My friends love the fact that I write articles for #HBS. When we meet for lunch, they unashamedly ask me about the latest topic and want the inside track on evidence-based science versus urban myth versus blogger fiction.
The odd thing is that they rarely (if ever) ask me to talk about regular medical stuff. Yesterday, the topic over lunch was vitex agnus castus or chasteberry.
As we waited for our meal to arrive, I gave a brief introduction to the "agnus castus paradox." Vitex agnus castus is associated with female reproductive health including the promotion of female fertility but it is also an anaphrodisiac (an anti-aphrodisiac). How strange that nature would program a berry to both promote and suppress procreation?
Lunch arrived and we moved onto other topics. Over coffee, my friends asked me to explain some more about the 'paradox'. These cunning women had an agenda. One of my friends is trying to conceive and would travel to the moon and eat moondust if that would help her.
Another one of my friends has a young toddler and, let's say, was interested in the anaphrodisiac effect for her husband (for now at least).
What is Vitex?
The chaste tree is a small shrub that grows well near rivers and foothills in the Mediterranean region and in Asia. The tree produces pretty, violet-colored flowers. Once the flowers have bloomed, the tree produces small (about the size of a peppercorn) brown fruit that smells somewhat like mint - the chaste berry. The aromatic brightly colored plant attracts pollinating bees and hummingbirds.
The chaste berry is also known as Vitex agnus castus in Latin. Agnus castus is Latin for "chaste lamb" as the berries are believed to reduce sexual desire. For the same reason, it is sometimes called "monks pepper." We will deal with that piece of propaganda later.
In women, chasteberry is used for reproductive health.
Hence the paradox.
The medicinal use of chasteberry dates right back to the Greek physician, Dioscorides, who used it over 2000 years ago.
The berries contain essential oils (e.g., limonene, sabinene, 1,8-cineole [eucalyptol]), iridoid glycosides (e.g., agnoside, aucubin), diterpines (e.g., vitexilactone, rotundifuran), and flavonoids (e.g., apigenin, castican, orientin, isovitexin (1).
There are 100 chasteberry products for sale on Amazon. It is available as tea, liquid extract, capsules, tablets, and an essential oil. Chasteberry is relatively inexpensive - a 400mg tablet costs just 4 cents.
Is There any Research?
There are just 181 publications related to chasteberry which includes only 22 clinical trials. Let's compare this to the overall research database for 'fertility' which has over 100,000 publications and 3000 clinical trials. Agnus castus is not a majority shareholder here.
Does Vitex Help Treat Endometriosis?
Endometriosis is a painful condition where uterine tissue is found outside the uterus. Not only is it painful, but it is also associated with infertility. Despite the fact that agnus castus is positioned as a woman's best friend, there is nothing in the medical literature to suggest that vitex helps endometriosis. Therefore, if vitex helps with fertility, we cannot say that the mechanism is via helping endometriosis.
There is no proof that vitex helps endometriosis.
Does Vitex Reduce Uterine Fibroids?
Again, fibroids are overgrowths of the muscle of the uterus and are one of the causes of infertility. Again, there is no science to suggest that vitex helps with uterine fibroids.
There is no proof that vitex helps with fibroids.
Does Vitex Clears Up Acne?
No. There is a study showing that Vitex negundo (not castus) inhibited the activity of a bacteria that causes acne in a laboratory model (2). This is neither relevant nor convincing.
There is no evidence that vitex clears up acne.
Does Vitex Help Treat Amenorrhea?
A systematic review was published this year which looked at herbal remedies for oligomenorrhea and amenorrhea (3).
Amenorrhea means no menstrual cycles while oilgomenorrhea means long menstrual cycles. Iranian researchers identified 198 medicinal plants used in the treatment of menstrual disorders. The review identified vitex as one of the plants used in the management of menstrual disorders but did not provide any in-depth information on the effectiveness of vitex in this population.
Australian investigators did a systematic review of herbal medicines for menstrual irregularities associated with polycystic ovarian syndrome (4). They found 33 relevant studies in 762 women.
They found that six herbal medicines (Vitex agnus-castus, Cimicifuga racemosa, Tribulus terrestris, Glycyrrhiza spp., Paeonia lactiflora, and Cinnamomum cassia) 'may have beneficial effects for women with oligo/amenorrhea and polycystic ovarian disease'.
It seems that the available systematic reviews are not that helpful here. Let's look at source data. It seems that the only clinical trial that we can look at is a study involving a homeopathic formulation of vitex and not the parent compound itself.
German investigators looked at an agnus castus homeopathic remedy in 37 women with oligomenorrhea and 30 women with amenorrhea (5). The women either received a homeopathic remedy containing agnus castus or placebo.
No statistically significant effect on spontaneous menstruation or take home baby rate was noted. Interestingly, side effects were noted in both arms of the study.
There is no human clinical trial data to support a role for vitex in amenorrhea or oligomenorrhea.
Does Vitex Relieve PMS Symptoms?
A full Cochrane review of the effects of agnus castus in premenstrual syndrome was published from a group of researchers from the UK earlier this year. Considering the fact that this was a Cochrane review and that it was published this year, would make this the final word on the subject.
Problem is that the investigators withdrew the review which makes us none the wiser on the subject (6).
German investigators carried out a randomized, double-blind, placebo-controlled study over three menstrual cycles to evaluate the effect of agnus castus on premenstrual syndrome.
