Fatty Fish and Fish Oils are a Safe Supply of Omega-3s
A new study suggests that raised levels of a particular fatty acid in the blood may be detrimental to patients undergoing cancer therapy. The Daily Mail suggests cancer patients should be concerned about eating herring, mackerel and omega-3 supplements when undergoing chemotherapy.
First, the recommendation is based on data obtained in mice (Roodhart et al, 2011; Daenen et al, 2015) implanted with cancer cells, orally gavaged (force-fed) with fish oils, and treated with chemotherapeutic agents. While scientifically interesting, these results are not applicable to humans. The volumes used in the mice studies are not consistent with human intake.
Second, the nutritional relevance of 16:4(n-3) [hexadecatetraenoic acid] is disputable. While platinum-induced fatty acids (PIFA) can be detected in seafood sources and post-ingestion in blood, the amount of hexadecatetraenoic acid in the blood is minute relative to the absorption of other dietary fatty acids. The quantities are so trivial that 16:4(n-3) concentrations are not reported when measuring fish intake and red blood cell fatty acid composition in Danish adolescents or Mozambique girls.
Third, in 2011 similar claims from these researchers with respect to the avoidance of fatty fish or fish oil supplements during chemotherapy treatment were disputed. Again, the experimental evidence in mice undergoing chemotherapy does not justify the media interpretation.
Fourth, there is evidence that EPA and DHA may be an effective adjuvant during chemotherapy treatment. The American Institute for Cancer Research recognizes that eating fish may protect against cancer.
Fifth, omega-3 intakes, especially in the US, are low. Globally, many people have an omega-3 index below the recommended 8%. After an extensive review of the scientific literature, the 2015 Dietary Guidelines Advisory Committee (DGAC) acknowledged that neither mercury or organic pollutants outweighed the benefits of increasing omega-3 intake.
The 2015 DGAC encourages consumption of seafood, wild caught or farmed, because of their omega-3 fatty acids eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). The consumption of fatty fish and fish oil supplements is safe.
Don’t let controversial headlines and fearmongering affect healthy behaviors. Fish oil supplements are a safe source of omega-3s.
Daenen LGM, Cirkel GA, Houthuijzen JM, Gerrits J, Oosterom I, Roodhart JML, van Tinteren H, Ishihara K, Huitema ADR, Verhoeven-Duif NM, Voest EE. Increased plasma levels of chemoresistance-inducing fatty acid 16:4(n-3) after consumption of fish and fish oil. 2015 JAMA Oncol doi: 10.1001/jamaoncol.2015.0388
Roodhart JM, Daenen LG, Stigter EC, Prins J-J, Gerrits J, Houthuijzen JM, Gerritsen MG, Schipper HS, Backer MJG, van Amersfoort M, Vermaat JSP, Moerer P, Ishihara J, Kalkhoven E, Beijnen JH, Derksen PWB, Medema RH, Martens AC, Brenkman AB. Voest EE. Mesenchymal stem cells induce resistance to chemotherapy through the release of platinum-induced fatty acids. 2011 Cancer Cell doi: 10.1016/j.ccr.2011.08.010
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Murphy RA, Clandinin MT, Chu QS, Arends J, Mazurak VC. A fishy conclusion regarding n-3 fatty acid supplementation in cancer patients. 2012 Clin Nutr doi: 10.1016/j.clnu.2012.05.013
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Vaughan VC, Hassing M-R, Lewandowski PA. Marine polyunsaturated fatty acids and cancer therapy. 2013 Br J Cancer doi: 10.1038/bjc.2012.586