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.
Published July 11 in the online edition of 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 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.
The increase in risk for high-grade prostate cancer is important because those tumors are more likely to be fatal.
The findings confirm a 2011 study published by the same Fred Hutch scientific team 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 Alan Kristal, Dr.P.H., the paper’s senior author and member of the Fred Hutch Public Health Sciences Division. 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, 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.
Kristal said the findings in both Fred Hutch 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 difference in blood concentrations of omega-3 fatty acids between the lowest and highest risk groups was about 2.5 percentage points (3.2 percent vs. 5.7 percent), which is somewhat larger than the effect of eating salmon twice a week, Kristal said.
The current study analyzed data and specimens collected from men who participated in the Selenium and Vitamin E Cancer Prevention Trial (SELECT), a large randomized, placebo-controlled trial to test whether selenium and vitamin E, either alone or combined, reduced prostate cancer risk. That study showed no benefit from selenium intake and an increase in prostate cancers in men who took vitamin E.
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 SELECT.
The National Cancer Institute and the National Center for Complementary and Alternative Medicine funded the research.
The mission of the National Center for Complementary and Alternative Medicine (NCCAM) is to define, through rigorous scientific investigation, the usefulness and safety of complementary and alternative medicine interventions and their roles in improving health and health care. The Center’s vision is that scientific evidence informs decision making by the public, by health care professionals, and by health policymakers regarding use and integration of these approaches.
NCCAM’s programs and organization incorporate 3 long-range goals:
- Advance the science and practice of symptom management.
- Develop effective, practical, personalized strategies for promoting health and well-being.
- Enable better evidence-based decision making regarding complementary and alternative medicine use and its integration into health care and health promotion.
More findings (Ginkgo biloba, spinal manipulation, the placebo effect on pain reduction, acupuncture, glucosamine and chondroitin, tai chi for fibromyalgia, ephedra, Kava, and Ayurvedic medicine products) here:
Well, I should be very interested in this since I use Flax oil every day and it has more omega-3 fatty acids than fish oil.
Flax is a plant with seeds filled with flaxseed oil, which contains more than twice as much omega-3 oil as fish oils. Several studies have also validated the use of essential fatty acids, such as omega-3s in fish and flaxseed oils, in relieving joint discomfort and mobility. They can also help support healthy bone density, energy endurance, a healthy cardiovascular system, and cholesterol levels.
According to one summary, the positive or negative effects of flaxoil on prostate cancer are unclear: https://www.mayoclinic.com/health/flaxseed/AN01712.
How much flax oil sold is not organic and is also not refrigerated?
“In September, 2009, reports of European flax contamination point to Canada. Seventy percent of the flax grown in Canada is exported. In 1998, Canadian regulators approved Triffid, a GM flax. Flax growers, fearing contamination of their crops, were able to have Triffid removed from approval in 2001. Though it has been illegal to grow Triffid for the last eight years, a German company has found Triffid contamination in European cereals and baked goods. The European Commission’s Rapid Alert System for Food and Feed confirmed the contamination of Canadian flax exports, and, according to a press release from the National Farmer’s Union, this discovery has devastated Canadian flax exports.” – http://www.organiclifestylemagazine.com/issue-10/gmo-contaminate-europe-flax.php
I used only Barlean’s cold pressed 100% Organic flax oil sold from a refrigerator at my local store. I suspect the results regarding flax oil are mixed because GMO flax increases prostate cancer risk, but organic refrigerated unspoiled flax does not.
What was the source of the omega-3 oils those 834 men consumed? Studies like these seem worthless to misleading without more details. I’d want to zero in on the products used by the men found with cancer and see if they might be using the same brands, eating GMO foods, consuming pesticides, radio active fish oil, etc.
Update: I no longer use flax oil. Now only olive, coconut and occasionally avocado oil.