The study found statistically significant improvements in symptoms of irritability, mood alteration, anger, headache, breast fullness and bloating in the agnus castus arm of the study as compared to the placebo arm. (7).
Agnus castus was well tolerated in this study.
A follow-up study from the same research group in Germany looked at three different doses of vitex agnus castus (8, 20 and 30 mg) in on pre-menstrual symptoms in 162 women over three menstrual cycles (8).
Premenstrual symptoms were assessed by patients using visual analog scales for the symptoms irritability, mood alteration, anger, headache, bloating and breast fullness.
Improvements in the pre-menstrual score were not significantly better, between 30mg and 20mg, but were statistically significantly better between 20mg and 8mg. The bottom line here is that the sweetspot for vitex agnus castus in this study was 20 mg and this study again confirms the efficacy of agnus castus for premenstrual symptoms.
Vitex has been shown to help with pre-menstrual symptoms.
Does Vitex Promote Lactation?
A 2008 Canadian review looked at the safety and efficacy of vitex agnus during pregnancy and lactation (10). The reviewers searched 7 electronic databases and found poor evidence based on theoretical and expert opinion and in vitro studies that chastetree may have estrogenic and progesteronic activity, uterine stimulant activity, emmenagogue activity and prevent miscarriages in pregnancy.
I don't think you would want to use an agent that can cause uterine contractions to prevent miscarriages. The conclusions on lactation were based on expert opinion and the 'theoretical and expert opinion conflict as to whether chastetree increases or decreases lactation'.
There is no scientific evidence to support a role for agnus castus in lactation. Experts don't agree on agnus castus in lactation so I think we will err on the side of safety and vote no for this one.
Does Vitex Lowers Menopause Symptoms?
A 2012 systematic review from Germany evaluated available data on vitex in the menopause (11). The search included keywords such as "vasomotor symptoms, hot flashes, vaginal atrophy, psychological problems, endometrium, sleep, concentration, cognition in combination with vitamins, multivitamins, minerals, multiminerals."
All data was reviewed by 4 independent reviewers which minimizes the risk of bias or error. The comprehensive review failed to show any benefit of vitex on menopausal symptoms.
There is no science to support a role for vitex in the menopause.
Does Vitex Help Treat Enlarged Prostate?
Swiss investigators found that vitex extract caused prostate cell death and prevented prostate cell growth in a laboratory model (12).
The only evidence relating to vitex for prostate disease comes from a very preliminary laboratory cell model and as such we have to conclude that there is no evidence that vitex treats enlarged prostates.
Does Vitex Improve Female Fertility?
Experts in reproductive health from Stanford University School of Medicine studied the effect of a commercial blend of chasteberry, green tea, L-arginine, vitamins (including folate) and minerals on fertility in a double-blind, placebo-controlled study in women up to the age of 42 (9).
After three months, 14 of the 53 women in the intervention group were pregnant (26%) compared to four of the 40 women in the placebo group (10%).
This was statistically significant. It is hard to pin the take-home baby rate on the agnus castus as opposed to the other ingredients or the effect of the blend but something worked.
One human clinical trial showed that a blend of herbs, vitamins, and minerals which included agnus castus improved the fertility rate in a group of women.
Does Vitex Reduce Libido?
What an interesting question. There is no evidence that this is true. It is not just me who says so. A review paper published in 2005 agrees with me (13).
There is no proof that vitex reduces libido.
Is it safe?
A 2005 comprehensive review of the safety of vitex drew on data from 6 electronic databases, spontaneous reporting schemes of the WHO and national drug safety bodies, twelve manufacturers of agnus castus and five herbalist organizations (15). No language restrictions were imposed on this review. The conclusions of the study were as follows.
- Side effects of agnus castus were found to be mild and reversible.
- The most frequent adverse events were nausea, headache, gastrointestinal disturbances, menstrual disorders, acne, pruritus, and erythematous rash.
- No drug interactions were reported.
- Use of VAC should be avoided during pregnancy or lactation.
- Theoretically, VAC might also interfere with dopaminergic antagonists such as drugs used to treat schizophrenia.
There are two reasons for writing a negative "bottom line" in articles for #HBS:
- negative studies ie studies that show that something does not work and
- no studies ie there are no studies to comment on.
They are not one and the same thing. I am very conscious when writing these articles that absence of data does not mean that something does not work. It just means that there is no evidence to support that particular claim.
Based on science, what can we say about vitex?
We can say that vitex helps relieve pre-menstrual symptoms.
We can say that a combination blend of herbs, vitamins, and minerals may possibly help with fertility. That does not mean that agnus castus is the magic ingredient in this blend. It also needs to be said that there are many causes of infertility.
As we have seen, vitex does not help with some of the underlying causes of infertility eg endometriosis and fibroids. What we don't know is whether agnus castus helps with infertility and if so what specific types of infertility will respond to vitex?
Nature is pretty amazing and usually has a plan of some sort (even if we don't see it or appreciate it all the time).
It seems odd to me that nature would design agnus castus to promote fertility and also reduce libido as suggested by folklore. A paradox indeed. Could a paradox in nature be explained by human misinterpretation? Available science tells us that it is premature to talk about an "agnus catsus paradox."
We don't definitively know that agnus helps fertility.
We don't actually know that vitex is an anti-aphrodisiac as there are no studies.
Neither of my friends was thrilled with the inside scoop on vitex. I can see how people who are super busy trying to cope with the struggles of everyday life would prefer the folklore/bad blogger version if they appear to offer solutions.
That's just not the #HBS way.