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The Cutting Edge

Reversing Dietary Ratio of Fatty Acids May Suppress Prostate-Cancer Growth

Altering the fatty-acid ratio found in the typical Western diet may reduce PSA levels and the growth rate of prostate cancer, a UCLA study reported in the August 2006 issue of Clinical Cancer Research. The animal-model study demonstrated that boosting consumption of omega-3 fatty acids and decreasing omega-6 fatty acids lowered an inflammatory response linked to progression of prostate tumors.

The corn oil, safflower oil and red meats that dominate the Western diet contain omega-6 fatty acids. Cold-water fish like salmon, tuna and sardines contain healthier omega-3 fatty acids. “Corn oil is the backbone of the American diet. We consume up to 20 times more omega-6 fatty acids in our diet than omega-3 acids,” says Dr. William Aronson, a professor of urology and Jonsson Cancer Center researcher.

Using a mouse model for hormone-sensitive prostate cancer, the scientists fed one group of mice a 20-percent fat diet with a healthy 1-1 ratio of omega-6 to omega-3 fatty acids. A second group of mice consumed the same diet but the fat contained mostly omega-6 fatty acids. In the first group of mice, tumor-cell growth rates dropped by 22 percent and PSA levels were 77 percent lower than in the second group.

Dr. Aronson suspects than the first diet’s increase in the omega-3 fatty acids DHA and EPA and a drop in an omega-6 acid called arachidonic acid slowed tumor progression. These three fatty acids compete for conversion into hormone-like substances called prostaglandins, which become either pro-inflammatory and spur tumor growth, or anti-inflammatory and curb growth.
Pro-inflammatory prostaglandin levels in tumors were 83 percent lower in mice in the omega-3 group than in mice in the omega-6 group, suggesting that boosting DHA and EPA may produce more anti-inflammatory prostaglandins.

Dr. Aronson currently is conducting a clinical trial with prostate-cancer patients to evaluate the protective effects of a low-fat diet with omega-3 supplements.

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