By Jeffrey Kopman
Put on your fishing hat, grab your rod, and get your tackle box ready because it's time to go fishing for the truth about omega-3 fatty acids. These acids, commonly found in fish, have shown benefits for heart disease, autoimmune diseases, and breast cancer, but scientists have now also found a link between fish oil supplements, childhood allergies, and prostate cancer, according to a study from the Fred Hutchinson Cancer Research Center published in the Journal of the National Cancer Institute and another study from the Chalmers University of Technology in Sweden published in the journal PLOS ONE.
In 2011, researchers from the Fred Hutchinson Cancer Research Center in Seattle discovered that men with high levels of DPA -- an anti-inflammatory acid found in fatty acids and fish-oil supplements -- were twice as likely to have prostate cancer than men with lower levels. The same researchers now report that they have successfully replicated this finding.
"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, in a press release.
The current study observed 834 men with prostate cancer and a control group of 1,393 randomly selected men.
In addition to the previous discovered link with DPA, Dr. Kristal and his team found a link between prostate cancer and two other anti-inflammatory acids found in fish-oil supplements: EPA and DHA. These fatty acids were associated with a 71 percent increase in risk of high grade prostate cancer and a 44 percent increase in risk of low-grade prostate cancer. The overall increase for prostate cancer was 43 percent.
The confirmation of previous results is important, but researchers admit that further research is needed to identify the mechanisms that link fish oil and prostate cancer.
"These studies find correlations, but not always causations," warned Ashley Barrient MEd, LPC, RD, LDN, at Loyola University Medical Center in Maywood, Ill., who was not affiliated with the study. "More research is needed [to show causation]."
Fish Oils and Childhood Allergies
Similar to the connection between fish oils and prostate cancer, a connection has been found between fish oils and allergies in children, although the mechanism is once again unknown, according to the study from the Chalmers University of Technology in Sweden.
Researchers used a sample of birth records for 129 13-year old children to test the impact of fatty acids in cord blood at birth on allergy risk later in childhood.
Of the 129 children used, 44 had been diagnosed with respiratory allergies, and another 36 had chronic skin rashes. These children had higher proportions of omega-3 and omega-6 unsaturated fatty acid levels in the blood samples taken at birth than the 48 children who did not report any allergies.
Researchers theorized that the mechanism for this connection could be due to a weakened development of the infant's immune system caused by the omega-3 and omega-6 lipids. Future research will need to confirm the link and mechanism for this reaction.
Are Omega-3's Worth the Risk?
Depending on your risk factors for certain conditions, omega-3's might still be an important part of your diet. But a few types of people shouldn't rush to load up on fish oil supplements, like men who are already at a high risk for prostate cancer.
"We [also] don't want pregnant women and children to eat a lot of fish because of mercury," Barrient added.
"[Supplement therapy] is very individualized," said Barrient. "A supplement should be given under doctor supervision because doctors can look at your risk factors for prostate cancer or heart disease before recommending anything."
Barrient warns that taking supplements or eating fish in excess could cause problems in areas other than the one patients are trying to address.
On the other hand, individuals at high risk for heart disease should certainly consider adding supplements to their diet. Several studies have shown that omega-3 fatty acids are good for your heart and can reduce the risk of heart attack and stroke.
But supplements aren't always the answer. Some people will benefit more from eating the fish itself than just omega-3 supplements.
"For the average person with a family history of cardiovascular disease, I strictly recommend the whole food source, not just supplements," said Barrient. "The American Heart Association recommends 2-3 servings of fish a week. [But] someone with really high triglycerides and more severe coronary artery disease might need supplementation."
"Omega-3 Fatty Acids Might Offer More Risk Than Reward" originally appeared on Everyday Health.