Ready for a pop quiz? How did chaste tree get its name? If you’re thinking that maybe it has something to do with chastity, you’re right (or you cheated and read the next sentence). During medieval times, chaste tree (Vitex agnus-castus) was said to suppress the libido, so was often suggested for this purpose. Modern research conducted on chaste tree has not noted any libido-suppressing effects. Studies have, however, shown that this herb is singularly valuable for treating disorders of the menstrual cycle.

Pharmacology

It has been clinically established that chaste tree increases luteinizing hormone (LH, a hormone necessary for proper reproductive function) and progesterone production through its activity on the neurotransmitter dopamine. Chaste tree, or vitex, also decreases elevated prolactin levels, which can suppress levels of other sexual hormones. This helps re-establish a normal balance of estrogen and progest-erone during the menstrual cycle.

Clinical Research

Hormone balance is important because some women suffer from premenstrual syndrome (PMS) and other menstrual irregularities due to underproduction of the hormone progesterone during the second half of their cycle. Studies show that using chaste tree once daily over several months helps normalize hormonal balance and alleviate symptoms of PMS such as bloating, cravings, fatigue, and mood swings.

Both standardized chaste tree extract and 200 mg vitamin B6 were effective in a double-blind study of women with PMS, with the first group taking these supplements showing more subjective overall improvement. In another placebo-controlled clinical study, women with PMS were given chaste tree or a placebo. By the end of the study, women taking the herb had a significantly greater reduction in overall PMS symptoms (including irritability, headache, and breast tenderness) than the placebo group. Another recent, multicenter trial on the efficacy of a chaste tree extract investigated 50 patients with PMS. Researchers determined that the extract helped ease PMS, mainly reducing symptoms rather than the length of the syndrome.

Chaste tree may also be as effective as the drug fluoxetine (Prozac) in relieving symptoms of a severe form of PMS called premenstrual dysphoric disorder. This herb was particularly useful in relieving physical symptoms.

Vitex has other benefits for the female reproductive system. Women with heavy menstrual flow have elevated levels of the hormone prolactin. As chaste tree helps balance elevated prolactin, it may be valuable in cases of menorrhagia. It has certainly been found helpful in other menstrual-related situations, such as breast pain and scanty/irregular periods.

Dosage and Cautions

The berry-like fruit of chaste tree is what’s used therapeutically. Although no specific chemicals have been identified as the “active” components, a number of natural compounds are present, including essential oils, flavonoids (including casticin), and iridoid glycosides (agnoside). With a standardized extract, as little as 20 mg up to 120 mg every morning may be effective. Chaste tree, however, is not a fast-acting herb. It may need to be used continuously for at least three menstrual cycles (and up to 18 months) before results are forthcoming.

Chaste tree is not recommended for use during pregnancy. If you take oral contraceptives, consult a qualified healthcare professional prior to using chaste tree.