Why Men Should Lay Off Fish Oil Supplements

A new study is leaving some men on the edge, after it noted that eating too much food naturally high in omega-3 fatty acids such as salmon, or taking fish oil supplements, can actually leave them at a higher risk of prostate cancer.

A study published Wednesday in the Journal of the National Cancer Institute found that that men with high concentrations of omega-3 fatty acids in their blood are more likely to develop prostate cancer, the most common cancer affecting men.

Men who took fish oil supplements or consumed an excessive amount of omega-3 fatty acid rich food had higher concentrations of EPA, DPA and DHA - the three anti-inflammatory and metabolically related fatty acids derived from fatty fish and fish-oil supplements. They are associated with a 71 percent increased risk of high-grade prostate cancer. 

The study also found a 44 percent increase in the risk of low-grade prostate cancer and an overall 43 percent increase in risk for all prostate cancers.

 "We've shown once again that use of nutritional supplements may be harmful," said Alan Kristal, Dr.P.H., the paper's senior author and member of the Fred Hutch Public Health Sciences Division. Kristal also referenced a recent study published in the Journal of the American Medical Association that investigated the benefit of omega-3 supplementation for cardiovascular diseases. The analysis, which combined the data from 20 studies, found no reduction in all-cause mortality, heart attacks or strokes. 

"What's important is that we have been able to replicate our findings from 2011 and we have confirmed that marine omega-3 fatty acids play a role in prostate cancer occurrence," said corresponding author Theodore Brasky, Ph.D., a research assistant professor at The Ohio State University Comprehensive Cancer Center who was a postdoctoral trainee at Fred Hutch when the research was conducted. "It's important to note, however, that these results do not address the question of whether omega-3's play a detrimental role in prostate cancer prognosis," he said.