The Health Food Manufacturers Association (HFMA) says that a recent US study which found a link between omega-3 fish oil supplements and an increased risk of developing an aggressive type of prostate cancer is “inconclusive” and “contradicts pre-existing, robust evidence demonstrating a positive impact of fish oil supplements in this area”.
Scientists at the Fred Hutchinson Cancer Research Centre and Ohio State University discovered the link between higher blood levels of omega-3s and raised prostate cancer risk by accident while carrying out research to find out if vitamin E and selenium could help prevent prostate cancer.
Lead researcher Dr Alan Kristal said the levels of omega-3 linked to the increased cancer risk would be reached by taking just one supplement a day, or three or four meals of fish such as salmon and mackerel each week. While recommending that people continued to include some oily fish in their diet, he cautioned against supplementing with omega-3 fatty acids because of the much higher levels present.
But the HFMA says that the US study is inconclusive and contradicts the findings of numerous studies that have found health benefits from taking omega-3 supplements. It points to a 2010 meta-analysis of 31 studies published in the American Journal of Clinical Nutrition which found that high levels of fish consumption did not increase the risk of prostate cancer diagnosis. In addition, in the same meta-analysis, data from four studies found a 63% decrease in risk of death from prostate cancer for high fish consumption.
Dr Michèle Sadler, scientific adviser to HFMA, said: “This new study from Ohio State University was not designed to investigate the role of omega-3 intake and prostate cancer, rather to test the effects of selenium and vitamin E on cancer prevention and hence no firm conclusions can be drawn. This type of evidence can indicate an association, but does not demonstrate cause and effect.”
The HFMA is urging healthcare professionals to “consider the new findings alongside other robust research in this area before formulating public health recommendations”.
