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The study was published online July 10 in the Journal of the National Cancer Institute.
Dietary supplement industry associations the Council for Responsible Nutrition (CRN; Washington, DC) and the Global Organization for EPA and DHA Omega-3s (GOED; Salt Lake City) are speaking out against a new scientific analysis linking omega-3 plasma levels and risk of prostate cancer. The study was published online July 10 in the Journal of the National Cancer Institute.
Researchers analyzed existing data from the Selenium and Vitamin E Cancer Prevention Trial (SELECT), which was a large-scale National Institutes of Health clinical study conducted in men to determine whether selenium and/or vitamin E could help prevent prostate cancer. Initial SELECT results were first reported in 2008.
Taking SELECT data, the Journal of the National Cancer Institute researchers looked at plasma data from 834 of the men in the SELECT trial diagnosed with prostate cancer. Researchers said that men with the highest levels of omega-3 fatty acids in their plasma had the highest increased risk of low-grade (a 44% increase), high-grade (a 71% increase), and total (a 43% increase) prostate cancer. “This study confirms previous reports of increased prostate cancer risk among men with high blood concentrations of [omega-3 fatty acids],” they concluded.
CRN, however, pointed out what it says are the analysis’s numerous shortcomings. For one, it says, the SELECT trial’s primary endpoint was not to test the effects of omega-3. There is no evidence documented that the SELECT subjects took omega-3 supplements.
Both CRN and GOED questioned the significance of the study’s findings. “The difference in mean blood plasma phospholipid fatty acids blood level for omega-3s was 4.66% in the combined cancer group versus 4.48% in the control. They are basing their results on just [circa] 0.2% difference in omega-3 levels,” GOED stated.
Both groups also pointed out that plasma omega-3 levels are not a good indicator of long-term effects because plasma levels of omega-3 fatty acids spike quickly after supplementation and can quickly decline again a few hours later. The groups also highlight numerous studies that conversely show omega-3 intake associated with decreased risk of prostate cancer.
“If the findings [of this latest analysis] were true, then prostate cancer would be rampant in any country with high seafood consumption (Scandinavia, Japan, etc.) and, conversely, low-level consumption should be protective. Clearly this is not the case,” GOED said.
Duffy MacKay, ND, CRN’s vice president, scientific and regulatory affairs, added, “The numerous benefits of omega-3 fatty acids from foods (like salmon and sardines) and dietary supplements are well-established for men and women in all stages of life-and this new study does not change those recommendations about the importance of this nutrient. Hundreds of studies over the past two decades have shown omega-3 fatty acids to have positive effects associated with cardiovascular health, perinatal health, inflammation, cognitive function, or cancer.
Further, the researchers were quick to blame dietary supplements even though there is no evidence that anybody in this study took fish oil dietary supplements. In fact, the study demonstrates no cause and effect; it can only purport to show an association between higher plasma levels of omega-3 fatty acids and those whom the researchers advise had an increased rate of prostate cancer.”