Dr Gigi Chow

Posts Tagged ‘prostate cancer’

The Omega-3 Rebuttal: Fish Oils Linked to Prostate Cancer…Are You Serious??

In Diet, Natural Cancer Prevention, Stay Healthy on August 7, 2013 at 2:12 pm

Here is another one-liner attack on nutritional supplements that is spreading like wildfire across the internet: “Omega 3 Supplements linked to Prostate Cancer”  This involves a recent study conducted at the Fred Hutchinson Cancer Research Center in Seattle which has supposedly found a link between high concentrations of omega-3 fatty acids from fatty fish and fish-oil supplements and an increased risk of prostate cancer. According to the report, omega-3 fatty acids are linked to “a 44% increased risk of ‘low-grade’ prostate cancer, and a 71% increased risk of “high grade” (i.e. aggressive) cancer.

This study’s conclusions are contrary to numerous studies on the subject showing the benefits of omega-3 fatty acids in relation to prostate cancer. A Harvard study examined the link between dietary fish consumption and the risk of metastatic prostate cancer. The study involved 47,882 men over twelve years, and found that eating fish more than three times a week reduced the risk of prostate cancer but had an even greater impact on the risk of metastatic prostate cancer. For each additional 500 mg of marine fat consumed, the risk of metastatic disease decreased by 24%!

Another study found that fish intake may improve prostate cancer survival: 20,167 cancer-free men were followed for 22 years. While this study did not find that increased fish consumption reduced prostate cancer, it found that among the men diagnosed with prostate cancer, those consuming fish  more than 5 times/week had a 48% lower risk of prostate cancer death than men consuming fish less than once weekly.

What many readers don’t realize when they read the one-liner story about the Fred Hutchinson Research study is that the study is flawed in so many ways, below are just a few of them:

1) The data of this study came from a previous study that DID NOT evaluate omega-3 intake and prostate cancer risk, but from a study the effect of selenium and vitamin E on prostate cancer. Using data from an unrelated study (vitamin E and selenium) to draw conclusions about dietary intake of omega-3 oils and prostate cancer is purely nonsensical!

2) It is also hugely important to realize that the authors of this study did not assess any of the participants’ dietary intake of fatty fish or omega-3 nutritional supplements. There is no documentation of fish oil or dietary fish intake in the study group. Also, researchers did not discuss diet or supplementation at the beginning, during, or end of the study. The study’s conclusions are based wholly on the results of a single blood test.

3) Identifying one particular physiologic marker in a group of individuals with a given condition – in this case, an elevated omega-3 level in men with prostate cancer – does not prove causation, especially when that marker can be influenced by diet or behavior and is only measured at a single point in time.

4) A number of confounding risk factors might have influenced the purported outcomes in the study, despite attempts by the investigators to account for them:

–53 percent of the subjects with prostate cancer were smokers.

–64 percent of the cancer subjects regularly consumed alcohol.

–30 percent of the cancer subjects had at least one first-degree relative with prostate cancer.

–80 percent of the cancer subjects were overweight or obese.

Despite the fact that the study showed no causal link between prostate cancer and fish oil supplementation or the presence of omega-3s in blood, the paper’s senior author made the following blanketed statement in a press release : “We’ve shown once again that use of nutritional supplements may be harmful.” Have you ever heard such an absurd conclusion? It’s one thing if this study is founded on sound science and research methods, but it is not.  The logic of its ridiculous conclusion and its subsequent application to the entire field of nutritional supplements is beyond…what’s the word…unscientific.

Don’t believe the hype.

Other references: