Vitex (Vitex agnus-castus) is an Asian and Mediterranean deciduous shrub also known as the chaste tree, chasteberry, monk’s pepper tree, Abraham's balm and wild pepper. Vitex grows to between six and seven meter tall and medicinally the peppercorn-like berries of the tree are useful in the treatment of female reproductive disorders. However, some reports also suggest that the small lilac flowers also possess similar medicinal properties to the berries. Traditionally the vitex was considered able to lower the libido, hence its name the chaste tree and hence why it was drunk by monks in high amounts. Historical records show that it has been used for this purpose at least since Roman times. More recently the use of vitex have been confined to the treatment of female reproductive health issues. In particular, vitex may relieve some of the unpleasant effects of menses and the menopause because of its balancing effects on hormonal regulation. It is also used as a galactogogue to increase milk production in lactating mothers.
The active constituents of vitex include the flavonoids isovitexin, orientin, casteican and chrysophanol D; iridoids such as aucubin, a p-hydroxybenzyl derivative of aucubin called agnuside, and eurostile; volatile oil which is composed of mono- and sesquiterpenes including cineol, pinene and limonene; the essential fatty acid linoleic acid, carotenoids; and vitamin C. Animal experiments using rats suggest that extracts of vitex are able to lower prolactin levels and in this way affect hormonal regulation. However, it is unknown which component of the plant is able to cause this biochemical effects. Mechanistically, vitex may reduce prolactin levels through a direct stimulatory effect on the dopamine receptor. In addition vitex may increase progesterone levels at the expense of oestrogen though an inhibitory effect on follicle stimulating hormone and a stimulatory effect on luteinising hormone. As well as its effects on female reproductive function, vitex may also have antioxidant effects in humans.