Eating a lot of oily fish or consuming omega supplements may not be good for a man’s health. New research reveals that males with high blood concentrations of omega-3 fatty acids are at a higher risk of developing prostate cancer.

The finding comes from a large prospective study published in the Journal of the National Cancer Institute.

A 71 percent increased risk of high-grade prostate cancer and a 43 percent increase for all prostate cancers were associated with high concentrations of EPA, DHA, and DPA.

These results are consistent with a 2011 study carried out by the same research team which found that high concentrations of DHA more than doubled the risk of high-grade prostate cancer.

The researchers were shocked to find that higher blood levels of omega-3 fatty acids, usually promoted as good for the heart, were associated with a higher risk of aggressive prostate cancer.

The consistency of these findings could mean that “these fatty acids are involved in prostate tumorigenesis and recommendations to increase long-chain omega-3 fatty acid intake, in particular through supplementation, should consider its potential risks.”

The paper’s senior author and member of the Fred Hutch Public Health Sciences Division, Alan Kristal, Dr.P.H, said: “we’ve shown once again that use of nutritional supplements may be harmful.”

Theodore Brasky, Ph.D., a research assistant professor at The Ohio State University Comprehensive Cancer Cente, added, “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. 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.”

Dr. Iain Frame, director of research at Prostate Cancer UK (resource no longer available at, says men reading about the results of this research should not panic about their omega-3 intake. Dr. Frame says: “Omega 3, such as is found in oily fish, has been the focus of a large amount of research in recent years, the majority of which points to it having wide-ranging health benefits when eaten as part of a balanced diet…”

“Much larger and more complex studies will need to take place before we will fully understand how the risks of a diet high in Omega 3 balance against those benefits.”

Dr. Frame adds:

“Therefore, we would not encourage any man to change their diet as a result of this study, but to speak to their doctor if they have any concerns about prostate cancer.”

Dr. Kristal’s study compared the blood level concentrations of omega-3 fatty acids in 834 men who had been diagnosed with prostate cancer with samples from 1,393 men from the Selenium and Vitamin E Cancer Prevention Trial (SELECT).

The lowest risk group for developing prostate cancer had a 3.2 percent blood level concentration of omega-3 fatty acids, compared to 5.7 percent in the high risk group.

The results may come as a surprise to some, considering the number of positive health benefits that are associated with omega-3 fatty acids.

It remains uncertain why high concentrations of these fatty acids are associated with a heightened risk of prostate cancer.

Researchers say it is possible that omega-3 fatty acids are harmful because of they convert into compounds that can damage cells and DNA.

In conclusion, the finding suggests that high levels of omega-3 fatty acids can increase a man’s risk of developing prostate cancer.