Chaste tree is a large shrub (up to twenty-two feet tall) native to the Mediterranean and southern Europe. Although it flourishes on moist riverbanks, it is easily grown as an ornamental plant in American gardens, where its attractive blue-violet flowers are appreciated in midsummer.
The Greeks and Romans used this plant to encourage chastity and thought of it as capable of warding off evil.
Medieval monks were said to use the dried berries in their food to reduce sexual desire. As a result, it was also referred to as “monks’ pepper.”
Although Hippocrates used chaste tree for injuries and inflammation, several centuries later Avicenna, in Persian medicine, recommended it specifically for inflammation of the womb and also used it to encourage milk flow shortly after birth.
Current use of chasteberry is almost exclusively for disorders of the female reproductive system.
Oddly, the conditions for which it is most commonly recommended, premenstrual syndrome (PMS) and peri- or postmenopausal symptoms such as hot flashes, are associated with completely different hormone imbalances.
Two authors publishing the results of a survey of medical herbalists were led by this observation to suggest that chaste tree should be considered an adaptogen, possibly affecting the pituitary gland.
Usually the dried berries are the part of the plant used. In some Mediterranean countries, leaves and flowering tops are also harvested and dried for use.
It is perhaps surprising that chaste tree does not contain plant estrogens. Instead, progesterone, hydroxyprogesterone, testosterone, epitestosterone, and androstenedione have been identified in the leaves and flowers.
Animal research has shown that extracts of chaste tree berry have an effect on the pituitary gland of rats, reducing prolactin secretion. This has the impact of reducing milk production, exactly the opposite effect suggested by some of the ancient texts.
As a result of these studies, chaste tree has been suggested to treat conditions associated with excess prolactin. In a clinical trial of chasteberry for menstrual cycle abnormalities attributed to too much prolactin, the herb normalized both the cycle and the levels of prolactin and progesterone hormones.
It is also helpful for premenstrual breast tenderness, a condition linked to excess prolactin.
Several uncontrolled studies in Germany have shown that chaste tree extracts can reduce symp-toms associated with PMS. In one of these studies, the investigators reported higher blood levels of progesterone as a result of treatment.
As chaste tree can normalize hormone levels, it may be helpful for perimenopausal women with unusually short cycles or heavy bleeding.
In modern times, chaste tree is used primarily as a women’s herb for menstrual complaints. The flavonoids in chaste tree exert an effect similar to the hormone progesterone, although the plant contains no hormonal compounds. Chaste tree acts on the pituitary gland in the brain, normalizing the release of both follicle stimulating hormone (FSH) and luteinizing hormone (LH).
The overall effect is to regulate the menstrual cycle and slightly increase the production of progesterone in women who otherwise have irregular cycles. Many menstrual complaints are known to result from a relative lack of progesterone. When progesterone levels are low relative to estrogen, the result is often infertility, heavy bleeding, lack of periods, too-frequent periods, irregular periods, and premenstrual syndrome. Because it helps normalize LH levels, chaste tree alleviates these complaints. It can normalize and regulate menstrual cycles, reduce premenstrual fluid retention, and treat some cases of acne that flare up during menstruation.
Chaste tree’s berries also can be used for menopausal bleeding irregularities, such as frequent or heavy bleeding; it is often combined with hormonal herbs such as black cohosh or soy. Therapy of six months to one year is usually recommended.
Chaste tree is a slow-acting herb and can take months to produce effects. When treating infertility, chaste tree is continued for one to two years; it is discontinued if pregnancy occurs. Because the constituents in chaste tree — including flavonoids, iridoid glycosides, and terpenoids — gradually normalize FSH and LH levels, it helps allow for normal ovulation and pregnancy. Chaste tree also lowers the hormone prolactin, produced during stressful periods, which also may cause tender breasts and uterine cramps associated with PMS.