Eating a lot of oily fish or taking potent fish oil supplements may increase the risk of developing prostate cancer, new research suggests.

Moreover, marine sources of omega-3 fatty acids may also raise the risk for aggressive prostate cancer, according to the study by scientists at the Fred Hutchinson Cancer Research Center in Seattle.

"These anti-inflammatory omega-3s were associated with a 43 percent increased risk for prostate cancer overall, and a 71 percent increased risk in aggressive prostate cancer," said study lead author Theodore Brasky. Aggressive prostate cancer is often fatal, he added.

Omega-3 fatty acids, found in fish such as salmon, trout and fresh tuna and in fish oil capsules, are widely reputed to have health benefits because of their anti-inflammatory properties.

But this new research, published online in the Journal of the National Cancer Institute, confirms previous damaging evidence.

Why are these omega-3 fatty acids associated with prostate cancer? "That's the million dollar question," Brasky said.

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