Soy and red clover extracts contain high concentrations of isoflavones, particularly of genistein, which bind to both estrogen receptors α and ß (ERα and ERß). Lifelong nutrition rich in soy proteins or soy protein isolates appear to exert positive effects on certain health aspects including the development of mammary cancer but the beneficial effects become questionable when soy/isoflavone-rich nutrition starts in later adult life. Stimulatory effects on mammary cancer cell growth in vitro and in animal experiments were reported. Mammary gland safety studies in climacteric/postmenopausal women who initiated isoflavone-rich intake for climacteric/postmenopausal complaints/diseases are inconclusive. A 5-year-lasting intake of 150 mg of isoflavones resulted in the development of endometrial hyperplasia in 3.37% of the women in a large placebo-controlled study; such effect was not observed in the placebo group. To the best of our knowledge a total of 28 placebo-controlled studies have been published hitherto in which 22 demonstrated no better effect than placebo on climacteric complaints. On the other hand, most animal experimental and clinical studies indicate a mild antiosteoporotic effect of soy/isoflavones. Taken collectively, soy/red clover/isoflavones appear to have mild estrogenic effects with all advantages and disadvantages of a low dose of estradiol-17ß.
Extracts of Cimicifuga racemosa (Black cohosh) have since long been successfully tested in clinical trials on menopausal symptoms. So far 5 double-blind placebo-controlled studies have been conducted, 4 of which showed positive results on climacteric complaints. The most recent studies indicate that Black cohosh extracts have no effects in the mammary gland and in the endometrium but mild antiosteoporotic effects have been reported. The active compounds in Cimicifuga racemosa are not yet identified.
01 - 05 Apr 2006
European Society of Endocrinology