| Lignans are one the three main groups of plant compounds classified as phytoestrogens. A study by Medicus Research, on the effects of 7-hydroxymatairesinol (7-HMR) (as HMRlignan™, from Linnea) revealed the naturally occurring plant lignan from the Norway spruce (Picea abies) possesses the ability to cut down hot flashes by 53 percent in postmenopausal women.24 The eight-week controlled study of 20 menopausal women compared two doses of 7-HMR (25 mg/d and 50 mg/d). At baseline, both groups had a similar mean number hot flashes per day; by week four, the 25-mg group’s mean number of hot flashes was not significant but the 50-mg group’s was reduced to 2.7 per day. By week eight, the 25-mg group experienced a reduction of 3.7 hot flashes per day and the 50 mg group experienced 2.0 reductions. The root Kwao Krua or Pueraria mirifica (PM), from areas in Northeastern Thailand and Myanmar, contains a number of isoflavones, such as estrogenic phenol miroestrol. It has been shown to have some benefit for menopausal symptoms. A randomized, double blind study investigated 71 postmenopausal women who randomly received 20, 30 or 50 mg/d of PM or placebo for 24 weeks.25 Mean vaginal dryness in the PM group decreased after 12 weeks of treatment, and the vaginal maturation index increased from 46:43:11 to 11:65:24 after 24 weeks. Researchers from the Hat Yai Regional Hospital, Songkhla, Thailand, found PM relatively alleviated climacteric symptoms such as hot flushes and night sweats in perimenopausal women; however optimal doses need to be clinically assessed.26 The same researchers compared PM to conjugated equine estrogen (CEE), and found the root possesses a similar estrogenic effect as CEE and can alleviate menopause-related changes.27 In another study, they looked at the efficacy and safety of PM and found it to be relatively safe for the alleviation of climacteric symptoms; however, data is insufficient to draw definite conclusions on its estrogenic effect.28 One of the most accepted herbal supplements for menopause is black cohosh, a member of the buttercup family native to the rich woods of North America and grown commercially in Europe. It has been found to possess an estrogen-like action, binding to estrogen receptors and suppressing the luteinizing hormone. In Germany, black cohosh preparations are commonly used to improve symptoms such as hot flashes, depression and sleep disturbance and is covered by a positive monograph of the German Commission E, which allows such products to be labeled for “premenstrual discomfort, dysmenorrhea or climacteric (menopausal) neurovegetative ailments.” Its acceptance was fueled when German researchers found black cohosh produced an effect on serum concentrations of pituitary hormone levels, including a significant and selective reduction of luteinizing hormone.29 Hot flashes have been linked to a significant spike in the release of luteinizing hormone. Another German study failed to identify a single chemical component of black cohosh (as Remifemin®, from Enzymatic Therapy) responsible for the luteinizing hormone suppressing activity, suggesting synergistic effects from several chemical fractions were involved in the biological activity.30 Another German study propelled black cohosh into the spotlight after researchers found 80 percent of the 629 women who underwent six to eight weeks of treatment with black cohosh had improvements in hot flashes, fatigue, irritability and vaginal dryness.31 At eight weeks, 50 percent of women were symptom-free. More recent studies on the herb have also indicated benefits. A 12-week double blind, placebo-controlled trial of 304 women with menopausal symptoms found black cohosh was more effective than placebo.32 The researchers noted black cohosh’s effect size was 0.03 to 0.05 Menopause Rating Scale units, which is similar to recent HRT study results and can be considered clinically relevant. A three-month study of 120 menopausal women comparing black cohosh to fluoxetine (as Prozac, from Eli Lilly) found black cohosh (Klimadynon®, from Bionorica; Menofem®, from AG Natural Health) reduced the incidence of hot flashes more effectively than fluoxetine; however, the drug was more effective than the herb for menopause-related mood changes.33 Another study found black cohosh reduced overall menopausal symptoms to the same extent as a drug and might reduce vaginal thinning, does not affect the cells in an estrogen-like manner, and may protect the bones.34 A substantial study of 244 participants compared black cohosh against the synthetic hormone tibolone and found them equally effective in treating menopause symptoms.35 Systematic reviews have also shed light on the herb’s effectiveness and safety. A review from the University of Exter, United Kingdom, concluded black cohosh is a safe herbal medicine; however, a slight risk of mild transient adverse events are rare, but may occur if taken for a limited amount of time.36 A review from the University of Naples Federico II, Naples, Italy, investigated black cohosh’s efficacy by looking at data from Medline, Embase, Amed, Phytobase and Cochrane Library.37 Investigation of double blind, randomized clinical trials revealed black cohosh did not consistently demonstrate an effect on menopausal conditions, and efficacy of the herb as a treatment is uncertain and further rigorous trials are warranted. A review out of Poland concluded 32 studies showed contradictory results and adverse symptoms are rare (5.4 percent), mild and reversible.38 |
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