Menopause: a review of botanical dietary supplements

Since the release of the Women's Health Initiative (WHI) findings, an increasing number of dietary supplement products specifically targeting women in menopause have appeared in the American marketplace. This growth highlights the need for a critical evaluation of the tolerability and effectiveness of these products. The purpose of this article is to assess the evidence for safety and benefit of botanical monopreparations used for relief of menopause-related symptoms. The Cochrane Library and Medline databases were searched from January 1966 to October 2004, using a detailed list of terms related to botanicals and menopausal symptoms. Studies were considered eligible (1) if they were controlled trials of a botanical monopreparation administered orally for a minimum of 6 weeks to perimenopausal or postmenopausal women with hot flashes and (2) if they included a placebo or comparative treatment arm. Topical preparations, botanical combinations, and dietary interventions, such as soy food or protein, were not included. No language restrictions were imposed on the search. A total of 19 studies met the inclusion criteria. The majority of studies indicate that extract of black cohosh (Actaea racemosa L.) improves menopause-related symptoms; however, methodologic shortcomings in the trials were identified. To date, 4 case reports of possible hepatotoxicity have been published, although previous safety reviews suggest that black cohosh is well tolerated and that adverse events are rare when it is used appropriately. The results of 6 clinical studies on soy (Glycine max L.) isoflavone extracts are mixed. Moreover, the composition and dose of soy supplements varies widely across studies, making comparisons and definitive conclusions difficult. One study challenged the long-term safety of high-dose soy isoflavone extract (150 mg/day for 5 years) on the uterine endometrium. Clinical data from 5 controlled trials assessing the efficacy of semipurified isoflavone red clover (Trifolium pratense L.) leaf extracts to reduce hot flash frequency and severity or to relieve symptoms associated with the domains of the Greene Menopausal Symptom Scale are contradictory. The largest study showed no benefit for reducing symptoms associated with menopause for 2 different red clover isoflavone products compared with placebo. No significant adverse events have been reported in the literature. Single clinical trials do not support the use of dong quai (Angelica sinensis L.), ginseng (Panax ginseng C.A. Mey), or evening primrose seed oil (Oenothera biennis L.) for improving menopausal symptoms. We conclude that black cohosh extracts appear to ease menopausal symptoms; ongoing studies funded by the National Institutes of Health (NIH) will provide more definitive safety and efficacy data. Soy isoflavone extracts appear to have minimal to no effect, although definitive conclusions are difficult given the wide variation in product composition and dose. Long-term safety of higher dosage (150 mg/day) soy isoflavone extracts is uncertain. Semipurified isoflavone red clover leaf extracts have minimal to no effect in reducing menopausal symptoms. Dong quai, ginseng extract, and evening primrose seed oil appear to be ineffective in ameliorating menopausal symptoms at the dosages and in the preparations used in these studies.