Modern Use

Scientific research on black cohosh began with investigations of its chemistry in the early twentieth century. Clear attribution of biological activity to a single chemical component remains illusive. It is believed at least three different chemical fractions soluble in alcoholic extracts may contribute to positive benefits in the treatment of menopausal symptoms.

By the mid 1950s sufficient scientific evidence, coupled with extensive clinical experience, made black cohosh preparations widely accepted and prescribed by German gynecologists, primarily as a an alterative to hormone treatment in menopausal disorders. By that time, hormonal replacement therapies were already recording unwanted side effects in a large number of patients. By 1962 at least 14 clinical studies (though not controlled clinical studies in the modern sense) had been published on the use of black cohosh products in over 1500 patients. These studies, some over 50 years old, began to establish clear scientific evidence for the safety and effectiveness of black cohosh in the treatment of premenopausal and menopausal symptoms including a reduction in the severity and duration of hot flashes along with an improvement of depressive moods.

Clinical studies

Today in Germany, black cohosh preparations are used in the treatment of menopause to improve symptoms such as hot flashes, depression and sleep disturbance. In 1985, German researchers found that black cohosh produced an effect on serum concentrations of pituitary hormone levels, including a significant and selective reduction of luteinizing hormone (while not significantly effecting levels of prolactin and follicle stimulating hormone). Hot flashes have been linked to a significant spike in the release of luteinizing hormone. The study provided a way to measure the endocrinological, particularly estrogenic effects, of black cohosh. A follow-up study failed to identify a single chemical component responsible for the luteinizing hormone suppressing activity, leading researchers to believe that synergistic effects of several chemical fractions were involved in the biological activity, competing with estradiol for binding sites on receptor proteins.

Recent clinical studies have shed further light on the herb's effects. A 1982 an open multi-center German clinical study involving data on 629 patients from 131 general practitioners and gynecologists was published. The researchers found that after six to eight weeks of treatment, 80 percent of patients had beneficial effects. In over 49 percent of volunteers there was dramatic relief in reduction of hot flashes, sweating, headache, vertigo, palpitation and tinnitus, while over 39 percent reported significant reductions of these symptoms, along with a lessening of nervousness, irritability and depression. Side effects (unspecified gastrointestinal problems) were reported for seven percent of the women. None of the side effects were serious enough to discontinue treatment.

A 1987 German double blind study compared estrogen replacement therapy with black cohosh for three months in eighty women. Thirty received a black cohosh extract (8 mg per day), 30 received black cohosh, and 20 volunteers received placebo. The black cohosh preparation was well-tolerated and produced significant improvement in the test parameters, which included menopausal symptoms as measured by the Kupperman Menopausal Index, depressive symptoms as measured by the Hamilton Anxiety Scale, as well as its effect on vaginal epithelium cells. The author concluded that black cohosh not only produced safe and efficacious results, but compared to estrogen replacement therapy, is suitable as a treatment of choice in menopausal symptoms.

A 1988 German clinical study compared treatment with three different estrogen therapies and an extract of black cohosh in 53 women (under 40 years of age). Many had experience surgical removal of an ovary leading to development of menopausal-like symptoms. Treatment with the black cohosh extract was found to be comparable to treatment with the three conventional drug preparations tested. The authors concluded that in cases where conventional hormone therapy is contraindicated, the plant extract is the therapy of choice.

In 1991 another German research group conducted a study involving 110 menopausal women. They demonstrated for the first time in a clinical trial that the extract selectively suppresses luteinizing hormone secretion in menopausal women, and further confirms an estrogenic effect of the alcoholic fractions of black cohosh root.