14 January 2009

Meta-review slams herbal remedies for menopausal women

by Kate Melville

Reviewing a variety of herbal treatments taken by women for menopausal symptoms such as hot flushes and night sweats, researchers have identified a pervasive lack of clinical evidence to support the use of such remedies.

The report, appearing in the Drug and Therapeutics Bulletin, notes that up to 70 percent of women in industrialized countries will experience vasomotor symptoms around menopause, such as hot flushes and night sweats, prompted by the sharp fall in estrogen levels. On average, such symptoms last for around four years, but in 10 percent of women, they can last more than 12 years.

The herbal remedies commonly used to relieve menopausal symptoms include black cohosh, red clover, Dong quai, evening primrose oil, wild yam extract, chaste tree, hops, sage leaf, and ginseng. But, says the report, little good quality evidence on the effectiveness of herbal medicines, or how they might react with prescription medicines, is available.

Of equal concern is the safety of such preparations, which the study contends is under-researched. Herbal remedies are often assumed to be "safe" just on the grounds that they are "natural," note the researchers. Additionally, published studies, when conducted, were often poorly designed, included too few participants, or didn't last long enough to be of real value. Furthermore, the chemical make-up of various preparations of the same herb may differ, which can make it difficult to compare trial results.

Examples included in the new study are black cohosh, for which the researchers say the clinical trial data is "equivocal," with no clear indication of effectiveness and continuing concerns regarding liver toxicity. Additionally, there was "no convincing evidence" that red clover extract was effective, and little evidence one way or another for dong quai, evening primrose oil, wild yam, chaste tree, hops, or sage.

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Source: British Medical Journal