Study Confirms Link Between High Blood Levels of Omega-3 Fatty Acids and Increased Risk of Aggressive Prostate Cancer

Key Points

  • High concentrations of EPA, DPA, and DHA are associated with a 71% increased risk of high-grade prostate cancer, a 44% increased risk of low-grade prostate cancer, and a 43% increase in risk for all prostate cancers.
  • The findings confirm the results of previous studies and suggest that patients and doctors should consider the potential risks of nutritional supplements.
  • Whether omega-3 fatty acids play a detrimental role in prostate cancer prognosis is unclear.

A second large, prospective study by scientists at Fred Hutchinson Cancer Research Center has confirmed the link between high blood concentrations of omega-3 fatty acids and an increased risk of prostate cancer.

Study Details

Published online in the Journal of the National Cancer Institute, the latest findings indicate that high concentrations of EPA, DPA, and DHA—the three anti-inflammatory and metabolically related fatty acids derived from fatty fish and fish-oil supplements—are associated with a 71% increased risk of high-grade prostate cancer The study also found a 44% increase in the risk of low-grade prostate cancer and an overall 43% increase in risk for all prostate cancers. The difference in blood concentrations of omega-3 fatty acids between the lowest and highest risk groups was about 2.5% (3.2% vs 5.7%).

The group included in the this analysis consisted of 834 men who had been diagnosed with incident, primary prostate cancers (156 were high-grade cancer) along with a comparison group of 1,393 men selected randomly from the 35,500 participants in the SELECT trial.

Role of Omega-3 Fatty Acids Confirmed

The findings confirm a 2011 study published by the same team at Fred Hutchinson that reported a similar link between high blood concentrations of DHA and a more than doubling of the risk for developing high-grade prostate cancer. The latest study also confirms results from a large European study.

“The consistency of these findings suggests 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 authors wrote.

“We’ve shown once again that use of nutritional supplements may be harmful,” said senior author Alan Kristal, DrPH, of the Fred Hutchinson Public Health Sciences Division. Dr. Kristal also noted a recent analysis published in the Journal of the American Medical Association that questioned 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, PhD, Research Assistant Professor at The Ohio State University Comprehensive Cancer Center. “It’s important to note, however, that these results do not address the question of whether omega-3s play a detrimental role in prostate cancer prognosis,” he said.

Questions Remain

Dr. Kristal said the findings in both Fred Hutchinson studies were surprising because omega-3 fatty acids are believed to have a host of positive health effects based on their anti-inflammatory properties. Inflammation plays a role in the development and growth of many cancers.

It is unclear from this study why high levels of omega-3 fatty acids would increase prostate cancer risk, according to the authors, however the replication of this finding in two large studies indicates the need for further research into possible mechanisms. One potentially harmful effect of omega-3 fatty acids is their conversion into compounds that can cause damage to cells and DNA, and their role in immunosuppression. Whether these effects impact cancer risk is not known.

The National Cancer Institute and the National Center for Complementary and Alternative Medicine funded the research.

The content in this post has not been reviewed by the American Society of Clinical Oncology, Inc. (ASCO®) and does not necessarily reflect the ideas and opinions of ASCO®.


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