Fish Oil Causes Prostate Cancer? Don't Believe the Media Hype
By David Seaman, DC, MS, DABCN
There has recently been a surge in media coverage regarding a study that allegedly examined the effects of fish oil supplementation on prostate cancer expression. But quite to the contrary, the subjects in this study were not supplemented with fish oil or put on a fish-rich diet, which means that it is completely inappropriate to suggest fish-oil supplementation causes prostate cancer.
As the study authors explained, they did a blood test on 834 subjects who developed prostate cancer in the SELECT Trial and measured fatty acids in plasma phospholipids. After a blood draw, the fatty acids were measured as a percentage of total fatty acids in plasma phospholipids, and included omega-3, omega-6 and trans-fatty acids such as eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). While the .04 percent increase in EPA levels and the .1 percent increase in DHA levels in prostate-cancer patients may be statistically significant, the clinical relevance of such small differences remains unknown and was not discussed in the study. Despite this unknown, news reports irresponsibly suggested that consuming fish and fish oil supplements may be a cause of prostate cancer and that men should be careful not to eat too much fish.
The more appropriate conclusion would be that since controls (study subjects without prostate cancer) and prostate cancer patients have nearly identical plasma phospholipid levels of omega-3 fatty acids, it is not likely that an association between fatty acids and prostate cancer can be identified in this study. Other dietary and lifestyle factors are likely to be involved. Consider that prostate cancer is rare in Inuit Eskimos, who consume a traditional diet that includes extremely large amounts of omega-3 fatty acids.
Unfortunately, the media scare about eating fish and taking fish oil has been pervasive. Why would the media be so irresponsible? It is either due to ignorance – or perhaps a new prostate cancer treating/preventing medication may be in the works. This notion may not be so far-fetched. Consider that statins are now often recommended as a preventive strategy for people with total cholesterol below 200 mg/dl.
David Seaman, MS, DC, DACBN, is the author of Clinical Nutrition for Pain, Inflammation and Tissue Healing. He has a master's degree in nutrition from the University of Bridgeport, Conn., and lectures on nutrition.