Serum Phospholipid Fatty Acids And Prostate Cancer Risk: Results From The Prostate Cancer Prevention Trial, American Journal of Epidemiology, April, 2011
Men with the highest levels of one type of omega-3 (docosahexaenoic acid (DHA), found abundantly in fish oil) were two and a half times more likely to have an aggressive form of prostate cancer than men with the lowest levels:
"Docosahexaenoic acid was positively associated with high-grade disease (quartile 4 vs. 1: odds ratio (OR) = 2.50)."The curious thing ... polyunsaturated fats, including omega-3s, are easily oxidized, owing to their greater number of reactive double bonds. Once fats become oxidized in the body they can become pro-inflammatory.
"The study findings are contrary to those expected from the antiinflammatory effects of these fatty acids and suggest a greater complexity of effects of these nutrients with regard to prostate cancer risk."
Update, April 29: From the press release1 that accompanied the study:
Lead author Theodore Brasky, Ph.D, postdoctoral research fellow in the Hutchinson Center’s Cancer Prevention Program:
"We were stunned to see these results and we spent a lot of time making sure the analyses were correct. ... Our findings turn what we know — or rather what we think we know — about diet, inflammation and the development of prostate cancer on its head and shine a light on the complexity of studying the association between nutrition and the risk of various chronic diseases."Another interesting bit:
"Among the study participants, very few took fish oil supplements – The majority got omega 3s from eating fish."
More discussion at: How Much Fish Oil Is Good?