Over 150 common herbs were tested to see how well they bind to human breast cell receptors to compete with the female hormones. Of the common plants studied, the most estrogenic were soy bean (Soya glacine), licorice (Glycyrrhiza glabra), red clover (Trifolium pratense), thyme (Thymus vulgaris), turmeric (Curcuma longa), and hops (Humulus lupulus). Bloodroot (Sanguinaria canadensis), yucca (Yucca species), and yellow dock (Rumex crispus) also showed significant hormonal activity. Since the ability to bind receptors does not mean that herbs act hormonally in the body, they were further tested by measuring hormones in women's saliva. (Saliva is a highly filtered version of serum so it gives a good idea of what hormones are in the blood.) Estrogenic herbs, especially soymilk, were active. Dong quai (Angelica sinenis) produced very low estradiol and may suppress this type of estrogen. Some herbs reputed to be hormonal, such as flaxseed (Linum usitatissimum) and black cohosh (Actaea racemosa aka. Cimicifuga racemosa), didn’t change saliva hormones at all. However, they may work in other ways, perhaps as estrogen precursors. (Flaxseed’s estrogenic compounds are created by flora in the bowel.) Also, false results can occur when substances such as tannins are present.
The six most potent common herbs to bind progesterone receptors were oregano (Origanum vulgare), verbena (Verbena species), turmeric, thyme, red clover, and damania (Turnera difussa). Herbs with anti-progesterone activity were red clover, licorice, goldenseal, pennyroyal (Mentha pulegium), nutmeg (Myristica fragrans), and mandrake (Podophyllum peltatum). Most progesterone-binding herbs were not active or were anti-progestogenic in the body (such as pennyroyal). Wild yam (Dioscoria villosa) increased progesterone receptor binding in 20-30% of women, but appeared to suppress progesterone. Researchers concluded that diosgenin, the yam compound used to synthesize progesterone, “did not convert to progesterone in the body.”
In AHA Volume 15: Issue 2, 1999.
REFERENCE: Zava, DT, et al. 1998. Estrogen and progestin bioactivity of foods, herbs, and spices. Proceedings of the Society for Experimental Biology and Medicine 217(3):36.
