPDATE: As predicted, my inbox has gone mad with comments on this as it seems so odd a finding! There are several I could share but actually the ANH has done a good report on it for us and I think that should answer most questions. Check it out (despite the rather punny title ;):

A tide of evidence washes away flawed fish oil prostate cancer study

Finally (promise), I always like to see what Dr Briffa has to say about these studies so here’s his post too for you:

My take on the fish oil and prostate cancer study

2 Replies to “#Prostate Cancer Risk and Omega 3 Oils: Really?”

    1. Ha, thanks Anthony, good to know I’m not the only cynic around! (And don’t worry about your links, if you paste them, they will generally go live automatically, ta).

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