DOES IT WORK?BACKGROUND: Chaste tree got its name from the way medieval monks were said to chew on its leaves to help them maintain their celibacy. Herbalists, however, recommended it for women, believing its berries could help to normalise the menstrual cycle.
Doctors in ancient Greece wrote that it was beneficial for diseases of the uterus. Its use had faded until the 1970s when it drew renewed attention under its scientific name, Vitex agnus-castus. It became the herb of choice for menstrual problems until black cohosh and other herbs surfaced. However, interest in chaste tree berries remains high for menopausal symptoms.
EVIDENCE FROM STUDIES
The onset and development of menopause can lead to a variety of symptoms. The changes in different hormone levels during menopause are still not fully understood. This is further complicated by the irregular menstrual cycles that characterise this transition. On top of this, research studies have been inconsistent in their definitions and descriptions of the symptoms that participating women have reported.
This is particularly relevant to chaste tree extracts as their effectiveness appears to vary with the stage of menopause. There is better evidence to support the use of chaste tree for the earlier premenstrual syndrome (PMS) than for later menopausal symptoms. The symptoms themselves are often similar (hot flushes, mood swings, vaginal dryness), with menstrual irregularities being limited to earlier stages. The intensity of the symptoms tends to be greater in the earlier stages.
Chemical analyses of chaste tree extracts have identified numerous substances which act on many biochemical systems. PMS and menopausal symptoms are likewise connected to changes in many different biochemical pathways. In spite of the results of such tests, controlled studies have seldom been conducted on chaste tree extracts.
Two of the first studies on menopausal women were published in 2001 and 2003. Both found beneficial results from taking chaste tree extracts, but control groups were not used and the studies had several other limitations. A small number of randomised controlled trials have been conducted with menopausal women using multi-herb components.
The results were inconsistent in addition to making it impossible to determine which herbs might have been beneficial.
The largest study compared a German product containing extracts of chaste tree and seven other herbs with other herbal remedies and a placebo. It found no differences between any of the groups except at one time-point when the placebo group did best. However, this study has been critiqued for enrolling only women with mild symptoms which would have made it more difficult to detect improvements.
A small number of controlled studies have shown that chaste tree extracts may alleviate PMS symptoms.
PROBLEMATIC ASPECTS
Adverse effects have not been reported in clinical studies. Some people experience headaches and gastrointestinal problems when taking chaste tree extracts, but the symptoms are relatively mild and reversible. Concerns have been raised about the use of chaste tree during pregnancy, but the issue has not been adequately investigated.
RECOMMENDATIONS
Chaste tree has demonstrated some beneficial effects with PMS, though the results have not been consistent. Given concerns about hormone replacement therapy, chaste tree may provide a helpful alternative.
However, it will be important to examine the safety of using chaste tree for extended periods before its long-term use can be recommended.
Dónal O’Mathúna has a PhD in pharmacy, researching herbal remedies, and an MA in bioethics, and is a senior lecturer in the School of Nursing, Dublin City University. He is author of Alternative Medicine: The Christian Handbook, Updated and Expanded Edition, Zondervan, 2007
