Chemoprevention of breast cancer, proteomic discovery of genistein action in the rat mammary gland.
Journal of Nutrition, 2005 December, 135:2953S-2959S
The soy isoflavones genistein seems to protect against mammary cancer according to a research by the University of Alabama and led by C Rowell. Tests with rats showed that consumption of genistein during the prepubertal period only and the combined prepubertal and adult period suppresses chemically induced mammary cancer. Genistein exposure of the rats only during adulthood did not result in protection.
Short-term soy and probiotic supplementation does not markedly affect concentrations of reproductive hormones in postmenopausal women with and without histories of breast cancer.
The Journal of Alternative and Complementary Medicine, December 2005, 11(6):1067-74
Epidemiological studies show that dietary isoflavones reduce the risk of breast cancer. This effect of isoflavones may be partially caused in part by effects on endogenous hormone levels. The purpose of this study was to investigate the effect of the consumption of probiotic bacteria on the biological effect of isoflavones. Twenty postmenopausal breast cancer survivors and twenty healthy postmenopausal women received different diets containing isolated soy protein or isolated milk protein and with or without probiotic capsules (with Lactobacillus acidophilus and Bifidobacterium. The researchers found that hormone levels were not affected by soy or probiotic supplements. There was no influence of equol producer status and probiotics did not influence the effects of soy consumption. Soy protein tended to decrease SHBG compared to milk protein diets. Moderate consumption of isoflavone containing soy protein and consumption of the probiotic capsules did not significantly alter reproductive hormone concentrations regardless of equol producer status.
Effects of some natural 5-hydroxy-isoflavones on cultured human endothelial cells in presence and absence of hydrogen peroxide
Journal of Pharmacy and Pharmacology, January 2006, 58(1):101-5
People who consume a lot of isoflavones have lower rates of prostate and breast cancers, osteoporosis and cardiovascular diseases. The effects of isoflavones have been explained by their estrogenic and antioxidant properties. Isoflavones are also available as supplements causing a potential danger of over consumption, since some isoflavones have potentially toxic effects (cytostatic or cytotoxic). The potential cytotoxic risk and antioxidant effects of natural 5-hydroxy-isoflavones were determined on cultured human endothelial cells, which were treated with the oxidant hydrogen peroxide. Very high concentrations of the isoflavones genistein and biochanin A, which have a free 7-OH group, were toxic to the human endothelial cells. However, normal consumption of isoflavones could not cause damage to the human vascular endothelium since toxic levels are believed to be unreachable in vivo..
Soy Isoflavones Alter Expression of Genes Associated with Cancer Progression, Including Interleukin-8, in Androgen-Independent PC-3 Human Prostate Cancer Cells
Journal of Nutrition, January 2006, 136(1):75-82
The high intake of soy isoflavones in Asia has been associated with lower incidence of prostate cancer. The main soy isoflavones are genistein and daidzein. The purpose of this study was to investigate the action of soy isoflavones on PC3 prostate cancer cells. More specifically the effect of soy isoflavones on prostate cell growth and gene expression was measured. Soy isoflavones decreased the viability of prostate cells and inhibited DNA synthesis. Soy isoflavones changed the expression of 75 genes (28 were upregulated and 47 were downregulated). The study concluded that soy isoflavones inhibits the growth of PC3 prostate cancer cells through modulation of cell cycle progression and the expression of genes involved in cell cycle regulation, metastasis and angiogenesis.
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