Overview
Chasteberry is frequently called by its Latin name vitex or, alternatively, agnus-castus. A shrub in the Verbena family, chasteberry is commonly found on riverbanks and nearby foothills in central Asia and around the Mediterranean Sea. After its violet flowers have bloomed, a dark brown, peppercorn-size fruit with a pleasant odor reminiscent of peppermint develops. This fruit is used medicinally.
As the name implies, for centuries chasteberry was thought to counter sexual
desire. A drink prepared from the plant’s seeds was used by the Romans to diminish
libido, and in ancient Greece, young women celebrating the festival of
Demeter wore chasteberry blossoms to show that they were
remaining chaste in honor of the goddess. Monks in the Middle Ages used the fruit
for similar purposes, yielding the common name “monk’s pepper.”
Therapeutic Dosages
The typical dose of dry chasteberry extract is 20 milligrams taken one to three times daily. Chasteberry is also sold as a liquid extract to be taken at a dosage of 40 drops each morning. However, extracts that require lower or higher dosing are also available.
Therapeutic Uses
The modern use of chasteberry dates to the 1950s, when the German
pharmaceutical firm Madaus first produced a standardized extract. This herb has
become a standard European treatment for cyclic breast tenderness, a condition
related to premenstrual syndrome (PMS) that is sometimes called cyclic
mastitis, cyclic mastalgia, mastodynia, or fibrocystic breast disease. Chasteberry
also appears to be useful for general PMS symptoms.
Chasteberry is believed to work by suppressing the release of prolactin
from the pituitary gland. Prolactin is a hormone that naturally rises
during pregnancy to stimulate milk production. Inappropriately increased
production of prolactin may be a factor in cyclic breast tenderness, as well as
other symptoms of PMS.
Elevated prolactin levels can also cause a woman’s period to become irregular
and even stop. For this reason, chasteberry is sometimes tried when menstruation
is irregular or stops altogether (amenorrhea). Persons should not attempt
to self-treat significant menstrual irregularities without a full medical
evaluation. Serious medical conditions could result.
High prolactin levels can also cause infertility in women. For this reason, chasteberry is sometimes tried as a fertility drug; however, the two double-blind studies performed to evaluate this possible use failed to return statistically significant results. Finally, chasteberry is sometimes used for menopausal symptoms, but there is as yet no evidence that it is effective, either alone or in combination with other herbs.
Scientific Evidence
There is a growing body of scientific research supporting the use of chasteberry.
Cyclic mastalgia. A double-blind, placebo-controlled trial of ninety-seven women with symptoms of cyclic mastalgia found that treatment with chasteberry extract significantly reduced pain intensity by the end of one menstrual cycle. The reduction continued to increase throughout the second menstrual cycle, and at the end of both the first and the second cycle, women in the treated group were doing better than those receiving a placebo.
However, in the third cycle, the benefits of chasteberry treatment reached a plateau, while the placebo group continued to improve. At the end of the third cycle, those receiving chasteberry were still doing better, but the difference was no longer statistically significant.
Another double-blind trial of 104 women compared a placebo against two forms of chasteberry (liquid and tablet) for at least three menstrual cycles. The results showed statistically significant and comparable improvements in the treated groups, compared with a placebo.
Benefits were also seen in a double-blind trial that enrolled 160 women with cyclic breast pain. The women were given either chasteberry, a drug related to progesterone, or a placebo, and were followed for at least four menstrual cycles. Although there were many dropouts, the results again suggest that chasteberry is superior to a placebo.
Premenstrual syndrome (PMS). A double-blind, placebo-controlled study of 178 women found that treatment with chasteberry over three menstrual cycles significantly reduced general PMS symptoms. The dose used was one tablet three times daily of a dry chasteberry extract. Women in the treatment group experienced significant improvements in symptoms, including irritability, depression, headache, and breast tenderness. In a similar study, 217 women with moderate to severe PMS were randomized to receive chasteberry extract or placebo. After three menstrual cycles, the women in the treatment group reported fewer symptoms. A smaller trial involving 67 women also reported on the effectiveness of chasteberry for PMS. Chasteberry in combination with St. John’s wort was also studied for PMS symptoms during late menopause with favorable results in at least one small trial.
There is also some conflicting evidence, though. A double-blind trial compared chasteberry to vitamin B6 (pyridoxine) instead of a placebo. The two treatments proved equally effective. However, because vitamin B6 itself has not been shown effective for PMS, these results mean little.
Two other studies are often cited in support of chasteberry as a treatment for PMS. These were rather informal reports of a total of about three thousand women with PMS given chasteberry by their physicians. The physicians rated chasteberry as effective about 90 percent of the time, but in the absence of a control group, these reports are not very meaningful.
Irregular menstruation. One double-blind trial followed fifty-two women with a form of irregular menstruation known as luteal phase defect. This condition is believed to be related to excessive prolactin release. After three months, the women who took chasteberry showed significant improvements.
Safety Issues
There have not been any detailed studies of the safety of chasteberry. However, its widespread use in Germany has not led to any reports of significant adverse effects, other than a single case of excessive ovarian stimulation possibly caused by chasteberry.
Because it lowers prolactin levels, chasteberry is not an appropriate treatment for pregnant or nursing women. Safety in young children or those with severe liver or kidney disease has not been established.
There are no known drug interactions associated with chasteberry. However, it is quite conceivable that the herb could interfere with hormones or medications that affect the pituitary gland. Chasteberry may interfere with the action of hormones or drugs that affect the pituitary.
Bibliography
Halaska, M., et al. “Treatment of Cyclical Mastalgia with a Solution Containing a Vitex agnus castus Extract.” Breast 8 (1999): 175-181.
He, Z., et al. “Treatment for Premenstrual Syndrome with Vitex agnus castus: A Prospective, Randomized, Multi-center Placebo Controlled Study in China. Maturitas 63, no. 1 (2009): 99-103.
Ma, L., et al. “Evaluating Therapeutic Effect in Symptoms of Moderate-to-Severe Premenstrual Syndrome with Vitex agnus castus (BNO 1095) in Chinese Women.” Australian and New Zealand Journal of Obstetrics and Gynaecology 50, no. 2 (2010): 189-193.
Schellenberg, R. “Treatment for the Premenstrual Syndrome with Agnus castus Fruit Extract.” British Medical Journal 322 (2001): 134-137.
Van Die, M. D., et al. “Effects of a Combination of Hypericum perforatum and Vitex agnus-castus on PMS-like Symptoms in Late-Perimenopausal Women: Findings from a Subpopulation Analysis.” Journal of Alternative and Complementary Medicine 15, no. 9 (2009): 1045-1048.
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