Rancidity - the Link Between Fish, Fish Oil and Prostate Cancer?
By Bo Martinsen, MD and Anne-Marie Chalmers, MD
July 11th, 2013, national media reported that a study out of Ohio State University found that men consuming the most omega-3 (fish or fish oil) also had the highest risk of getting prostate cancer.
The study’s results and the news attention left a firestorm of worry about fish oil, and a lot of questions. How can omega-3 from fish and fish oil, which has been lauded in tens of thousands of research studies for its health benefits, promote cancer?
In the aftermath, the Ohio State University study received a torrent of criticism from the omega-3 research and academic community for its hastily drawn conclusions and poorly designed research protocol. (The study had, amongst other strange conclusions, also found that smokers had a lower risk of developing prostate cancer than non-smokers!).
In addition, the study’s conclusion contradicts the results of numerous other studies that reveal omega-3 helps reduce the risk of developing cancer. In fact, an Australian review on omega-3 and cancer published in January found that a daily dose of up to 3 grams of EPA/DHA per day had positive outcomes as an anti-cancer treatment, and worked as an effective adjunct treatment to chemotherapy.
So what exactly is going on, and why are studies finding such drastically different results? We believe part of the answer has to do with a little-discussed quality issue - namely rancidity.
When looking at omega-3 research to date, it is important to note that the quality of the oil used is rarely described - namely the rancidity or oxidation levels of the oil.
Oxidation levels in omega-3 oils can vary by 100 fold, and can be distinguished by taste and odor. Omega-3s with the lowest oxidation values have no smell or taste. On the other end of the spectrum, omega-3s with the highest oxidation values may smell or taste so bad that the manufacturer has to conceal the oil in gelatin capsules or add large amounts of flavoring.
While oxidation levels are almost never recorded by the researchers who use the oil in their studies, scientists are slowly starting to voice their concern over giving patients rancid oil on a daily basis.
While the long term effect of rancid fish oil has never been researched on humans, animal studies indicate that rancid fish oil may promote cancer and increase inflammation. So when a government study from Norway concluded two years ago that an overwhelming majority of fish oil capsules are rancid, the findings from Ohio State University should at least bring up the discussion of using oxidized omega-3.
For the consumer, the rancidity test is simple: Cut open the capsule. If the oil smells or taste fishy or makes you burp, it is likely rancid. Truly fresh fish oil has no taste or smell.
So does omega-3 really promote or prevent prostate cancer? With any study, we have to be wary before jumping to conclusions. We know that Japanese men, who consume vast amounts of omega-3 from fish and fish oil supplements, also have among the lowest prostate cancer rates in the world. Clearly the Ohio State University study has to be redesigned before they can explain their explain their results. A simple explanation for their findings may be that patients diagnosed with prostate cancer would likely start consuming more fish or omega-3 since it is reputed to be beneficial and healthy. An elevated blood sample reflecting diet from a single day does not mean that fish or fish oil caused the cancer.
Still, the study’s findings should serve as a wake-up call to all fish oil consumers: Rancid fish oil has no place in human nutrition.
On the other hand, removing pure, fresh fish and fish oil from the diet would be a health disaster. Omega Cure is the freshest fish oil in the world.
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