Men who had high levels of selenium, multi-vitamins, vitamin E and soy isoflavones had lower risk for prostate cancer than men with low levels of these nutrients in two new studies. Soy isoflavones slowed the growth of prostate-cancer cells in a third new study.
In the selenium study, researchers measured the blood fluid (serum) levels of selenium in 724 men with prostate cancer and in 879 healthy men of the same age who entered the study at the same time, and followed up for eight years. Scientists found that men who had higher selenium levels who also reported taking multi-vitamins had 39% lower risk for prostate cancer than men with the lowest selenium levels. Doctors also found that men with higher selenium levels who reported taking more than 28 IU of vitamin E per day had 42% lower risk for prostate cancer than men with the lowest selenium levels. Men with higher selenium levels who did not take vitamin E or multi-vitamins did not have significantly lower prostate cancer risk than those with low selenium levels.
In the soy isoflavone study published in the March 2007 issue of Cancer Epidemiology Biomarkers & Prevention, researchers examined the diets of 43,509 Japanese men aged 45 to 74 (average age 57) and followed up for nine years. During the study period, 307 men developed prostate cancer. Doctors found that men who took 32.8 mg or more of soy isoflavones per day had 40% lower risk for prostate cancer compared to men who took less than 13.2 mg per day. When doctors analyzed men aged 60 or older, leaving out the younger men, those who took 32.8 mg or more of soy isoflavones per day had 49% lower risk for prostate cancer compared to men who took the least soy isoflavones.
In a test tube study published in the April 2007 issue of the Journal of Nutrition, scientists reported a soy isoflavone concentrate cut the growth of malignant prostate-cancer cells, known as lymph node carcinoma prostate or LNCaP, and helped regulate the gene activity that influences cancer growth.