Black cohosh is a traditional herbal medicine derived from the foot of a flowering plant, Cimicifuga racemosa. Also known as squaw root or black snakeroot it is classed as an adaptogenic herb as it helps women ‘adapt’ to changing hormone levels. Black cohosh is used to help balance female hormones and can relieve menopausal hot flushes and night sweats, relax menstrual cramps, boost a low libido and improve premenstrual syndrome (PMS). Black cohosh is especially helpful in reducing hormone-related mood swings, depression, anxiety and stress.
Black cohosh herb benefits
The dried roots of black cohosh contain a number of oestrogen-like plant hormones (phytoestrogens) of which formononetin is the most active. Rather than having an overt oestrogen-like action. However, Black cohosh also appears to improve hormone balance through a direct action on the brain. It has been shown to lower levels of LH produced by the pituitary gland by as much as 20%. This in turn decreases ovarian output of progesterone hormone to normalize oestrogen-progesterone balance. It may also reduce flushes by regulating blood vessel dilation.
Black cohosh for menopause
Black cohosh herb is one of the most widely studied alternatives to hormone replacement therapy (HRT). Research even shows that standardized extracts of Black cohosh are as effective in relieving hot flushes, vaginal dryness, depression and anxiety as standard HRT (conjugated oestrogens).
Data from twelve studies that used pharmaceutical quality Black cohosh supplements found they were 38.5% more effective than placebo in reducing menopausal symptoms.
In 48 women with menopausal sleep problems, those given Black cohosh showed significant improvements in sleep efficiency and decreased wake after sleep onset compared with placebo. Menopausal symptoms and quality of life quality also improved.
Studies which claim Black cohosh is not effective for menopause have used poor quality supplements that were not made to pharmaceutical standards (GMP). In the UK, Black Cohosh is now regulated as a traditional herbal medicine so that quality is assured.
A German trial has shown that Black cohosh plus St John’s Wort was effective in treating 78 per cent of women with hot flushes and other menopausal problems. Most women experience significant improvement in symptoms within two to four weeks. In another study, black cohosh out-performed diazepam and oestrogen HRT in relieving depressive moods and anxiety.
Black cohosh and endometriosis
The medical treatment of endometriosis often results in menopausal symptoms. A study involving 116 women with medically-induced menopause compared the treatment of hot flushes with Black cohosh or the prescribed hormone replacement therapy, tibolone. Both approaches were equally effective in treating hot flashes and sweating.
Black cohosh and libido
As Black cohosh has a normalizing effect on female sex hormones, it may be used to improve low sex drive where this is linked with hormonal imbalances, such as after childbirth, irregular menstruation and around the time of the menopause.
Black cohosh dose
A typical dose in the UK is 6.5 mg standardized extract, equivalent to 30mg – 55mg roots. Some products supply 540mg pure root extract.
Black cohosh side effects
High doses can cause headache, nausea or indigestion. A few cases of abnormal vaginal bleeding and miscarriage have been reported but it is not clear if black cohosh was responsible.
Black cohosh safety
Black cohosh should not be taken during pregnancy (may stimulate uterine contractions) or when breast-feeding.
Black cohosh does not have an oestrogen-like effect on the breast and appears to decrease local oestrogen formation in normal human breast tissue. There does not appear to be any association between Black cohosh and risk of breast cancer. It has even been used to treat hot flushes in women with tamoxifen-treated breast cancer but it is wise for women with a history of breast cancer to only use it under medical supervision.
Recent evidence suggests that Black cohosh may suppress oestrogen-sensitive endometrial cancer cells.
Rare cases of liver toxicity have been associated with Black cohosh. In most cases, other factors such as paracetamol use or high alcohol intake were involved and Black cohosh was not definitely identified as the cause. Five studies involving 1,117 women found no evidence that Black cohosh extract had any adverse effect on liver function.
It should however be used with caution in people with risk factors for liver disease and regular liver function tests may be advised in some cases.
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