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.
A study 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 (1). Average participant age was 65, and cancer patients were recruited an average of 4.7 months after diagnosis. 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, known to play a role in prostate inflammation, a risk factor for prostate cancer.
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 (e.g., salmon) one to three times a month had a 36% lower chance of developing 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% lower risk.
The researchers found that men with a particular cox-2 gene variant 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.
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.