SOY ISOFLAVONES MAY CUT PROSTATE CANCER RISK IN HALF

Increased intake of soy isoflavones may cut the risk of prostate cancer by 58 percent, suggests a new study from Japan.
The research, published in the Journal of Nutrition, adds to an earlier study that claimed to be the first prospective study to report an inverse association between isoflavones and prostate cancer in Japanese men.
Over half a million new cases of prostate cancer are diagnosed every year world wide, and is the direct cause of over 200,000 deaths. More troubling, the incidence of the disease is increasing by 1.7 percent over 15 years.
The new study recruited 200 Japanese men with different stages of prostate cancer and compared their dietary intakes with 200 healthy male controls.
The intake of 12 food items was measured: tofu (soybean curd), natto (fermented soybeans), miso soup (soybean paste soup), bean curd refuse, fried bean curd, fried bean curd with vegetables, soy flour, dried bean curd, soy milk, soy sauce, green soybeans, and bean sprouts.
The researchers report that an increased intake of the soy isoflavones genistein and daidzein was significantly associated with a decreased risk of prostate cancer. The highest average isoflavone intake was associated with a 58 percent reduction in risk compared with the lowest average isoflavone intake.
They also report that the isoflavone intake was correlated with magnesium and omega-3 and omega-6 fatty acid intake, since soy products are also rich sources of these nutrients.
“On the other hand, isoflavone significantly decreased the risk of prostate cancer regardless of adjustment by PUFA, (omega-6) fatty acids or magnesium,” they said.
The researchers indicated that the results may not be generalized to other populations since the traditional Japanese diet is a rich source of dietary isoflavones.
The earlier study linking isoflavones to potential protection from prostate cancer stated that the benefits could be due to the weak oestrogenic activity of soy isoflavones, which may act to reduce testosterone levels and inhibit an enzyme involved in the metabolism of testosterone.
Corresponding author Tomoko Sonoda said, “Our group is performing the intervention study of isoflavone supplement and analyzing the interaction of estrogen related gene and isoflavone intake on prostate cancer risk.”
?In conclusion,? Sonoda continued, ?our findings indicate that isoflavones might be an effective dietary protective factor against prostate cancer in Japanese men.?

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