(NaturalNews) A higher dietary intake of omega-3 fatty acids may protect men from prostate cancer even if they have a genetic predisposition to the disease, researchers have found.
"We detected strong protective associations between increasing intake of long-chain omega-3 polyunsaturated fatty acids and more advanced prostate cancer," said lead researcher John S. Witte. "These fatty acids are primarily from dark fish such as salmon."
"And the decrease in risk may be even more pronounced if one has a high-risk genetic variant," he said.
In a study published in the journal Clinical Cancer Research, Witte and colleagues compared the diets and genetic profiles of 466 men suffering from aggressive prostate cancer with those of 478 healthy men of similar age and ethnic distribution. Average participant age was 65, and cancer patients were recruited an average of 4.7 months after diagnosis. Healthy controls were recruited from among men undergoing standard annual health checkups.
The researchers focused only on aggressive tumors because these represent the most dangerous form of the disease. Many men with non-aggressive, slow-growing tumors die of other causes before ever experiencing any cancer symptoms.
Researchers had all participants fill out food frequency questionnaires, classifying their intake of various kinds of fish as "never," "one to three times per month," or "one or more times per week." All men were screened for nine different mutations of the cox-2 gene. These variables were then analyzed for their relationship with prostate cancer, adjusting for other known risk factors such as smoking, obesity, family cancer history and prior prostate screening results.
The study was conducted by researchers from the Institute for Human Genetics, University of California and University of Southern California, and funded by the National Institute of Health and a dean's grant from Laval University McLaughlin.
The researchers found that men with cancer had a significantly higher intake of calories, fat and linoleic acid (an omega-6) than healthy men. They had a significantly lower intake of omega-3s, shellfish and dark fish.
Men who ate dark fish one to three times a month had a 36 percent lower chance of developing an aggressive prostate cancer than those who ate it rarely or never, while those who ate such fish once a week or more had a 63 percent lower risk.
"The strongest effect was seen from eating dark fish such as salmon one or more times per week," Witte said.
The researchers found that men with a particular cox-2 gene variant, rs4647310, had 5.5-times the risk of aggressive prostate cancer as men without that variant. This elevated risk was not seen, however, among men with a high omega-3 intake.
"Men with low intake of dark fish and the high-risk variant had a substantially increased risk of more advanced prostate cancer," Witte said.
Omega-3s are believed to decrease the risk of cardiovascular disease, cancer, and autoimmune disorders, and to improve cognitive health. The mechanisms for these benefits are not well understood, but are believed, in some cases, to be linked to reduced inflammation.
The cox-2 gene is known to play a role in prostate inflammation, a risk factor for prostate cancer.
"Previous research has shown protection against prostate cancer [by omega-3s]," Witte said, "but this is one of the first studies to show protection against advanced prostate cancer and interaction with cox-2."
Prostate cancer is the most common male cancer in the United States, and the second most common cause of male cancer death. In the United Kingdom, it is the second most common cause of overall cancer death. Obesity is one of the most well-known risk factors for the disease.
"One way men can reduce their risk of developing advanced prostate cancer, as well as risk of many other diseases, is to maintain a healthy weight," said Eric Jacobs of the American Cancer Society.