Eating Fatty Fish May Slash Risk Of Prostate Cancer

New York, June 1, 2001 (PSA Rising) -- Eating fatty fish like salmon, sardines, herring and mackerel could reduce the risk of prostate cancer by a third, according to a report in June 2 issue of The Lancet.

Essential fatty acids -- especially omega-3 fatty acids contained in large amounts in fatty fish -- have already been proven to inhibit the growth of prostate cancer cells.

Paul Terry and colleagues from the Karolinska Institute, Stockholm, Sweden, followed over 6,000 Swedish men age 55 for up to thirty years to see whether eating fatty fish would reduce risk of prostate cancer.

The men were asked about diet, smoking habits, alcohol drinking and physical activity. The men were followed up between 1967 and 1997. Researchers calculated number of cases of prostate cancer and of deaths caused by the disease by consulting the Swedish National Cancer Register and National Death Register.

During a 30-year follow-up, 466 men were diagnosed with prostate cancer, and 340 of these men died. The men who ate no fish had a twofold to threefold higher risk of prostate cancer than those who ate moderate or high amounts.

Paul Terry says: "Our study was done in Sweden, a country with traditionally high consumption of fatty fish from Northern (cold) waters, which contain high amounts of omega-3 fatty acids."

"Since few dietary and other modifiable factors seem to be associated with lower risk of prostate cancer, our results may indicate an important means by which this disease might be prevented."

Essential fatty acids in fish inhibit the growth of prostate cancer cells in the lab dish and in experimental animals. Earlier studies have found that higher the concentration of fatty acids in a man's bloodstream, the lower his risk of prostate cancer.

But studies of fish consumption and prostate cancer based on large populations are scarce, the authors state. "Furthermore, such studies often measure only a small variation in fish consumption and lack controls for confounding variables. Finally, the type of fish studied is often not described."

"Only fish high in omega-3 fatty acids are likely to lower the risk of prostate cancer." People in Sweden traditionally eat a lot of fatty fish from Northern (cold) waters, such as salmon, herring, and mackerel, which contain high amounts of omega-3 fatty acids, the authors say.

"Our results support the hypothesis that fatty fish consumption lowers the risk of prostate cancer, possibly through inhibition of arachidonic acid-derived eicosanoid biosynthesis, the authors say. Results of a cross-sectional study in 16 regions of Europe "showed greatly increased (threefold to fourfold) plasma concentrations of eicosapentaenoic acid (EPA) in people from Sweden and Denmark who consumed high amounts of fatty fish."

EPA competes with arachidonic acid as a substrate for cyclo-oxygenases. High concentrations of EPA can lead to important changes in relative concentrations of tumor growth enhancing prostaglandins.

To control for genetic bias, this study used The Swedish Twin Registry, which is supported by grants from the Swedish Cancer Society, the John D and Catherine T MacArthur Foundation, and the Swedish Council for Planning and Coordination of Research (FRN).

Fatty fish consumption and risk of prostate cancer, by Paul Terry, Paul Lichtenstein, Maria Feychting, Anders Ahlbom, Alicja Wolk The Lancet, 2nd June 2001; registration may be required but this article is FREE).

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Omega-3 Fatty Acids MAGGIE B. COVINGTON, M.D., University of Maryland School of Medicine, Baltimore, Maryland American Family Physician® >Vol. 70/No. 1 (July 1, 2004)