Much publicity has been given to an article published July 10, 2013 in the Journal of the National Cancer Institute, which indicated higher blood levels of omega-3 oils (fish oil) were associated with an increased risk for prostate cancer. One prior study in 2011 had a similar conclusion. This obviously raises concerns for those men who take fish oil.
At Cenegenics, we clearly advocate the use of fish oils for their benefit in cardiovascular disease, cognitive function, arthritis, among others. When evaluating such studies in relation to our recommendations regarding fish oil supplementation, we need to take various factors into consideration.
- Are the findings consistent with real world observations? Consider that:
- The rate of prostate cancer in the US is roughly 10 times higher than in Japan.
- Fish oil consumption in Japan is about 8 times higher than in the US.
- Are these results consistent with prior studies?
- The same team reported in 2011 that the use of fish oil supplements was not associated with any increased risk for prostate cancer.
- A 2010 meta-analysis of fish consumption and prostate cancer reported no overall relationship between prostate cancer and fish intake.
- 2 studies in 2001 and 2002 reported higher fish intake was associated with lower risk for prostate cancer incidence and death.
- A 2012 study revealed that a higher omega-3 fatty acid intake predicted better survival for men who already had prostate cancer.
- A study in JAMA in 2010 also found that a higher omega-3 fatty acid intake predicted better survival for men who already had prostate cancer.
- Is it clinically relevant?
- Statistics reveal a 7 fold higher risk of death for heart disease compared to prostate cancer in the general population.
- Let’s assume that higher fish oil intake reduces the risk for death from heart disease by 10% (a very conservative estimate), and increases the risk for death from prostate cancer by 50% (which it actually doesn’t do at all). Running the numbers would show that the risk of dying from heart disease would still be over 4 times higher than for prostate cancer.
- Were the higher blood levels due to fish oil supplementation?
- This study did not test the question of whether giving fish oil supplements (or eating more oily fish) increased prostate cancer risk. It looked only at blood levels of omega-3s. Levels are determined by intake, various dietary factors, metabolism and genetics.
- As mentioned above, the same team reported in 2011 that the use of fish oil supplements was not associated with any increased risk for prostate cancer.
- Does this study reveal an association, or a cause and effect? These are very different. An association does not necessarily imply causation.
- For example, it is possible that some component in whatever fish these particular subjects were consuming increased their risk. The blood levels might only be a marker of fish (i.e., carcinogen) intake.
- Does the study have any problems? Yes!
- The differences in fish oil levels between groups, although statistically significant, were very small, and essentially within normal variation. (3.62% in the control group, 3.67% in the low-grade cancer group, and 3.74% in the high-grade group).
In summary, this study adds little to our overall knowledge base, which taken as a whole, supports a neutral to beneficial effect of fish oil on prostate cancer. In addition, higher omega-3 levels are associated with lower rates of death from any cause. Higher levels are also associated with slower rates of cellular aging.
Bottom line – the risk/benefit analysis for fish oils remains very favorable.
Millions of people take fish oil. The distorted media attention, and erroneous interpretation that fish oil supplementation is bad, will likely cause large numbers of people to stop taking their fish oil. For many, this could lead to severe cardiovascular consequences, including death.
Despite all of the headlines, one thing is for sure. I will continue to take my fish oil!
References available upon request.