The two classes of polyunsaturated fatty acids that influence prostate cancer are omega-6 (n-6) and omega-3 (n-3) fatty acids. Pro-inflammatory omega-6 fatty acids stimulate prostate cancer cell growth, while anti-inflammatory omega-3 fatty acids inhibit this growth. Omega-6 fatty acids are found in vegetable, corn, safflower, and cottonseed oil. Omega-3 fatty acids are found in flaxseed, fish oil and krill oil.
A new study by researchers at UCLA, published in Clinical Cancer Research has found that the key to promoting prostate health may lie in maintaining a healthy ratio of n-6 to n-3 fatty acids in your body.
In the study, two groups of 15 mice were fed diets similar in calories with 20% calories from protein, 60% from carbohydrate, and 20% from fat. The only differences between the two groups was the fat content. The n-6 group had an n-6 to n-3 ratio of 26:1 while the n-3 group had an n-6 to n-3 ratio of 1:1. Two weeks after the study started, the mice were injected with prostate cancer cells and continued to be fed for eight weeks.
At the end of eight weeks, researchers found that tumor growth rates, final tumor volumes, and prostate cancer marker levels were reduced in the n-3 group compared to the n-6 group. In the n-3 group, tumors had both a 22% decreased rate of cell division and an increased rate of cell death. What’s more, n-3 group tumors had reductions in inflammatory proteins called PGE2 and COX-2 by 83% and 30%, respectively, both of which have been implicated in prostate cancer.
The researchers concluded, “dietary intervention trials incorporating omega-3 supplements (DHA and EPA) with reduced dietary omega-6 fatty acid . . . may play an important role in primary and secondary prostate cancer prevention.”
Kobayashi N. Effect of Altering Dietary n-6/n-3 Fatty Acid Ratios on Prostate Cancer Membrane Composition, Cyclooxygenase-2, and Prostaglandin E2. Clin Cancer Res 2006 12: 4662-4670.