New research from a team based at the University of Illinois at Chicago has assessed the oestrogenic and anti-oestrogenic activity of Trifolium pratense L, or red clover, extracts.
Phytoestrogens, which include isoflavones, are compounds found in plants that exhibit both mild oestrogen-like and oestrogen opposing effects, depending on whether the current hormone status is low or high. They are abundant in soy and other legumes, although some of the isoflavones found in red clover are not present in soy.
Numerous studies have indicated that isoflavones can influence the metabolism and activity of oestrogens in women. Isoflavones from red clover and other botanicals, such as black cohosh, are used primarily to treat hot flushes and other symptoms of menopause. Although not as effective as hormone replacement therapy, isoflavones have become popular alternatives due to fewer side effects and greater availability.
The Illinois researchers took red clover extract, standardised to contain 15% isoflavones, and administered it to rats for 21 days in the presence and absence of oestradiol, the principal oestrogen secreted by the ovary.
The oestrogenic effects included an increase in uterine weight, vaginal cell cornification and mammary gland duct branching. Red clover produced a dose-dependent increase in uterine weight and differentiated vaginal cells at the two higher doses, but it did not stimulate cell proliferation in the mammary glands.