Obviously, the big news of this past week in the world of omega-3s is a study published claiming that “omega-3s cause prostate cancer.” I have had friends and family call, text, stop me in person, and email their concerns about what is clearly a headline grabbing ploy by the press to make a huge deal out of poorly designed manuscript masquerading as a scientific publication.
First of all, the study did not look at omega-3 supplementation, but was a look at if there is an association between Vitamin E and selenium and cancers (including lung, colorectal, and prostate). The manuscript was done looking retrospectively at people with prostate cancer and what their omega-3 levels were at a single point in time. When I did a study looking at omega-3 levels and documented suicide, I was very careful not to conclude that low omega-3 levels CAUSE suicide because that would not be a true statement. Low omega-3 levels measured were ASSOCIATED with a 62% increase risk they came from a suicide, but there is absolutely NO WAY POSSIBLE to conclude a causal relationship. These researchers and the press that followed obviously did not feel the need to adhere to such ethical parsing of words in order to grab headlines. Come on, the study showed a possible increase of prostate cancer had a confidence interval of 0-192%!!!!
I am always amazed, though I’m not sure why, when the press blow things out of proportion about a study demonstrating their complete lack of understanding of scientific studies. I could go into details for a long time, but let me just say clearly that this case-control study was not designed to look at the question in which the researchers draw their incorrect conclusions. In the worst case, there may be an association between higher omega-3 levels and prostate cancer, but to conclude that omega-3s cause prostate cancer? Really??? Given that the study was a single snapshot looking at if someone has prostate cancer and what their omega-3 blood level was at that moment, it is completely reasonable to state that prostate cancer causes higher omega-3s in the blood. Or that people with prostate cancer increased their fish or supplement intake because it is fairly well known that omega-3s may be helpful in cancer due to their anti-inflammatory properties. But that is not what catches headlines.
Not sure which argument you might want to use, but the biggest one is that it was a study not designed to look at this question and the investigators completely drew conclusions from data that don’t support their conclusions. So which argument do you want? You mean besides that it is a poorly designed evaluation of data from a totally different study never designed to look at prostate cancer and omega-3s and should have never been published? Or the part where countries and societies that have the most fish intake actually have the lowest rates of all cancers including prostate? Or that there is specific research designed to actually look at that question and everyone of those studies shows decreased rates of cancer? Or that this same study also showed that there are higher rates of prostate cancer in nonsmokers and nondrinkers (so should we recommend everyone drink, smoke, and stay away from fish?)?
One rebuttal can be found at: http://www.nutraingredients-usa.com/Research/Experts-slam-omega-3-link-to-prostate-cancer-as-overblown-scaremongering. A more scientific-oriented review can be found at http://examine.com/blog/fish-oil-and-your-prostate .
What we do know is that omega-3s are anti-inflammatory and well known and documented to decrease overall and cardiovascular mortality, the incidence of cancer, heart disease, and have a positive benefit on brain health especially in the absence of brain health. What is really sad is how many people will decrease their intake of fish or stop their supplementation because of ridiculous studies/reporting like this. How much additional suffering will occur because of it?