Chaste tree extract is an herbal remedy obtained from Vitex agnus-castus, an aromatic, flowering member of the mint family. Its common name is derived from Greek mythology and customs that associate the shrub with promoting chastity. The Vestal Virgins of ancient Rome also believed the plant inspired venereal discipline, and carried its branches as a symbol of purity. Later, Christian monks took the symbolism a step further by preparing a tonic from the leaves and berries to help allay sexual desires, which earned the plant the additional nickname of monk’s pepper.
For thousands of years, chaste tree, sometimes referred to as simply vitex, has been regarded as an important phytomedicine to treat gynecological disorders. The Greek physician Hippocrates, also known as the Father of Medicine, recommended the use of the plant for menstrual disorders when he wrote, “let the woman drink dark wine in which the leaves of the chaste tree have been steeped.” Today, European physicians advocate the use of chaste tree extract to treat a variety of female complaints. In fact, the German Commission E lists menopause, irregular menstrual cycle, mastodynia, and premenstrual syndrome (PMS) among its potential applications. It is also commonly used to enhance fertility and to stimulate the production of breast milk.
The pharmacological effects of chaste tree extract are due to the presence of several chemicals, including various iridoid glycosides, diterpenoids, monoterpenoids, progestins, and the flavonoids casticin, quercetagetin, and kaempferol. Researchers believe that the hormone-balancing effects of the plant are due to these compounds stimulating the pituitary gland and competing at progesterone-dependent receptor sites. The latter is significant since a deficiency in progesterone is often to blame for infertility in women.
The extract also appears to exert some effects on men. As with women, chaste tree extract stimulates the production of gonaditropins by the pituitary gland, which in men triggers the release of sex hormones from the testes. One study indicates that chaste berry inhibits prolactin at higher dosages, which has the subsequent effect of lowering testosterone levels. While most men may not consider this advantageous, it may be useful to those battling prostate cancer since dihydrotestosterone, a by-product of testosterone, contributes to accelerated cell growth.
Studies have shown that chaste berry extract is safe in therapeutic dosages. However, since the herb yields estrogenic activity, those undergoing treatment for a hormone-driven cancer should avoid it. Likewise, it should not be taken during pregnancy or while taking hormonal drugs, including oral contraceptives. Chaste berry also affects dopamine receptor sites, so it should not be combined with dopamine D2-antagonists, such as chlorpromazine. While side effects are relatively rare, headache, stomach upset, and allergic reactions have been reported.