Plant extracts for the treatment of menopausal women: Safe?

Abstract 

Objectives

The recently published data concerning putatively dangerous effects of classical hormone therapy resulted in increased sales of plant derived substances, which claim beneficial effects on climacteric and postmenopausal complaints and diseases. Soy and red clover extracts containing isoflavones have estrogenic effects in cell biological and animal experimental models but commercial advertisements often claim beneficial effects in mammary glands by preventing occurrence of malignancies. Black cohosh preparations are also increasingly used, and they appear to be devoid of estrogenic effects in the uterus. Their effects in the mammary gland have not yet been thoroughly studied.

Methods

Therefore, we studied the effects of genistein, the main isoflavone in soy or red clover preparations and of the black cohosh extract Cimicifuga racemosa (CR) or Actea racemosa BNO 1055 in the uterus and mammary gland of ovariectomized (ovx) rats and compared them with the effects of estradiol. Serum LH levels were also measured as an indicator of a hypothalamic/pituitary effects of the test substances.

Results

Genistein and E2, both stimulated uterine weight and several estrogen regulated genes. Lobulo-alveolar growth of 20 mammary glands as well as the expression of the nuclear protein proliferating cell nuclear antigen (PCNA, a proliferation marker) was also stimulated by E2 and genistein. The CR extract BNO 1055 was devoid of such estrogenic effects in the uterus and mammary gland. E2 and to lesser degree CR inhibited serum LH levels whereas genistein had no effects on this hormone.

Conclusions

E2 and genistein share uterotropic and mammatropic effects in ovx rats. If occurring in postmenopausal women this may endanger these organs to develop malignancies. Serum LH levels were inhibited by E2 and the CR BNO 1055 extract whereas genistein had no estrogenic effect in the hypothalamus and it is therefore unlikely that genistein inhibits climacteric complaints.

Keywords: Soy, Isoflavones, Estradiol, Black cohosh, Uterus, Mammary gland