Black cohosh (Cimicifuga racemosa), of the family Ranunculaceae, is a hardy perennial indigenous to the eastern U.S. but widely cultivated as an attractive garden ornamental. The plant can grow to a height of 8 feet. It has large, irregular, tooth-edged leaves and a flower stalk supporting tall plumes of fragrant white flowers, which bloom from June through September. It prefers rich sandy soil, and is most often found growing in woodland habitats. The name “cohosh“ is derived from an Algonquian word meaning “rough,“ which describes the knotty texture of the rhizome. The rhizomes are dark brownish-black in color, hence the name black cohosh. The roots and rhizome — which have a bitter, acrid taste — are the medicinally useful part of the plant. The Latin name Cimicifuga means “bug-repellent,“ reflecting one of its popular uses. There are 15 species comprising the genus Cimicifuga, and various species in Europe are referred to by the common name “bugbane“ for its purported insect-repelling activity.
Black cohosh’s name is derived from a description of the rhizomes, which, along with the roots, are the medicinally useful part of the plant.
Chemical Composition and Active Constituents
The rhizomes and roots contain triterpene glycosides actein, cimicifugoside, and 27-deoxyactein, which are considered the main active constituents. Eight newly described glycosides have recently been isolated and characterized from the Japanese species Cimicifuga simplex. Other constituents include the alkaloid n-methylcytisine along with many other related quinolizidine alkaloids, the isoflavone formononetin, and the phenolic acids isoferulic and salicylic acids, as well as various tannins.
Black Cohosh: Medicinal Uses and Pharmacology
Native Americans used the roots and rhizomes for a variety of ailments, including menstrual cramps and pain associated with labor and delivery. Eclectic physicians in the U.S. during the 1800s used black cohosh to treat uterine difficulties, stimulate menstrual flow, and reduce discomforts during labor. It was one of the main ingredients in Lydia Pinkham’s Vegetable Compound, which was one of the most popular patent remedies for “women’s complaints“ during this period. Black cohosh has been used in Germany since the mid-1950s for treatment of menopausal symptoms.
The strongest evidence for a clinical benefit of black cohosh is in the treatment of postmenopausal symptoms. Eight clinical trials have been published since the early 1980s; most of the studies have been carried out in Germany. The German Commission E approves black cohosh for “premenstrual discomfort, dysmenorrhea, or menopausal neurovegetative ailments.“ One of the first studies involved 36 postmenopausal women treated with Remifemin (an alcoholic extract of black cohosh roots). Remifemin is a brand-name product (manufactured by Schaper and Brummer in German) and is standardized to contain triterpene glycoside, usually 1 mg of 27–deoxyacteine per tablet. Treatment for 12 weeks resulted in a decrease in menopausal symptoms, with no reported side effects. These results were supported by a similar study published the next year. This 12-week study of 50 postmenopausal women assessed symptoms utilizing the Profile of Mood States (POMS) and Clinical Global Impression Scale (CGI). Remifemin treatment resulted in a significant improvement in both the POMS and CGI scales. The only side effect noted was mild gastrointestinal disturbances in four patients.
Several studies have compared Remifemin to conventional treatment of menopausal symptoms with various forms of estrogen or diazepam (Valium). One study compared the efficacy of Remifemin in treating menopausal symptoms to hormone treatment or therapy with a psychotropic drug in 60 patients. Remifemin (two 1 mg tablets twice daily), conjugated estrogens (Premarin, 0.625 mg/day) or diazepam (Valium, 2 mg/day) was given for three months. Remifemin was found to be more effective than Premarin or Valium in relieving the depressive mood and anxiety associated with menopause. These results were further supported in a study involving 80 patients who were treated for 12 weeks with either Remifemin (8 mg daily), conjugated estrogens (0.625 mg daily) or placebo. Remifemin was more effective in reducing anxiety, atrophic vaginitis, and the frequency of hot flashes. In another clinical trial, 60 women who had hysterectomies with at least one remaining ovary were given either estriol (1 mg daily), conjugated estrogens (1.25 mg daily), estrogen-gestagen (Trisequens, 1 tablet daily), or Remifemin (8 mg daily). Menopausal symptoms, such as hot flashes and nervousness, were significantly reduced by all treatments, with no differences noted between the various therapies. Remifemin’s ability to improve menopausal symptoms was compared to previous therapy with estrogen replacement or psychoactive drugs in 629 female patients. Remifemin treatment for 6? weeks improved menopausal symptoms in more than 80% of women. The only side effect reported was mild GI distress in 7% of the patients. One study examined the effectiveness of Remifemin in 50 women who had discontinued estrogen replacement therapy. Remifemin was administered for 6 months. Effectiveness was evaluated by a gynecologist as very good in 21 patients and good in 20 patients, with little effect seen in 9 patients.
