High Omega-3 Levels Double Prostate Cancer Risk

SEATTLEMen who have high blood percentages of omega-3 fatty acids may have more than double the risk of developing prostate cancer compared to men with the lowest levels of docosahexaenoic acid (DHA), according to a new study published in the American Journal of Epidemiology.

Researchers at Fred Hutchinson Cancer Research Center conducted a nationwide study of 3,400 men to investigate the association of dietary fats and prostate cancer risk. They found with the highest blood percentages of DHA have 2.5 times the risk of developing aggressive, high-grade prostate cancer compared to men with the lowest DHA levels.

The study also found men with the highest blood ratios of trans fatty acids had a 50-percent reduction in the risk of high-grade prostate cancer. Neither of the fats was associated with the risk of low-grade prostate cancer risk. Omega-6 fatty acids were not associated with prostate cancer risk, and none of the fats were associated with the risk of low-grade prostate cancer.

"Our findings turn what we knowor rather what we think we knowabout 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," they said. "Overall, the beneficial effects of eating fish to prevent heart disease outweigh any harm related to prostate cancer risk. What this study shows is the complexity of nutrition and its impact on disease risk, and that we should study such associations rigorously rather than make assumptions."

The researchers said the mechanisms behind the impact of omega-3s on risk of high-grade prostate cancer are unknown. In addition to inflammation, omega-3 fats affect other biologic processes that may play a greater role in the development of certain prostate cancers.