FISH OIL STUDIES
NEWEST STUDY FROM HUTCHINSON SEATTLE
Study confirms link between high blood levels of omega-3 fatty acids and increased risk of aggressive prostate cancer
Consumption of fatty fish and fish-oil supplements linked to 71 percent higher risk
Senior author Alan Kristal, Dr.P.H., is a member of the Public Health Sciences Division at Fred Hutch.
SEATTLE – July 10, 2013 – 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 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.
Corresponding author Theodore Brasky, Ph.D., a research assistant professor at The Ohio State University Comprehensive Cancer Center, was a postdoctoral trainee at Fred Hutch when the research was conducted.
“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 canceroccurrence,” 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. Dr. Kristal has said on MSNBC that he believes men over 50 should not take fish oil.
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 group included in 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.
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A STUDY IN DIRECT CONTRAST STATED
Published on April 8, 2009 at 1:27 PM·
A new study presented in Clinical Cancer Research, a journal of the AACR (American Association for Clinical Cancer Research), shows diets high in Omega-3 EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) may decrease the risk of prostate cancer.
This link appears to be most apparent in those individuals with a genetic tendency towards developing the disease.
While there is no one, single cause of prostate cancer, there are several factors that appear to increase the risk of developing it, including diet. In the study, researchers from the University of California, San Francisco, looked at 466 men with aggressive prostate cancer and 478 healthy men, assessing their eating habits using a food frequency questionnaire. The men were also screened for a variant of a gene known as COX-2, which helps regulate inflammation in the body. A certain variant of this gene is known to increase the risk of developing prostate cancer. Note: Is here were researchers need to explore for the link?
The study shows that those men who ate dark, fatty fish one to three times per month had a 36 percent lower risk of prostate cancer as compared to those who had zero dark fish consumption. Furthermore, those who ate dark fish at least once a week had a 57% risk reduction. And, those who consumed little to no Omega-3 EPA/DHA and who also carried the specific COX-2 variant, were five times more likely to develop advanced prostate cancer. However, this association was essentially reversed with increasing consumption of Omega-3 EPA/DHA.
"This study adds to the growing research that shows that regular Omega-3 EPA/DHA consumption by men may lower their risk of developing prostate cancer,"said Ocean Nutrition Canada's Vice President, Marketing and Communications, Lori Covert. "This is definitely positive news."
According to the Canadian Cancer Society, prostate cancer is the most common cancer among Canadian men, with an estimated 24,700 men developing the disease in 2008. In the US, the American Cancer Society's Cancer Facts and Figures 2008 lists prostate cancer as the most diagnosed cancer in American men. The society also ranks prostate cancer as the second most diagnosed and the sixth leading cause of death by cancer among men globally.
In addition to helping lower the risk of developing prostate cancer, Omega-3 EPA/DHA has proven heart health benefits and may reduce the risk of esophageal and colorectal cancer. Additionally, research suggests Omega-3 EPA/DHA may improve cognitive function and symptoms of attention deficit hyperactivity disorder (ADHD), contribute to weight loss, reduce symptoms of depression, and lower the risk of stroke.
Prostate Cancer. 2013;2013:875615. doi: 10.1155/2013/875615. Epub 2013 Mar 25.
Blood level omega-3 Fatty acids as risk determinant molecular biomarker for prostate cancer.
Sorongon-Legaspi MK, Chua M, Sio MC, Morales M Jr.
Department of Preventive and Community Medicine, St. Luke's College of Medicine, Sta. Ignaciana Street, 1102 Quezon City, Philippines.
Previous researches involving dietary methods have shown conflicting findings. Authors sought to assess the association of prostate cancer risk with blood levels of omega-3 polyunsaturated fatty acids (n-3 PUFA) through a meta-analysis of human epidemiological studies in available online databases (July, 2012). After critical appraisal by two independent reviewers, Newcastle-Ottawa Quality Assessment Scale (NOQAS) was used to grade the studies. Six case control and six nested case control studies were included. Results showed nonsignificant association of overall effect estimates with total or advanced prostate cancer or high-grade tumor. High blood level of alpha-linolenic acid (ALA) had nonsignificant positive association with total prostate cancer risk. High blood level of docosapentaenoic acid (DPA) had significant negative association with total prostate cancer risk. Specific n-3 PUFA in fish oil, eicosapentaenoic acid (EPA), and docosahexaenoic acid (DHA) had positive association with high-grade prostate tumor risk only after adjustment of interstudy variability. There is evidence that high blood level of DPA that is linked with reduced total prostate cancer risk and elevated blood levels of fish oils, EPA, and DHA is associated with high-grade prostate tumor, but careful interpretation is needed due to intricate details involved in prostate carcinogenesis and N-3 PUFA metabolism.