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Natural Awakenings Sarasota / Manatee / Charlotte

Possible Rancidity Link Between Fish Oil and Prostate Cancer

Jun 01, 2014 03:05AM ● By Bo Martinsen

by Bo Martinsen
Last year, a study from Ohio State University (OSU) determined that men consuming the most omega-3 fatty acids from fish or fish oil also had the highest risk of getting prostate cancer, a simple correlation that did not indication causation. But doubt was raised that omega-3 from fish and fish oil, which has been lauded in thousands of research studies for its health benefits, could promote cancer.
The OSU study received a torrent of criticism from omega-3 proponents and the academic community for its hastily drawn conclusions and poorly designed research protocol. In addition, the study’s conclusion contradicts the results of numerous other studies. A 2013 Australian research review in the British Journal of Medicine concludes that a daily dose of up to three grams of docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA) per day may have potential as an effective adjuvant to chemotherapy treatment and help ameliorate some of the secondary complications associated with cancer.
When looking at omega-3 research to date, it is important to note that the quality of the oil used is rarely described. The drastically different results of scientific studies may be due to a little-discussed quality issue: the rancidity, or oxidation levels, of the oil. Oxidation levels in omega-3 oils can vary tremendously, 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 the researchers studying fish oil rarely mention oxidation levels, scientists are starting to voice their concern over giving patients rancid oil on a daily basis. As researchers from University of Auckland, in New Zealand, point out in a review published in BioMed Research International, animal studies indicate that rancid fish oil may promote cancer and increase inflammation. A government study from Norway two years ago concluded that an overwhelming majority of fish oil capsules are rancid. In light of this information, the OSU findings should at least trigger consideration of oxidation and rancidity as an issue in the conflicting results about omega-3 fatty acids.
We must be wary before jumping to conclusions that omega-3 really promotes or prevents prostate cancer. The OSU study needs to be redesigned to verify its results. An elevated blood sample reflecting diet from a single day does not mean that fish or fish oil caused the cancer, but 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.
For the consumer, the rancidity test is simple. Cut open the capsule. If the oil smells or taste fishy or causes burping upon consumption, it is likely rancid. Truly fresh fish oil has no taste or smell.
Bo Martinsen, M.D., is the co-founder and CEO of Omega3 Innovations, makers of Omega Cure. He is certified by the Educational Commission for Foreign Medical Graduates. For more information, call 866-414-0188 or visit
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