Fish oils may raise prostate cancer risks, study confirms

http://www.nbcnews.com/health/fish-oils-may-raise-prostate-cancer-risks-study-confirms-6C10597283

Fish oils may raise prostate cancer risks, study confirms
Maggie Fox, Senior Writer NBC News
14 hours ago

Everyone knows that fish oil is good for you, right? It’s a rich source of omega-3 fatty acids, which are marketed to reduce the risk of just about everything from heart disease to Alzheimer’s.

But a startling study shows men who have the highest levels of these compounds – the kinds found in fish but not in vegetable sources -- have a higher risk of prostate cancer. Men with the very highest levels had a 71 percent higher risk of high-grade prostate cancer – the kind most likely to spread and kill, they report in the Journal of the National Cancer Institute.

It might be a sign that popping a pill is not only possibly a waste of money – it might be downright dangerous. And eating fish too often might be, also.

“These fish oil supplements in which some men getting mega, mega doses…in our opinion that is probably a little bit dangerous,” said Theodore Brasky of Ohio State University Medical Center, who worked on the study with a team from the Fred Hutchinson Cancer Research Center in Seattle.

The same team published a study in 2011 that showed men with the highest levels of one omega-3 fatty acid called docosahexaenoic acid, DHA for short, had double the risk of high-grade prostate cancer. Other studies have had similar findings.

To try to confirm their work, the team looked at data from a different prostate cancer trial called SELECT, for Selenium and Vitamin E Cancer Prevention Trial. That study showed 17 more cases of prostate cancer among men who took vitamin E alone for about five years compared to men taking placebos.

The effect was even stronger when they looked at omega-3 fatty acids – specifically, the kinds found in fish oil as compared to those found in vegetable oils.

Brasky’s team looked at 834 of the men in the SELECT trial who developed prostate cancer, and 1,393 randomly chosen others from the trial who didn’t have cancer. They divided the men into four groups based on their blood levels of three omega-3 fatty acids – EPA, DPA and DHA.

Those with the highest blood levels had a 71 percent higher risk of high-grade prostate cancer, compared to those with the lowest levels. Overall, their risk of any kind of prostate cancer was 44 percent higher.