|Monday, 04 December 2006 07:34|
0.1.1. What is black cohosh?
Black cohosh is an herb sold as a dietary supplement in the United States. It is known as both Actaea racemosa and Cimicifuga racemosa, a member of the buttercup family and perennial plant that is native to North America. Black cohosh was originally used by Native Americans in the treatment of many conditions, especially gynecologic disorders.1 Today, the roots and rhizomes are widely used in the treatment of menopausal symptoms and menstrual dysfunction.
What are common black cohosh preparations?
Commercially available preparations of black cohosh usually contain 1 mg of total standardized triterpene glycosides in each 20-mg dose of extract. The most widely used and best studied commercial formulation available in the United States is Remifemin®, which contains the proprietary black cohosh extract RemiSure™. Remifemin® has been used by women in Europe for 50 years with no adverse side affects. Numerous other brands of black cohosh are available, but most products on the market lack the standardization and research that can ensure efficacy and safety, and multi-ingredient compounds can potentially create problems from drug interactions.
What clinical studies have been done on black cohosh and its effect on menopausal symptoms?
Currently, the primary use of black cohosh extract is for alleviation of menopausal symptoms. The American College of Obstetrics and Gynecology guidelines on the use of botanicals for the management of menopausal symptoms support this use for up to six months, especially in treating the symptoms of sleep and mood disturbance, and hot flushes.2 At least eight studies of black cohosh therapy for menopausal symptoms, involving approximately 2,000 women, have been published.3 Almost all of these studies demonstrate efficacy in patients taking black cohosh extract similar to that of estrogen in the treatment of menopausal symptoms. Although some study results suggest that black cohosh may help relieve menopausal symptoms, other study results do not. Studies of black cohosh have yielded conflicting data, in part because of lack of rigor in study design and short study duration (6 months or less). In addition, interpretation of these studies is complicated by the fact that different amounts of black cohosh from different sources were used in the various studies and their outcome measures were different. However, the most consistent results for relief of menopause symptoms were obtained in studies utilizing standardized black cohosh extract, in particular Remifemin®. To provide more definitive evidence on the effects of black cohosh on menopausal symptoms, additional studies are being conducted.As with other herbal medicines believed to have potential estrogenic effects, there has been a concern about the safety of black cohosh in women with a personal history or strong family history of breast cancer. Although further research is needed, at least one tissue-culture study4 showed no stimulation of estrogen receptor positive breast cancer cell lines by black cohosh extract. This study found that black cohosh extract increased the inhibitory effect of tamoxifen (Nolvadex) on the breast cancer cell lines. In addition to tissue studies which have failed to document estrogen receptor stimulation, in 2004 a study of Remifemin®, which included women with a history of breast cancer (some of whom were taking tamoxifen), reported no significant adverse effects.5 Physicians should discuss the issue with their patients who are at risk for breast cancer and are considering taking black cohosh.
What are the interactions, adverse effects, and contraindications associated with black cohosh?
With the exception of a possible interaction with tamoxifen, there are no known interactions between black cohosh extract and any medications.6 In clinical studies,6 the only adverse effect reported with any significant frequency was mild gastrointestinal discomfort. In larger doses, black cohosh can cause dizziness, headaches, giddiness, nausea, and vomiting.7 Black cohosh is contraindicated during pregnancy because of its potential ability to stimulate uterine contraction.8 The safety of black cohosh in breastfeeding mothers and the degree of transmission of black cohosh in breast milk are unknown. Black cohosh usually has not been used for long periods, and published studies have followed women for only 6 months or less. Recently, a large study that followed postmenopausal women taking combined estrogen and progestin for an average of 5.2 years showed a small but significant increase in the risk of certain diseases, demonstrating the importance of long-term studies in revealing risks that may not be apparent in shorter studies.9 We recommend that, as with any dietary supplement, if you are taking any prescription drug or any other over-the-counter product, please check with your doctor or pharmacist first before using black cohosh. Your doctor or pharmacist is the best person to advise you based on your medical history and present state of health.
0.1.2. Is black cohosh FDA approved?
In the United States, black cohosh is sold as a dietary supplement, and dietary supplements are regulated as foods, not drugs. Manufacturers do not have to provide the Food and Drug Administration (FDA) with evidence that dietary supplements are effective or safe before marketing. Because dietary supplements are not always tested for manufacturing consistency, the composition may vary considerably from lot to lot.
|Last Updated on Friday, 28 October 2011 15:18|