High Omega-3's May Boost Risk of Aggressive Prostate Cancer

The trial involved nearly 19,000 men age 55 and older, but the data for the analysis came from a subset of more than 3,400 of the study participants, half of whom developed prostate cancer during the course of the study and half of whom did not. Phospholipid fatty acids were extracted from serum of the patients, and concentrations of ω-3, ω-6, and trans-fatty acids (TFAs) were expressed as proportions of the total.

The researchers found that men with the highest blood percentages of DHA--an inflammation-lowering ω-3 fatty acid commonly found in fatty fish--have two-and-a-half-times the risk of developing prostate cancer compared to men with the lowest DHA levels. The study also found that men with the highest blood ratios of TFAs--linked to inflammation and heart disease and abundant in processed foods that contain partially hydrogenated vegetable oils--had a 50% reduction in the risk of high-grade prostate cancer. The researchers also found that ω-6 fatty acids--found in most vegetable oils and linked to inflammation and heart disease--were not associated with prostate cancer risk. The study was published ahead of print on April 24, 2011, in the American Journal of Epidemiology.

"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,” said lead author Theodore Brasky, PhD, and colleagues in the Public Health Sciences Division. "Besides inflammation, ω-3 fats affect other biologic processes. It may be that these mechanisms play a greater role in the development of certain prostate cancers. This is certainly an area that needs more research.”

"Overall, the beneficial effects of eating fish to prevent heart disease outweigh any harm related to prostate cancer risk,” added Dr. Brasky. "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.”

Related Links:
Fred Hutchinson Cancer Research Center