Fish Oil Causes Prostate Cancer?

I’m sitting in my hotel yesterday morning enjoying a cup of coffee.

As I’m paging through the USA Today (guilty pleasure #1 when traveling) and listening to a morning TV show (guilty pleasure #2 when traveling) I heard the news anchor say something that almost made me spew my coffee.

“If you’re chewing your fish oil right now, immediately spit it out.  A new study just released found fish oil increases the risk of prostate cancer by 71%.”

As someone who takes fish oil daily, is an educator for a fish oil company, and when asked what supplements you should take, respond with “fish oil and vitamin D” I needed to hear more.
Because I work with a lot of media, I also had a hunch that there was more to tell than just what the TV anchor was reporting.

The devil is in the details.

The little blurb I heard also conflicted with a large meta analysis (review of many studies) published in 2010 that showed fish consumption was protective against prostate cancer mortality.

Back to the study at hand, which I’ve now had the chance to read in its entirety and got to talk with a handful of colleagues about.  The authors in this particular study said their results agreed with two other studies that had similar findings.  However they left out the many other studies that didn’t have similar findings, including the large review study published just a few years ago.

Let’s pick through this a bit to hopefully help calm your nerves.

Translating research into results.

This was a large study – what’s called an epidemiological study, where researchers pick an outcome (in this case, prostate cancer) and then try to determine what may have led to that outcome (in this case, omega-3 levels of patients who had what’s called high grade prostate cancer).

These types of studies are OK, but certainly can not determine cause and effect.  I had a long conversation with my friend, nutrition expert and physician, Dr. Hector Lopez, who summed it up well “this type of study and data limit the strength of the findings – these are not cause and effect studies.”

In other words, from the findings of this study, it is 100% impossible and irresponsible to conclude that fish or fish oil cause an increase in risk for prostate cancer, though this was seen all over the media today.  And, interestingly, even the authors of this current study admit they don’t know why omega-3s – which normally display anti-cancer effects across the board – would promote prostate tumors.  Even stranger since, in the authors words, the men in the study had  “very low concentrations of omega-3's."  We'll talk more about their concentrations in a minute.

Let’s look a bit more in depth at the study itself. 

The method used for analysis of omega-3 levels was a single blood test, which was done when these subjects entered the long term study.

But there’s a major flaw in that type of analysis.  Single blood tests are not an accurate way of measuring omega-3 levels. This is simply an acute measure of omega-3 intake; something that could be affected by eating a single fish meal or taking a single dose of fish oil, but are not an accurate assessment of long term intake (the most important measurement).

In fact, a recent research study by well known omega-3 expert, Dr. Bill Harris, confirmed that very point – single blood tests, like those used in this particular study, are not an accurate assessment of true, long term intake.  I also had a lengthy conversation with omega-3 researcher and expert Dr. Doug Bibus today who actually does blood serum tests to truly measure the level of omega-3 in your blood tissue and he confirmed my thoughts. If you do in fact want to get your blood tissue measured, go to http://www.Omega3Test.com and you can have it done.

Speaking of the analysis, when you look closely at the actual blood values — again, not a truly accurate tool to measure blood tissue levels of omega-3 fats, but still what was used in this study — the difference between the combined cancer group and control group was just 0.2%.  The blood level was 4.66% in the combined cancer group vs. 4.48% in the control (no cancer).  

What about countries with high seafood intakes who naturally have higher omega-3 intakes because of their diet?  We don’t see levels of prostate cancer among men skyrocketing in Japan, Iceland, etc.  So that conclusion isn’t valid in our opinion.

Research is like a woman’s bikini.  It can hide or reveal as much as you want.

So, all that being said, it’s important to take all studies with a grain of salt and keep your eye on the big picture.  Again, research can hide or reveal whatever you want.  I’m not saying these researchers or others are deceitful; there are just different statistical analyses, ways to look at data, etc that may not be appropriate in different situations.  That’s why it’s important to look at multiple studies (or keep reading this blog so we can do that for you).

Alright, so where do we go from here?

3 Take Home Points:

1. Hopefully you’re eating fish regularly — wild salmon, sardines, anchovies, tuna, etc — 2-3 times per week.  That’s first and foremost.  Food first as fish offers a whole slew of other great nutrients, above and beyond just omega-3’s.
2. The abundance of well controlled research, most governing bodies, well informed researchers and experts who study and talk about this regularly … agree that supplementing with a high quality fish oil is safe, healthy and smart.  We use, like and trust Nordic Naturals – take it ourselves and give it to our two girls.
3. While we believe fish oil is a great piece to the dietary puzzle, it is not a magic bullet.  It is also important to decrease less healthy fats (processed saturated fats, trans fats), soybean oil, corn oil, fried foods, etc. in the diet.

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