Dr. David Katz presents a comprehensive and interesting analysis of the latest scary study prompted by the headline: Fish Oil Causes Cancer. His article also discusses the evidence of the benefits of fish oil based on other studies as well as the epidemiological studies that support a beneficial effect.
I find it most interesting his suggestion of the role of the anti-inflammatory effects of omega-3 fatty acids – perhaps, he says, that too little inflammation could exacerbate the promotion of cancer in this way. Fish oils are claimed to be highly anti-inflammatory and the immune surveillance system (if it exists) works to control cancer cells by the inflammatory process as well as other mechanisms of the immune system. As Dr. Katz says: “Immune function is all about balance”.
I did my research on omega-3 and omega-6 fatty acids and breast cancer (in rats), and we found no significant differences in breast cancer occurrence between the groups, either at high or low levels in the diet. We were quite surprised at these results and repeated the study and found the same occurrences. But we found no increase in the fish oil groups compared to the corn oil groups.
So the plot thickens on the diet and cancer connection. As is often stated, one study is not the end-all and should be repeated. Scary headlines do not belong in diet and nutrition studies – they do more harm than good and can be so misleading. I have read two opinions of physicians who continue to recommend eating fish in foods and supplements until further studies can clarify what is actually going on here. Ditto!