A double-blind trial in 110 postmenopausal women, in which half were treated with Remifemin (8 mg daily) for 8 weeks, resulted in significant improvements in menopausal symptoms for those receiving Remifemin. Blood levels of luteinizing hormone (LH), but not follicle stimulating hormone (FSH), were significantly reduced in the treatment group. Many of the symptoms of menopause are believed to result from elevated blood levels of LH.
Animal and In Vitro Studies
The effects of an orally administered ethanolic extract of black cohosh rhizomes on uterine growth in immature mice and on vaginal cornification in ovariectomized rats were investigated. Results revealed no signs of estrogenic growth of uterine or vaginal tissues. This study suggests that the beneficial effects of black cohosh are not due to a classic estrogen trophic effect in these tissues.
In another study, lipophilic extracts of black cohosh roots were subjected to gel-exclusion chromatography, with various fractions tested for their ability to reduce LH secretion in ovariectomized rats and to compete with 17-b-estradiol binding sites in uterine tissue. Several fractions had LH-reducing activity, whereas others were able to compete for the estrogen receptor. The results of this study suggest the presence of multiple constituents in black cohosh roots that could act synergistically to bring about a coordinated pharmacological response.
The above study supports an earlier investigation of chromatographically separated fractions from methanol extracts of black cohosh rhizomes. At least three fractions were found that could either decrease LH blood levels in ovarectomized rats or compete with estrogen in an in vitro estrogen receptor assay. One of the isolated fractions was further characterized and found to include the isoflavon formononetine. Isolated formononetine was shown to be a competitor for estrogen in the receptor assay, but failed to decrease LH levels in ovariectomized rats. Extracts from two Cimicifuga species (Cimicifuga heracleifolia and Cimicifuga dahoric) have been used extensively as antipyretic, analgesic, and anti-inflammatory agents in Japanese oriental medicine. Ferulic acid (FA) and isoferulic acid (IFA) were found to be active anti-inflammatory compounds in methanol extracts of the roots of these species. These compounds were found to inhibit interleukin production in response to influenza virus infections in vitro and in vivo. The in vitro studies were done in a murine macrophage cell line infected with influenza virus. The in vivo study involved injecting mice with the influenza virus with and without prior oral administration (5 mg/mouse/day) of Cimicifuga extracts,0.5 mg/mouse/day of FA, or 0.125 mg/mouse/day of IFA. The three treatments reduced IL-8 levels in bronchoalveolar lavage obtained two days after infection. These results indicate that at least two components in Cimicifuga may be responsible for the extract’s analgesic and anti-inflammatory activity.
Limited data is available for additional effects of black cohosh root extracts. The steroidal triterpene derivative actein was shown to lower blood pressure in rabbits and cats, but not dogs. This hypotensive effect has not been demonstrated in humans. Root extracts from Cimicifuga foetida and Cimicifuga heraclefolia species were recently shown to inhibit parathyroid hormone-induced bone reabsorption in tissue culture and in ovariectomized rats. Isopropanolic extracts of Cimicifuga racemosa were shown to inhibit the proliferation of estrogen-dependent breast cancer cell lines in a dose-dependent manner.
Black Cohosh: Side Effects and Toxicity
The FDA lists black cohosh as an herb of “undefined safety.“ The German Commission E notes no contraindication, with occasional gastric upsets likely due to the high tannin content. Because of the lack of long-term toxicity studies, its use is recommended for no more than six months. Black cohosh is contraindicated in pregnancy, and large doses could result in miscarriage. Black cohosh has not been shown to be carcinogenic or mutagenic. Toxicity studies in rats revealed no toxicological changes when the herb was given at high doses for six months. No reports of adverse effects on lactation or in nursing children have been made. No drug interactions have been noted. Remifemin has often been used in conjunction with estrogen replacement therapy, with no reported adverse effects.
Dosage Forms and Recommendations
All clinical studies (mostly Germany-based) have utilized the alcoholic extract of Cimicifuga racemosa Remifemin. Nearly 10 million one-month supplies of Remifemin were sold in Australia, Germany, and the United States in 1996. Clinical trial results indicate that dosages of 4? mg per day were effective in reducing many of the symptoms of menopause.Black Cohosh – Uses, Dosage, Health Benefits and Side Effects